I have used my subwoofers in "stereo" for years. Read the following and see if you think you might get some benefit from this setup. To do it, all you need is two powered subwoofers with internal line level crossovers, and two extra interconnects.

While it is true that low bass is in theory non directional, the way that bass mixes in the room is not. An example - suppose that you have a group of performers on a stage and they are being recorded by two or three omni directional microphones in front about 15 feet away, which is a common technique. Now say you have someone playing a bass drum or string bass on the extreme left of the stage. The sound of that instrument will reach the left microphone earlier than the right microphone. Considering the frequency of the instruments will be be around 30 Hz in the case of the bass drum and 40 Hz in the case of the bass, the delay in the sound reaching the left and right microphones will be as much as half a wavelength. If you were to play this with a single subwoofer, or two subs with the bass between the channels summed by the crossover as it is when you use the "sub/LFE" output on your pre/pro, this acoustic delay would simply cause peaks and dips in the response of the bass from that instrument. However, if you use stereo subs and are hearing ture stereo bass, this delay between the sound reaching the left and right microphones is heard as natural acoustic mixing of the bass frequencies from those instruments in the listening room, just as it did in the original recording venue. The way the bass mixes in the room is natural, acoustic, and dynamic over time.

As an example of another real-world benefit of stereo subs located next to the main left and right speakers, consider the following example. You have your single subwoofer connected to the "subwoofer/LFE output of your pre/pro, and the sub is located next to your couch, and you have it crossed over at 80Hz (in other words, a pretty conventional arrangement). The distance from your listening position to the mains is 10 feet (the sub is 10 feet from your mains). You play a studio recording that has a bass player coming from the right speaker. He plays an open "E" string. Guess what? The fundamental frequency of that string (about 40Hz) will come from the subwoofer next to you. The second harmonic at around 80Hz will come from both your sub and your main speakers. The 3rd harmonic (and above) of the bass will come exclusively from your mains. As you can imagine, this plays absolute havoc with the harmonic presentation and structure and of the instrument! The effect is of the same type, if not to the same degree, of taking the tweeter out of your speaker cabinets and relocating them a couple feet away. Fundamental frequencies coming from one place, and the harmonics coming from another. The closer the notes being played are to the bass crossover frequency, the worse this disembodiment of the fundamental from it's harmonics will be, as the phase difference between the two will be greater due to the higher frequency. Adjusting the "phase" control of your subwoofer will not correct this: it only corrects for one specific frequency, that of the crossover, and musicians hate being restricted to playing only one note (at least good ones!).

Electronics designers take great pains to ensure that all the frequencies in an amplifer (especially at the low end) are amplified with a minimum of phase shift (this is the reason for DC coupling) - Why mess this up if you don't have to?

I notice an increase in sense of "air" and "realism" on almost all recordings that have live performers, even studio recordings. While low bass cannot be heard as "directional" in the traditional sense, the way the bass interacts as it mixes acoustically in the listening room certainly can be sensed and felt as added realism, and the filling in of that dimension that you are in the space where the recording was made. In addition, sound effects that were recorded in stereo for movies will have their bass reproduced in stereo. This is especially apparent in city street scenes when a bus or train passes. It just sounds more "real" as a result of the way the bass mixes in the room, just like it would if you were there. This benefit wil also be apparent when playing multi-channel discs like SACD and DVD-A, as the main left and right channels will give this added realism from the natural acoustic mixing of the low bass.

This setup is completely transparent to HT, multi-channel, and stereo playback, as anything you throw at it will have the bass reproduced correctly, regardless of format. No more fooling around with the logisitics of what to do with the subwoofer when playing SACD/DVD-A - the bass just reproduces seamlessly.
And best of all, if you have the two subs and extra interconnects, doing this costs nothing.

The ".1" channel is a convention that came from the movie industry, and had no precedent in the music recording industry. It works for movies since in a large theater, very few people are in the "sweet spot", so a mono LFE track is a reasonable compromise.

The ".1" track is a bad fit for music however. Forcing the "movie" model for speaker configuration on a system playing music where a significant number of people are in the "sweet spot" does not work well - it's a kludge in my opinion.

You're basically thinking of your main speakers/subs as _very_ extended full range speakers that can take the demands of film/HT, while at the same time being optimal for music. The LFE track in movies is simply being routed as a mono signal to both of your mains, where it ends up in both of your subs, just the same way it would be if your subs were connected conventionally to your pre/pro with a "Y" adapter. When playing music (either stereo or multi-channel SACD/DVD-A), the entire music spectrum, including the bass, is in stereo, and coming from where it should be: next to (or part of) your mains. One of the results is a cleaner, more coherent and focused soundstage. I've also noticed a heightened sense of realism, and of feeling I'm in the recording venue. Even hearing the low frequency content of the air conditioning rumble and "room tone" that exists in all large spaces in stereo rather than mono enhances the sense of realism. A side benefit is that in movies, you will hear the extremely low frequency content of stereo sound effects (like street scenes with busses and trains etc) that reside in the main left and right speakers in stereo - something that you won't hear in a movie theater, or even on a movie dubbing stage since the mains in these venues only respond down to around 40Hz.


If you have to use a single subwoofer for whatever reasons, at least take into consideration the above and place the sub as close to the mains as possible, preferrably equal-distant from both. This is still a compromise however, since a single sub is still a significant distance from the mains.

While it is true that as the frequency of sound goes down, the ability to locate the source diminishes, but there are a lot of other things to take into consideration. It's just not as simple as "bass is omni-directional so it doesn't matter where you put the sub"!


To configure your system to take advantage of stereo bass, do the following:

First of all, move one subwoofer as close as possible to your main front left speaker. Move the other subwoofer as close as possible to your main front right speaker.

In the 950’s speaker setup menu, set your main left and right front speakers to "Large". Set the subwoofer to "Off". Set your center and surrounds to "small" or "large" depending on their size. Most setups use the "small" speaker setting.

Disconnect the subwoofers from the LFE/Subwoofer output of the 950. Run an interconnect from the main left and right outputs of the 950 to the "line input" of each subwoofer – the left out of the 950 to the left subwoofer, and the right output to the right subwoofer. Run an interconnect from the "line output" of your left subwoofer to the input of your left channel power amplifier. Run the right subwoofer’s "line output" to the input of your right channel power amplifier.

Set the crossover frequency of both of your subwoofers to the crossover frequency you used previously in your 950. You will probably need to re-adjust the level controls of your subwoofers.


[This message has been edited by soundhound (edited April 01, 2003).]

Soundhound, I would love to try this one, have been pondering your posts on stereo subs from the past and my logic tells me the quest achieving what I like in music could benefit greatly from this setup.

But space!. You guys would die if you saw my house. (Picture cottage…and I don’t refer to style).
Right now the Def tech is shoehorned behind the display into the triangle nook it creates, equadistance from the mains.

Something like Gonks SVS (I could literately fit inside of), would not fly in this sq.footage challenged location.
Starting (and stopped) a search on REL subs, without checking out their dimensions.
I feel you might have an inkling of how my personal tastes run in sound, do you think I would benefit from finding one very nice very musical sub Vs the tradeoff of having to find units [very very} small, assuming a degraded performance after factoring cabinet size restrictions, - in stereo? I have a feeling you will pick the stereo setup, but wonder. Any recommendation for quality built mini-me subs?


[This message has been edited by Smart Little Lena (edited April 01, 2003).]

Lena:

If you don't have the space, then obviously stereo subs are not an option for you. BUT - do you really need to park your cars in that big garage - ever built a custom room? I think you "need" a larger HT room! (just don't sneak up on your husband while he's cutting the wood for it!)

Lena,

In addition to the garage, you can use the kitchen space towarts the HT room. Eating out in restaurants is a very enjoyable and fun thing to do. Plus you can sell the Wedgewood, Waterford, silverware and kitchen appliances, using the money towards the HT room and equipment.

Do you really need an indoor bathroom? An outhouse, on the other hand, ...

Paul

p.s. I have two Stryke brand AV15 subwoofer drivers and a Crown K1 amp awaiting. As soon as I get boxes made for each of the AV15s, I'll be doing the stereo sub route.

[This message has been edited by Paul J. Stiles (edited April 01, 2003).]

just don't sneak up on your husband while he's cutting the wood for it!

awohoow low blow!

An outhouse, on the other hand !!! some of you guys have WAF, I on the other hand fight, ACDD
(acoustically challenged diminutive dimensions).

I actually started drawing up a whole new house last summer in a moment of wishful mulling…it seemed to start and stop around the AV area which was about as far as I got with my theoretical floorplan, (I lost interest when I had to draw the outhouses) (I think I have issues).

Regarding stereo subwoofers, Dr. Griesinger of Lexicon observed the psychoacoustic phenomenon where bass coming from directly in front of you is perceived as being inside your head instead of in front of it. To this end, he came up with something for the Lexicon processors called Bass Enhance, which takes the bass from the center channel and redirects it to side subs or full-range mains, plays a few games with the phasing, and in principle offers a significant advantage over bass without this technique.

In practice, this technique has been shown to be highly room- and position-dependent. It's an option on the processors, so some people (like myself) use it, and others do not.

Jeff

Folks,

I've used multiple subs for years - not for "stereo" reasons but rather because I've found it much easier to balance the sound (bass) throughout the listening area when using more than one sub.

In my main theatre's current set-up I've recently gone to using three subs (Velodyne Servo 1200, B&W ASW1000, and a passive home-built from my engineering design days that uses extra-high density particle board, four 6 1/2" Polk drivers, and a 12" Polk passive radiator) in what is a relatively small room. It's producing the best (admitedly a subjective term) sound that my set-up has ever produced. On top of that my mains are large towers with a tested -3db point of 27Hz - so they're not lacking much in the way of "musical" bass either.

On the subject of stereo subs, I'm sure that some people can, or at least think they can, hear a difference. In my case, using only two subs, located close to their respective left and right front speakers, I hear no difference at all - and neither do a number of fellow listeners who have done some "blind" listening tests with me. I currently use an ICBM-1 which, as you know, has a switch that allows mono or stereo sub operation, so I can switch between the two modes instantaneously. Nobody hears a difference. Nobody can tell which is mono or which is stereo. Even though I'm using two different subs, and even though there is no way that I would ever be able to match the subs up exactly in terms of output level (I use a Radio Shack analogue level meter), cross-over point (I rely on the indicated settings which are probably off by at least 10-20%), or low frequency extension (since the Velodyne goes much lower that the B&W). So despite even these differences, there is no detectable difference - at least not to my ears. I can only imagine that identical subs, set up identically, would yield even less of a difference.

Just my opinion / observation. Not that I am doubting anyone who does notice a difference. That's the beauty of this obsession (er hobby) called home stereo / theatre.

Jeff

The benefit of having stereo subwoofers is greatly recording dependent. The recording method that takes the greatest advantage of capturing bass in stereo is "spaced omnidirectional". This microphone technique captures both intensity and time information. Co-incident and near co-incident techniques such as X-Y, crossed figure 8s, ORTF etc, capture only intensity differences, and thus are less likely to display enough information to make stereo bass audible. Studio recordings can go either way, depending on the particular microphone techniques employed, how many musicians are playing together in the same room, and panning.

On recordings I make, I use three spaced omnidirectional microphones in much the same manner that the classic Mercury recordings were made, and which Telarc mostly uses. The effects of stereo bass are most apparent when recording in large spaces with long low frequency decay times. Several recordings of pipe organs I've made in large churches display a beautiful sense of space from the directionality of the low frequency ambience.

Soundhound,

I should introduce you to Dr. Griesinger at some point. I suspect you'd both benefit very much from a technical conversation.

Jeff

Soundhound I applaud you and I absolutely agree with everything you said although I could not have explained or given the details as well. Stereo subs set up correctly in my system was the single best improvment in sound quality that I have made. (with the exeption of the speaker purchase) I do exactly as you said and have the subs directly beside the mains. I do have the LFE connected along with the main L/R channels but the controller for the subs allows me to defeat the LFE input and just use the mains signal. Your organ bass comment is right on because on of my favorite DVD-A's is Deep Purple and that Hammond sounds better with the stereo setup. No doubt in my mind.
SH I do have a question though. Do you think that maybe certain setups wouldn't benefit if the main L/R speakers are to close together? It seems a lot of people tuck the speakers as close to the monitor as possible which isn't how I have mine set.

I don't think there would be any problem with the stereo subwoofers, but I wouldn't want to put speakers that close together in the first place. Having speakers close to big reflective objects can also play havoc with imaging.

it should be noted that the stereo sub setup will produce best results with acoustic recordings only, as there is almost never a microphone involved in electric bass (or any electronic instrument) recording. DI is used, and that signal is normally 'placed' equally in the l&r mains (not accounting for the 6th, or point one channel in sacd/dvd-a).

lexicon's dr. 'G' (with bass enhance) is taking a page from bob carver's holograph generator and requires PRECISE placement of both speakers and listener's ears. these 2 points are, no doubt, why bass enhance is said to be room and source dependent.

lexicon is the only pre-pro available with stereo sub outputs AND A SEPARATE LFE output.
my guess is that this configuration allows for the bass enhance feature, and is the only reason for it. otherwise, lexicon would be touting the many benefits of this configuration. the simple fact that bass enhance won't work if the LFE signal is summed with the redirected bass signal tells you that soundhound's setup won't either when there is LFE content.

80 hz is too high for a subwoofer.
1 subwoofer to reintegrate redirected bass into the soundfield is enough when the LP point is around 40-60hz.
the second subwoofer is needed for a discrete LFE signal, as the summing of LFE with redirected bass is where almost all bad things happen (intermod distortion, too much demand placed on a single sub system, crossover holes/humps, loss of any chance at stereo bass, phase problems, etc).
stereo subs, placed as soundhound suggests is a plus, but only for acoustic, 2 channel recordings and only if LFE ain't summed into them. also, the fact that 40hz is a wave that's 28 feet long, and therefore is reflecting off many surfaces before it ever gets out of the speaker, matters (this is, in fact, why bass is omnidirectional). soundhound has matched, ear level, direct radiating subs, so he hears the note first and the reflected notes afterward. most HT subs are downfiring or direct radiating, but sitting low to the floor and in the corner to use the corner for gain, which greatly lessens the stereo effect, especially at 40 hz.

dr. 'G' spent too much time developing bass enhance and overlooked the fact that the key to correct multi-channel audio bass is a DISCRETE LFE SYSTEM. among many other benefits of a discrete LFE system, it allows for a full range .1 channel by simply high passing a satellite speaker off the LFE sub (in dvd-a/sacd).

bottom line...i agree with soundhound, as far as placement of the subwoofers. i know the end result is real, and not perceived or imagined. when i record bass tracks in the studio, i have to play alone, while a monitor plays the song because headphones cause the music to arrive instantly to my ears and that tiny discrepancy in time arrival throws my timing off completely (as i am used to live performance much more so than studio work. i agree with lexicon as far as a discrete LFE output. i agree with stereo subs, but don't think they are the important part of the setup, unless 2-channel acoustic recording playback is your primary interest, and you have the room to properly place 3 subwoofers.

of the 3 things, discrete lfe output (and subsequently, crossover, phase and delay processing of same) is the most important, because, only then can you properly set up any sort of subwoofer system for redirected bass.

I fail to see how routing the LFE into the stereo subs where it is reproduced by both, will not work. The LFE in the case of films is synthesized in almost all instances anyway - I know, I create some of them! Please educate me on why sending this signal to two subs equally "will not work"

I said from the beginning that this was best for acoustic recordings, and recordings in large venues especially. Last time I checked, this applied to a significant number of recordings out there. I know it does not apply necessarily to some studio recordings. If you listen to jazz and classical music at all in stereo, this is where the benefit is.

I'm amused by some of the resistance I've encountered on this subject on this forum, and on another I've posted this on. Maybe I'm just too dense and don't get it - maybe the marketing machine has convinced too many people that the LFE is sacred and must be reproduced only by a dedicated subwoofer. I've simply tried to describe a simple and cost effective way to make a HT system that is also used for music listening as effective as possible in both formats.

There are a very significant number of people who do listen to two channel (stereo) music. To ignore it's existance is turning one's back on a vast library of recordings that will never exist in a multi-channel format. The music is the message, NOT the way it's delivered - 5.1 channels, 2.0 channels, or even 1 channel.

[This message has been edited by soundhound (edited April 05, 2003).]

I'd just like to add a couple of comments to my earlier posting on this topic.

My guess is that anyone who has gone from using a single sub to two or more has noticed a big difference - and hopefully an improvement. The question is whether you hear a difference between two subs in mono, and two subs in stereo. And I would argue that, as with all listening tests, unless you can keep everything else equal, and unless you can transition between the two states in a very short period of time, you might be giving your brain too much time to forget what it has just heard. "Time" is a serious factor when it comes to our ability to make comparisons. (Heck, our sense of hearing varies throughout the day depending on any number of factors - something that I proved to myself by taking a number of audiometry tests throughout a single day and seeing that my sense of hearing did indeed vary slightly from one test to the other.) In my case, by having to do nothing but switch between mono and stereo on my ICBM, I'm getting as close to an instantaneous switch in states as possible - and then only when I have someone standing behind the equipment racks to make the switch while I listen. (It's also important that the listener does not know the initial state (mono or stereo) and that a "switch" between states can be no switch at all, when conducting the tests.)

Since my first posting on this topic, I've given it a bit more thought and wonder if stereo subs might produce a noticeably different sound compared to a two-sub mono set up in the case where the front main speakers have less bass extension. I can't easily swap my large mains for less bass-capable speakers, however I CAN use the ICBM to simulate this by simply changing the crossover point. A series of listening tests with the ICBM on bypass, 40, 60, 80, 100, and 120 HZ should either prove or disprove the hypothesis.

When I can find the time I'll see if I can set something up and will report back on the results.

Regards.

Jeff Mackwood

Instead of trying to "prove" or "disprove" this, why don't you simply try listening to a good recording with this configuration and if you like it, keep it, and if you don't like it, put it back the way it was?

Doesn't seem like a terribly big deal to me, but then I have a simple mind, and that simple mind doesn't see any benefit in going from stereo to mono below a certain frequency if I don't have to!

[This message has been edited by soundhound (edited April 05, 2003).]

[QUOTE]Originally posted by soundhound:
[B]I fail to see how routing the LFE into the stereo subs where it is reproduced by both, will not work. Please educate me on why sending this signal to two subs equally "will not work"
____________________________________________

the LFE sub, for movie reproduction, must be capable of subsonic to 120ish hz PLUS redirected bass from 5 satellites (or, 2.5 satellites, in the case of stereo subs). what happens to the 40hz bass guitar E string note when a 30hz (example) LFE+10 note is blasted on top of it in the same amp/speaker? if it's mixed too loud, how do you compensate? if it's out of phase, how do you adjust it? what happens to the LFE's playback capabilities when the sub's LP is set at 40hz to blend with a 40hz HP selection? what sort of subwoofer/amp is needed to survive the assault, and will that sub/amp be the best one for music? what does it do to the stereo sub effect you tried for in the first place? what happens if the .1 channel is a height channel, or contains vocals (in the case of dvd-a/sacd) or other higher range info?

1. adding 5 channels @ 103db and 1 channel @ 113db (LFE+10db) results in a requirement for 121db for the sub(s). testers who have played the dolby test dvd know that 'practically all' systems have a serious limitation in this area.

2.a sub system with a 1w/1m sensitivity of 89db requires 1600 watts to acheive 121db (vs 260 watts @ 113db).

3. intermod and harmonic distortion are unacceptable.

4. volume levels (between LFE signal and RB signal) are not adjustable when they are both summed into one signal.

5. manufacturer's claims notwithstanding, no sub with this capability is worth a crap for music.

6. the .1 channel is unnecessarily limited by the necessity to select the proper LP point to reintegrate redirected bass into the soundfield from which it was extracted.

of course, it 'works' the way it's done now...just not very well. the best education is to segregate the LFE signal in it's own system and run some tests yourself.
__________________________________________
I said from the beginning that this was best for acoustic recordings, and recordings in large venues especially. Last time I checked, this applied to a significant number of recordings out there. I know it does not apply necessarily to some studio recordings. If you listen to jazz and classical music at all in stereo, this is where the benefit is.
____________________________________________

i offer no resistance to the above statement, and apologize if i gave that impression.
__________________________________________

I've simply tried to describe a simple and cost effective way to make a HT system that is also used for music listening as effective as possible in both formats.
___________________________________________

the post is appreciated...in fact, i LOVE this thread. as i said, for 2 channel, acoustic reproduction, i believe your suggestion is a very good one.
____________________________________________
There are a very significant number of people who do listen to two channel (stereo) music. To ignore it's existance is turning one's back on a vast library of recordings that will never exist in a multi-channel format.
____________________________________________

agreed.
___________________________________________

The music is the message, NOT the way it's delivered - 5.1 channels, 2.0 channels, or even 1 channel.
___________________________________________

this is where i disagree. the message of music that's written for and properly mixed in 5.1 cannot be delivered in another format or with bass that never arrives at all, arrives distorted or destroys your system. it's like painting a masterpiece, only to be asked to deliver it to be viewed in watercolor.

the answer is a simple one. 2 discrete outputs, 1 LFE, 1 RB (or, 2 RB, if you prefer stereo RB) and a switch that sums the LFE and RB into the RB jack for those who prefer the current system. not a lot to ask.

Bosso:

Your points are well taken, but I think you way overestimate what is being demanded of the subwoofer by the LFE channel. Also, the listening levels you are talking about will not be used in any home enviornment, at least by anybody who wants to keep their hearing intact. I don't even listen at those levels!

I think you are also blowing up the issue of potential phase problems too. They just don't exist in the real world, on real world movie soundtracks.. Movie LFE tracks and the bass in the other tracks just isn't that radical - mostly it consists either of slowed down natural sounds, of filtered pink noise that has had an envelope overlaid, or sounds processed by a DBX bass synthesizer. There are no "phase" problems to be had; they would immediately make themselves known during the film's mixing process. It is routine during the mixing process to do "crashdowns" into stereo or even mono in order to catch any potential problems down the road.

The film's mixing engineers take into account the fact that the film will be played under much different circumstances, and on lower quality system than on the dubbing stage. They mix the bass accordingly, and they have phase meters where they monitor for potential problems.

There just isn't as much to worry about as you seem to think there is.

[This message has been edited by soundhound (edited April 05, 2003).]

my system consists of a separate preamp, crossover (LP/HP, for full range use of the .1 channel), slope selection, delay and 360 degree phase control, (designed in consultation with and built by phil marchand) a pro sound amp and 1-18", 10 cu. ft. speaker for LFE only, which is taken directly from the player.

the 950, through the SW output sends only redirected bass to another pro amp and 18" sub. the 950 handles the LP for redirected bass.

when i play LOTR for whomever is there, (i don't have the LFE bug, because i get LFE from the player) they always are very impressed with the insane bass levels.

i, however, cringe as i watch the clip indicators (both the preamp's and amp's) as they flash red. i don't know what the engineers took into account, but this disc has everything the format can muster.

now, imagine it's summed with the bass from 5 channels into the average plate-amp-powered 12" sub, without the built-in limiters those products use. it would not survive.

and, what happens to the music that's playing while the LFE plays? i can switch from discrete, 2 subs, to summed, 1 sub...on-the-fly. the difference is dramatic.

it's even more dramatic a difference when playing sacd multi-channel. i can use different LP points, slopes and volume to dial each disc's LFE content without effecting the redirected bass, which belongs to the 5 channels it was derived from and requires different LP point/slope/volume. you only need to hear the difference and draw your own conclusions. like you say above...just try it. you hear a difference and like it, keep it. if not, switch back.

my phase concerns don't center on the source, but the processing and playback of it. a subject that i'll address when it's not so late.

soundhound...thanx for everything.

Bosso:

From your description of LOTR on your system, I can only imagine that you have your LFE cranked far beyond what was intended. I played this film in my room several weeks ago (in DTS) and while the bass was up front and constant, it was not out of the oridinary or "extreme" by any means. I know the calibration of my room since I have to transfer projects from here to dubbing stages with no surprises in levels, bass or otherwise. I normally play back films with a 6db boost on the subs over what the film was mixed at - I like bass as much as the next guy. When I mix, I return them to flat.

If you were to visit an actual dubbing stage where films like this are mixed and listen to the frequency balances, I am quite sure you would shocked at how "mild" the LFE bass really is in the mix of the same films you listen to at home. The engineers will never sacrifice the intelligibility of the dialog in order to get more "boom" from the soundtrack. There is only 20db of headroom above the nominal 85db level of dialogue to work with before the master recorders reach clipping. Loading them down with too much low bass leaves no room for more important things like the music, dialogue and the other sound effects. The purpose of the LFE track is to reproduce this bass so that the main speakers don't have to deal with this power and headroom-robbing signal.

If your clipping lights are flashing constantly, I really think you have the LFE track boosted too high. You might like it like this, and I can understand that, but you also are probably not hearing the film's bass as it was intended.


[This message has been edited by soundhound (edited April 06, 2003).]

An EXCELLENT thread, gentlemen, congratulations.

(Soundhound, practicing your typing?)

what can i say? the system is calibrated properly.

i have dts-es discs, pearl harbor, gladiator and LOTR.

gladiator has very little LFE, actually. LOTR has enormous LFE content. i have to back off quite a bit with certain scenes to equal gladiator or pearl harbor (or, are you saying it's the player or the preamp or the amp?).

the clip indicators don't flash constantly, only during the scenes i use for demo purpose, and i assure you, i don't have the levels set too high. after many hours with many discs and all formats and nearly every conceivable routing/processing scheme...i know a hot signal when i see one.

my point is, really, that i don't believe that average systems handle LFE+RB well at all. they have subsonic filters, peak limiters, grossly distort (and most people simply don't recognize LF distortion), boost certain freqs with cheap eq, produce phase anomolies (the 950 can send RB from 5 different speaker locations at 3 different crossover points plus the LFE at a fixed 120 hz to a single sub that's usually 'placed' where it fits in the room best, close to an a/c outlet), holes or humps in response at crossover and do not play back the original content very well at all.

as far as what engineers would or would not ever do, mixes of all surround formats differ so wildly from one disc to the next, that i simply don't buy that statement. in fact, the fate of hi-res multi-channel audio rests largely in the engineer's and producer's hands. so far, not so good.

using a sub to augment an inadequate stereo setup is one thing. multi-channel audio is vastly different, mostly misunderstood and very far from a 'set-it-and-leave-it' standard. i feel about stereo like i felt about mono when stereo came on the scene. it frustrates me to hear the 'everything is perfectly fine the way it is' response. i guess if i was selling a bunch of this or that dolby or thx or whatever gadget, i would say the same thing.

separating the LFE to it's own system, helps the situation in more ways than one, and not just a little. of this fact, i remain convinced.

I was specifically referring to film mixing engineers here! I know them, I work with them, and I know the consistency of the mixes that come from the stages in Hollywood. In the film industry, everybody needs to be on the same page and in sync with each other, otherwise money gets wasted, and the career of an engineer who's mixes don't hold up in the real world of theaters would not have a job very long. The mixing engineers on the various top stages work pretty much exclusively on their "home" stage. They have teams that they always work with, and they know what to expect. It simply can't be otherwise when release dates are looming, sometimes only days from when the film is finishing it's mix. Films from the various studios that are mixed in the same general era (the 1970s, 1980s, the 1990s etc) sound remarkably alike in their balances. If you are getting "wildly differing" sound from films from the same era, something is wrong in your system.

Multi-channel audio discs are something else. The music recording industry is by comparison extremely unstructured in it's practices when compared to the "factory" like workflow in the film industry. There are no particular requirements or qualifications necessary for music recording engineers, and they don't have to answer to anybody in particular if their mixes don't hold up on real-world systems. There is no "standard" formatting for the use of the various channels: the use (or non-use) and purpose of the LFE channel is still a matter of individual intrepretation, depending on who is doing the mixing. Also, the whole multi-channel music industry is very young compared to the film industry (which has had around 80 years to evolve) , and there is a learning curve.

[This message has been edited by soundhound (edited April 06, 2003).]

This has been a most informative and entertaiing thread. Bravo!

I just set my system up for music and let the movie soundtrack performance land where it lands.

Little pieces of black electrical tape over the clipping indicators will fix that problem.

Paul

------------------
the 1derful1

Considering the huge sonic penalty that the movie soundtracks suffer when encoded into Dolby Digital or DTS, you are being very, very wise!

it's been said here many times...no complaint, no fix.

i'm no fan of dolby labs, and i regularly communicate that fact to them. i leave dts alone, because they represent the ONLY competition to an otherwise absolute monopoly.

when i get some time, i'd like to list a few titles and get your opinions, SH. if it's a bother, i certainly understand, just let me know.

i tried facing the equipment to the wall, shutting off the lights and closing my eyes. it's worse that way.

Music vs Movie Soundtrack

SH, your insight on the production of the movie soundtrack is enlightening because I was with Bosso on this. I also thought that music bass and sound effect bass would interfere with each other. The soundtracks and the systems most of us run are made for each other and I'm glad someone else is responsible for making sure sound effects, music and dialog are perfect in the mix. Bosso, have you tried LOTR DD release along with the DTS release? There appears to be a big difference between the two and the DTS is actually quieter wrt LFE. There must have been some tweaking between theatrical release and the subsequent DVD releases.

It'll be a long while before multichannel music mixing and production settle down. Until then, there'll always be a tweak we need to perform before settling down with a nice DVD-A or SACD.

To be a little more on topic; I find it interesting that you both use 18 inch subs. Have either of you tried 15s or direct radiating 2-10s? I ask because 18s need an awful lot of help from other speakers to be musical. Sure, they are rock solid on the fundamentals but they are lacking on the harmonics that give the low E on a bass and the thump of a bass drum their character. I wonder if stereo or dual mono 18s can truly have the effect you guys describe on properly recorded music or is it the speakers that are handling the low midrange and higher. I would think that to get the stereo/delay effect in the bass from the original recording, you'd need a large enough room.

I have a pair of 18s that I use for my band's PA but I wouldn't use them for my bass guitar. Maybe I'll try to get my family out of the house for awhile and set up the 18s and my 210s. Now where did I put that hand truck?

DollarBill:

There is absolutely NO relationship between speaker size and how "musical" or "fast" a speaker can be if the speaker drivers are properly designed, for their size. "Small woofers are faster" is myth that a lot of people accept as gospel because it's been repeated enough by the audiophile press. Large woofers are not inherently "slow" - BASS is "slow"! If the subwoofer (or any speaker) does not have a sufficiently large magnet and voice coil in relation to the weight of the cone, the speaker will respond slowly, and will continue to move when the musical note stops - "hangover". This will sound "muddy, like "slow bass". The motor assembly of a speaker acts as an "engine" and also as a "generator". This generated voltage, called back EMF, is absorbed by the low output impedance of the power amplifier - this controls the cone of the speaker, keeping it from moving or "resonating" on it's own. The larger the motor assembly the speaker has, the more effective it will be in controlling the speaker. If a speaker has a large magnet and voice coil (my subwoofer's voice coil is 4" in diameter), the "motor" can accelerate the cone as fast as desired. Want the cone to respond faster? Build in a larger motor assembly. Simple as that, just like the engine in a car. If you're trying to make an Abrams tank accelerate faster, you don't put a Honda Civic engine in it.

It costs a lot of money to build a speaker with a massive motor assembly, and frankly, most low and moderate priced subwoofers are lacking in this regard. As you go up in the price range, you are buying a subwoofer that's capable of more articulate reproduction. These can be 8" all the way up to 18" and beyond.

There is NO advantage in going to a smaller woofer, "musical" or otherwise. There are huge disadvantages however, low frequency extension and efficiency being the main ones.

It may shock you to know that the "woofer" in my system that operates from 60Hz up to 1,200Hz is 15" in diameter. However it is more than able to "keep up" with the frequency range it reproduces because it has an extremely light cone, and a massive magnet structure and voice coil in relation to the weight of the cone. The voice coil gap is very focused on the voice coil, and the driver is very efficient as a result. The woofer is also horn loaded so the woofer has to move only a slight distance in order to create very high sound pressure levels.

If I thought that I could improve on my bass by purchasing smaller subwoofers, believe me, I would do it.


[This message has been edited by soundhound (edited April 07, 2003).]

I don't disagree with you at all. I thought you had 18 inch woofers. Also, I guess I really didn't make my point above. My point is that a large woofer will (should?) have more trouble reproducing the higher frequencies. 18s, taken by themselves, will not produce the higher octaves as well as 15s or 10s and it's these higher frequencies that define the timbre of a bass guitar or a bass drum. I think it's also the area in which the sound becomes directional and the stereo effect begins. My guess is that your midrange drivers crossover nicely with your subs. When listening for the bass separation imbedded in the recordings you're discussing, are you sure it's the fundamentals you're hearing or the first few overtones (harmonics)?

A good bass driver needs to be stiff and have large excursion ability. This is at the sacrifice the midrange capability of the driver. Combine this driver with a properly tuned cabinet and you can get good low extention. The size of the driver is less important. I think you can go with smaller drivers, or a combination of them in the case of a 2-10, and still get good low frequency extension and efficiency. The 2-10 I use for bass guitar has better low frequency extention than the 15 inch cab I used to use because of the construction of the driver and the design of the cabinet.

I'm not trying to knock your idea here. In fact, I'm going to try it if I can get rid of my family for a day or two. I can setup two 18 inch bass bins and two 2-10 bass guitar cabs. I don't know what the measured response of the 18s are but my 2-10 cabinets are +/-3 dB at 41Hz and -6 dB at 31 Hz, discounting room coupling.

DB: after reading your post, i decided to read the info (which i never do) that came with this version of LOTR.

i have the 4 disc 'special extended edition' version. it has only DD-EX and DTS-ES versions. inside the booklet, it says:

"...rather than simply inserting deleted scenes, jackson approached this extended edition as if he were creating a whole new version of the film. he and the editor...worked to bring each scene up to the same polish as the rest of the feature-visual effects were completed, dialogue was recorded and sound effects were created. to make sure the scenes flowed, howard shore composed and recorded a new score with the london philharmonic..."

so, now i'm wondering how much this soundtrack is different than the DD/DTS version. i'll rent the disc this weekend and see what's up.

i hate 'the making of' discs. they have really bogus info (i care less how the visual effects were accomplished...actually hurts the film, to me) and they NEVER show the mixing and/or how the sound effects were produced. SH, you should protest.

i guess no one else can comment, as the 950 isn't outputting the LFE of the DTS-ES version.

I'll be interested in reading your comments on the comparison between DD and DTS for LOTR.

Actually, I found the "making of" segment on sound pretty enjoyable on the "Attack of the Clones" disc.

DollarBill:

>>My point is that a large woofer will (should?) have more trouble reproducing the higher frequencies. 18s, taken by themselves, will not produce the higher octaves as well as 15s or 10s <<<

I'm sorry, but are dead wrong in your assumption that an 18" driver is somehow not fast enough to reproduce the higher end of the bass range. As I stated in my original post it is all about the size of the magnet / voice coil assembly in relation to the weight of the cone. The diameter of the cone has nothing to do with it - there can be and are 10" cones that are heavier than some 15" ones. The weight is the only determining factor, period. An 18" driver simply needs a larger motor assembly than a speaker with a smaller cone in order to have equal acceleration abilitiy, and therefore the ability to reproduce the higher end of the bass range as well as the smaller speaker. You are simply perpetuating an audiophile myth if you believe that you have to have a smaller woofer in order to have it respond up to 60Hz. That's just plain wrong. At the frequencies that a subwoofer reproduces, beaming is not a factor. Beaming only comes into play when the diameter of the cone becomes a significant ratio of the wavelength of the audio. The wavelength of 60Hz is over 18 feet. This is a small percentage of the 18" diameter of a woofer.

[This message has been edited by soundhound (edited April 07, 2003).]

Alright, I was more concerned about the large diameter woofer handling the higher frequencies. But since your point is that the diameter of the cone has nothing to do with the frequency response, then why do you think you can't use a smaller driver or drivers in a properly tuned cabinet to get bass as good as that produced from an 18 inch driver?

This is a matter of efficiency and low frequency extension. A larger cone moves more air than a smaller one, and therefore does not need to move as much in order to achieve the same SPL level as a smaller cone. With a larger cone, it is easier to achieve a low free-air resonant frequency, and therefore better low frequency extension. A small cone can have as low a free-air resonance, and reproduce low frequencies, but a 12" cone would have to move much more distance back and forth in order to reach the same SPL at the same frequency as an 18" driver. It would reach it's excursion limits at the lowest frequencies way before the 18" driver for equal SPL. This also means that the 12" driver would be more prone to non-linear behavior because of the distance the cone must travel, and therefore distort more. In addition, any port noise would be higher with the smaller woofer and cabinet.

I use four 18" subs, each in an 8 cubic foot cabinet in order to match the efficiency and output capability of my mains, which have efficiency of 106db/watt. My room also is 6,600 cubic feet. It would be impractical to have enough 12" subs to achieve the SPL and low frequency extension as the 18" subs. With my seup, response extends to 16Hz at 120+db SPL (my 1/2" Bruel & Kjaer instrumentation microphone clips before I can measure higher SPL).

If you don't need high output capability combined with good low frequency extension, a smaller subwoofer will work, however, as output and low frequency extension demands rise, the only practical solution is a large speaker driver, in a large cabinet.


[This message has been edited by soundhound (edited April 07, 2003).]

yeah...but it's way more fun to watch a 12" driver with a 30mm x-max push that amount of air.

i followed you up to the 'practical' part. the wife don't think it's very practical to have "those 2 ugly refrigerators" in the room. and, a good 18" driver ain't cheap.

i've been working on some 12" sealed, eq'd, adjustable Q, 2k watt, 1 cu ft subs. a lot of state of the art technology is required (the driver, small 2kw amp with no heat sink, power supply, battleship tight box, etc.), but it is available these days.

most people use those fast, tight, musical types of words but, the word really is overdamped. thus the adjustable 'Q' circuit. damp it to your liking. this, BTW, is where the discrete LFE comes in. 1 sub slightly underdamped, for effects, and the other, slighly overdamped, for music.

the advantages of the sealed design over the ported are better group delay, less critical box dimensioning, no port to make noise and smaller size. the price is gobs of power, a truly amazing driver and a very cool piece of hardware for mistake-free design of the precision eq.

my 18's have a 6mm x-max, the 12's are 30mm. at very low hz, the 12's are MOVIN'. the 18's movement is hard to notice, by comparison.

i'll miss one thing. the 4 ports are each aimed directly at the listening position. i like to set an unsuspecting friend up with a demo scene that has a sudden explosion type of low freq transient. a second later, the blast of air hits him right in the face. they always duck, as if they are under attack.-->fun<-- and it demonstrates how much air has to be moved to reproduce that kind of tone at that spl.

SH is dead-on correct with everything he said. velo's HGS-18 attests to it. plus...four 18 inch drivers for 60 hz and below....ya gotta love this guy. 120db at 16 hz....and you say MY system is miscalibrated?? 106 db, 1w-1m...gonna take more than 5 watts to equal THAT bass.

actually. LOTR has enormous LFE content. i have to back off quite a bit with certain scenes to equal gladiator or pearl harbor (or, are you saying it's the player or the preamp or the amp?)

Could it be the disc The unworthy asks the LFE experts? Making you wince away from your clip levels. Are you aware that there was a stink about the first LOTR disc released (although your Special E? Is that the 2nd release and I don’t’ know if that was the case with future releases). A reliable source said the disc was layed 10dB hot. And there were various threads around the forums about blown speakers in connection with LOTR.

It is a disc to use with restraint and moderation.

Bosso:

I just have to keep reminding my wife that the subwoofer cabinets are large enough to put her in if she gets out of line

I have modified the cabinets from what they were when I purchased them. They originally had three ports, and were tuned to around 25Hz. Working with the speaker's engineers, I blocked off two of the ports for a new tuning of 12Hz. This overdamped the system: essentially I traded efficiency for low frequency extension. I made up for the loss of efficiency by using 4 subs. They are driven by a 1000 watt MOSFET amp that has something like 16 output devices per channel.

LOTR? my subs aren't even breaking a sweat........


[This message has been edited by soundhound (edited April 07, 2003).]

It seems to me that if you have two woofers that have identical motor assemblies and are otherwise mechanically identical except for the area of their cones and their cones have the same mass (and thus the cone and coil assemblies will have the same mass), it seems to me that the one with the larger area will me more efficient.

Reasoning follows:

I am extrapolating from newtonian mechanics in that the maximum energy is transfered in two colliding bodies (such as billiard balls, for example) when the colliding bodies have the same mass.

In regards to dynamic woofers, the woofer moving system usually (cone and coil) has much more mass than the (nearby located) air it is trying to move. A larger cone is in contact with more air, so all else being equal, the mass of the (nearby located) air is more nearly equal to the mass of the woofer moving system of the woofer and so will transfere more energy from the moving cone to the air, thus the efficiency of the larger coned woofer will be higher.

Also, to reproduce the same SPL, the larger coned woofer will exercise (tax) the drivers mechanical suspension less, and beings many of the suspension compnents have elastomeric mechanical properties, the larger coned woofer will produce less distortion.

In either case, for subwoofer use, the upper limit of the frequencies that the woofer is being asked to reproduced is much, much less than what the woofer can reproduce without significant directionality and is established by the crossover. If this is not the case, then we are not talking subwoofer application or else we are talking about a driver of several feet in diameter.

So, size does matter.

Unless there are space constraints that rule out a big subwoofer (or WAF problems), bigger is better.

Paul

------------------
the 1derful1

now that you mention it, i did hear something about DTS discs being 10 db hot because, when they did their own mastering, they weren't compensating for the LFE + 10db.

as i said, this weekend, i'll rent the disc and see what i find out.

no..my subs don't break a sweat at all either. they can handle 1kw each, continuous. it's definitely the signal from the disc.

bigger is definitely better. unfortunately, most people don't want the subs to dominate the landscape of the home theater (what's wrong with these people??). also, bigger is more do-re-mi.

BTW, i have 3 models of the same sub design (they differ in cosmetics only). one of them has the model # suffix: SLL, after a famous internet poster. as soon as the front panel is finished and attached, i'll post pix for a thumbs up or down.

ok...i couldn't wait for the weekend. just confirmed that my copy of LOTR has exactly 10db hot LFE track. (also confirmed, while i was at it, that my 950 outputs no LFE while in DTS-ES, which is actually a good thing for me.)

Lena...thanx very much for the info!

soundhound: LOTR, disc 2, chapter 9, at ref level + 10db, your sub's amp might sweat just a bit.

model # suffix: SLL, after a famous internet poster Famous or inFamous! I think I feel sorry for it. Would love to see pics when avail.

I need to get busy and order my ES kit. Of COURSE I wrote my serial #'s down. Of COURSE I can't find them. Time to pull out the flashlight. I keep meaning to buy a gooseneck!

Actually, the LOTR disc is a poor example, since it seems that the original soundtrack was just recorded hot. For instance, I generally only listen to the Dolby Digital track when it's available, and on LOTR, the Dolby Digital track is 10dB louder than is typical.

DTS did indeed used to have unnatural loud bass on its discs, but I think this problem has been cleared up.

Ironically, this unnaturally boosted bass was received by listeners as "better" and helped establish DTS's largely-undeserved reputation as a "superior" format.

Jeff

it's interesting how the 950 handles dolby 1 (all speakers 'small'). this is from crystal:

"In cases such as Dolby Configuration 1, a gain (e.g.+10 dB) is not directly applied to the LFE channel to drive the subwoofer. Instead, the inputs to summer 802 are attenuated to acheive the same result. In this example, the L,C,R,Ls, and Rs channels are all attenuated by -15 dB and the LFE channel is attenuated by -5 dB. This implements the LFE +10 dB channel specified for Dolby Configuration 1. However, a compensating 15 dB gain should be applied later, usually in analog, after the DACs."

i'm still thinkin' about this one...

I can't imagine why they would do that!

That would explain why the DD5.1 level is so low on the 950 compared to, for instance, the six-channel bypass. At least it is on my Red Dot system. I understand there is more gain implemented with the final Blue Dot units.

On the other hand, it kind of suggests that the entire issue of surround implementation (not JUST on the 950) is a real can of worms. Remember, this is a description of Crystal's solution and their programming appears in other pre/pros in addition to the 950.

Three short comments, if I may …

First, my compliments to all, especially SH, for contributions to an excellent thread. A fully extended range stereo reproduction can help make the playback of acoustic, large space recordings come just a bit closer to ‘real,’ psycho-acoustics coming into play.

Second, I appreciate this bit of knowledge, assuming I interpreted SH correctly: I don’t have to worry about mixing the LFE with either or both of the R and L stereo, because the LFE will not contain the same audio information, either in or out of phase, as either the L or R … correct?

Thirdly, those that think a perfect subwoofer will be ‘fast’ enough to help make the ‘thump’ of a bass drum (or similar source of complex-frequency, sudden and large-amplitude sound) seem like that drum has moved right into the room with them has a conceptual problem. To make that happen, one would need improved capability across more of the sound spectrum than a subwoofer is intended to reproduce. Imagine the perfect loudspeaker that can produce frequencies from 0.1 Hz to a megahertz, flat, without distortion, at amplitudes so low that it actually absorbs any unwanted sound in the room, to levels so high that one could level a city with it. Now simply do one thing to limit its performance: restrict it to frequencies below 80, 60, or 40 Hz. No matter how much amplitude and ‘speed’ the transducer has, so much of the sound of a bass drum thump will be missing. If one needs more realism in sounds such as a bass drum, improvement in the woofer and mid-range may be equally or more important than improvements in the subwoofer.

That said, IMO, you can’t get close to realism without the range of frequencies that are covered by one or more well placed and adjusted subwoofer(s).

By and large, you are correct. Very occasionally, on music there will be a low-passed "copy" of the lowest octaves of the orchestra routed to the LFE channel, in order to augment the mains. However, this information will always be in polarity with the same information from the mains. If it isn't, somebody screwed up somewhere In no instance will there be bass in the LFE (with music) that is not also in the mains.

You're right about the bass drum example. A sub needs good integration with the mains in order to present the sound event without corruption in it's harmonic structure. This is why one benefit of stereo subs comes from the fact that each main channel has it's associated subwoofer as close as possible to it. A coherent sound front relies on placement of the drivers.

SH,

Let's say you have a pair of subwoofers (I do) and you're expecting the arrival of a dedicated LFE subwoofer (I am). Where would you place the LFE sub, or does it not matter very much?

Space is at a premium in my room. There aren't a lot of choices ...

Jeff

in stereo, of course, there is no LFE, so the following concerns multi-channel audio only:

it's not whether you have to worry about mixing LFE to either FR or FL. the mono LFE channel is automatically mixed into them both equally in this configuration which definitely erases the stereo effect. your only option to avoid this is listed below.

"...because the LFE will not contain the same audio information...as either the L or R..."

this is incorrect. almost ALWAYS, when there is LFE signal, it is the same signal as that sent to the L and R.

phase problems MAY occur, not from the source, but either in the filters used (there are 2 high pass filters on the FL/FR woofers, 1 is passive and 1 is active. there are 2 LP filters used for summed redirected bass/LFE, 1 digital and 1 active and there is a global 120 hz digital LP on the LFE), and/or lobing effect caused by the distances from FL/FR vs from the 2 subs. (distances being measured from the voice coils).

because any speaker set to 'small' will have it's bass summed in a summing block before it's sent to the FL and FR, it's my opinion, in multi-channel modes, the only way to preserve stereo bass through subs is to set all speakers to 'large' and use a 3rd sub for dedicated LFE. this avoids any sort of summing, which degrades the stereo effect and, reduces intermod distortion, which occurs any time 2 inharmonic tones are sent to 1 speaker to be reproduced.

duplicate post....

[This message has been edited by soundhound (edited April 10, 2003).]

I would try to place the dedicated LFE sub as close to the mains as you can, wherever that is. That way, at least any common bass from the mains and the LFE would reinforce each other by way of mutual coupling.

duplicate post...

[This message has been edited by soundhound (edited April 10, 2003).]

Hoo boy, that should prove challenging!

Thanks for the suggestion. I'll try to act on your advice if my room will permit me.

Jeff

I'm considering using stereo subs with the 950/ICBM/755.

Anyone care to recommend a pair of subs that would work well in a 16' x 14' x 9' listening room with large, full-range (down to 30hz) mains? Assume that they would be used 50/50 music/HT and that I'd like to achieve value that's on par with the Outlaws.

Thanks in advance.

Pleary,

I just ordered a sub from my friend Brian at Rutledge Audio Design (http://www.rutledgeaudiodesign.com). He makes a great 19x19x19 cube that extends down to 25 Hz +/- 3db and is -8 dB at 20 Hz. In terms of cost, you can get it for $580 for the 150 watt model or for $20 more, you can get a 250 watt model! An incredible bargain.

Check out his site and tell him Jeff sent you!

Jeff

Check out SVS subs (svsubwoofers.com) , they are an excellent value. I've got one of thier 16-46PCi's in my system, and it blew away the competition. (I was demoing a paradigm PW2200...which I had demoed against every subwoofer at my dealers shop...which included subs from Velodyne, M&K, Paridigm, Paridigm Referance, and Boston.) The PW is an excellent sub...ratteling the walls of my house to the foundation. It was a new sub (man, I do love my local shop), so unfortunatly it was a little "stiff" and a little sloppy in the accuracy department. (Which I do expect would have tightend up a bit after the cone broke in.)

The SVS was a better performer then the Paridigm. The only setback is that the SVS is a very odd duckling. (It looks like a giant black water heater) The 16-46PCi is taller then my monitor 11's. However since I'm a swinging batchelor...I don't have anyone complaining! (Except the neighbors).

Well I am the proud owner of a JBL-PRO Cinema Subwoofer in my room it is flat at 25hz and this subwoofer really shakes my home, I am using an Adcom 555 in bridge mode to power this beast.
--------------------------------------------------------------------------------

4641
Subwoofer 4641 Specification Sheet

Single 460 mm (18 in) High Power Subwoofer.
Approved by Lucasfilm, Ltd. for THX® system installations.





Low Frequency Driver: 2241H
Frequency Range: 25 Hz - 500 Hz (-10 dB)
Power Capacity (Continuous Pink Noise): 600 Watts
Power Capacity (Continuous Program): 1200 Watts
Sensitivity: 98 dB SPL (1W, 1m, 3.3ft.)
Crossover Frequency: 80-150 Hz recommended
Nominal Impedance: 8 Ohms
Dimensions (HxWxD): 1010 x 674 x 450 mm (39 3/4 x 26 1/2 x 17 3/4 in)
Net Weight: 60 kg (131 lb)

That's similar to the 18" JBL woofers I use, which is the 2245H. The difference is the 2245H has a foam surround and has a bit lower resonance and low frequency limit of 20Hz for the driver alone. It gives up 3db of efficiency from the 2241H. They are in the 4645 subwoofer cabinet that I re-tuned for 12Hz. Playing together, they go down to around 16Hz flat.

Thanks Soundhound for the stereo subs idea. My l&r mains each have 12" subs, so I tried it and you know what, I could feel the difference from my listening position. So then I was wondering what to do about the LFE channel for movies and I just so happen to have a 15" dBX passive sub. Hmm, Outlaw 770 driving 7 channels, the 7th channel is really the same as the sixth, so I bridged those two and used the spare for the dBX (rated at 6 ohm) and now, I really have some serious earth rattling bass. Not boomy either, but tight and good extension.

There is a track on the Phantom Menace when they first get to the underwater city, something like the 7th or 8th chapter. Anyway, there is a bass line to this chapter that I never knew was there until I moved to this setup.

FYI, I have the dBX/LFE channel right up front with the other subs, but up under the stairs so the corner becomes a reflector/multiplier for the sub. My room is small to med sized.

I am hooked, I would recommend others give stereo subs a try. Kinda cool when the ship flys by in the movie and you can feel the bass line move with it from one side of the screen to the other. It does enhance the movie experience. And since I have the surrounds remixed for the subs in the LFE channel, I don't miss out by having the extra dBX sub.

i'm lost. can someone help me out and explain what this post means?

You are correct sound these JBL_PRO are the real deal, your room is much bigger then mine so I use only one Subwoofer for the .1 Dolby Digital or DTS.(according to JBL theater requirements you need one 4641 for a room that is 700 M3 to be on the safe side)I think i mention my main speakers the GREAT JBL Studio Monitors 4430 and the 8330 for surrounds.I am just waiting to find a single 4430 for my center channel so that I can use all my front channel speakers at full range.

.

Same surrounds I use. They are the ones that are used in dubbing theaters and cinemas....can't get closer than that. I've had no trouble running them "large", even with some of the abuse I throw at them. They are actually pretty fine speakers in their own right, and if you want to get really anal, you can flip that EQ switch on the input panel to match their response to that in a cinema. I constructed 1/8" thick plates with 4 "keyhole" shaped holes that mate with the four screw holes on the rear of the cabinets. I screwed the plates with 3/8" spacers to the wall, then the speakers hook down into the keyholes easily (I have 4 screws partially screwed into the four holes in the cabinet back). This makes a really clean installation and the speakers sit very close to the wall. They even will stay on the wall during an earthquake - I know that first hand



[This message has been edited by soundhound (edited April 13, 2003).]

alphanstein:

Glad you like the stereo sub setup!

So you have your front mains set to "large" and your surrounds set to "small", and are routing the LFE + surround bass to the DBX subwoofer?

Duplicate post.....

[This message has been edited by soundhound (edited April 13, 2003).]

Afcourse my mains are not as good as your mains, but I love them for music....

Yes, the surrounds only go to about 80Hz flat, so anything below drops to far off to be felt in conjunction with the fronts.

For the previous poster, the remix option is available in may receivers/pre's that allows you to set the various speakers to small and then the bass will be redirected to the LFE channel for each of those you set to small as long as the remix option is active. In my case, since I do not have "full range" surrounds and rears, it is ideal for me to remix the sub frequencies from those into the LFE channel.

alphanstein:

You have come up with a good option for those who have one sub, and also have "large" front mains!

A further question comes to mind for those familiar with audio mixing for Stereo (for current most music and the stereo only film tracks) and mixing for 5.1 (for some recent music and most current film):

When mixing for stereo, with or without surround sound encoding, everything is in those two tracks, including any added LFE. It is up to the consumer and his or her equipment to replay as stereo or ‘decode’ surround sound. This presents a not-as-complex situation for low frequency signals and the use of 1, 2 or 3 subs.

Now let us consider 5.1, and perhaps other discrete multi-channel methods. According to SH, the FL and FR of 5.1 will not contain the LFE signal, although the LFE may contain the lowest of the FL and FR music information for low-end reinforcement. Bossobass appears to indicate that the L and R will contain the LFE. Is there a contradiction here? Or can a distinction be made between the L/R signal of stereo and the FL/FR signal of 5.1 in that L/R contains all low frequency information and FL/FR does not? In other words, if one were to compare the L and R signals of stereo out with the FL and FR signals of 5.1, one would find quite a few differences? And, if there are differences, are the differences with regard to stereo vs. multi-channel for film different from the differences between stereo and multi-channel for music?

Yikes!

Good question bestbang4thebuck. I am thinking of using 3 subwoofers, one each associated with the FL, FC & FR to give me full frequency response from 20Hz to 20KHz on these channels. If I set my 3 front speakers to large and do not use a sub on the .1 channel will I be missing anything? I wish that the Outlaw manual would cover all of these situations or is there some other generic document that covers this stuff? Thank you ---- Thank you very much. Reed

in the setup for stereo subs that SH suggests, the sub is set to 'no'.

that means that the LFE is being summed with the redirected bass from any speakers set to 'small' and sent to the front lreft and front right speakers.

SH then suggests splitting the signal with an external crossover, low pass sent to the sub and high pass sent to the front speaker.

i contend, simply, that with this setup, the summing of LFE signal with the bass from the FL and FR, plus the bass from any speaker set to 'small', negates the stereo bass effect in multi-channel formats.

rghinton: if you set your sub to 'no', and your FL, C and FR to 'large', it will work fine. you will, however, have the LFE signal, split equally, sent to those speakers also, along with any redirected bass from the satellites (if they are set to 'small').

there is a huge difference between stereo and multi-channel music:

1. stereo has only 2 channels of signal. even if you use BM and a sub, you are only getting low pass filtered bass into the sub.

2. multi-channel soundtracks have a discrete LFE channel that is limited to 120 hz. it is output through the 950's SW output, along with the bass from any speakers set to 'small'.

3. multi-channel dvd-a/sacd have a discrete 6th channel. some discs do not use the channel at all, some use it for full range signal and some use it for LFE signal.

for the record, i agree with SH's setup, with 1 small difference. i believe the LFE channel should have it's own output, filter and slope options and 360 degree phase adjustment option, sent to it's own sub/amp. the LFE sub/amp should have a high pass output for a satellite to be used in the case of full range signal in dvd-a/sacd formats. this way, you get full benefit of the .1 channel in any multi-channel format, and the stereo subs will work measurably better without .1 signal contamination.

If a system was set up with the FL, FC& FR using sub woofers with electronic crossovers and setting the speakers to large in the 950 then each of the 3 front speaker channels would be capable of full frequency response. Any two-channel source or multi-channel source would have full frequency response in the 3 front channels. For the ultimate system, I would think that a 4th subwoofer only channel should be added for LFE with sub set to "yes" in the 950. This would send any multichannel movie LFE to the 4th subwoofer channel. Since I do not fully understand how various formats (stereo music, two channel movie, DVD 5.1 movie, DVD-A, DTS, etc., etc.) are mixed, does this seem logical? By building a system in this configuration, it seems to me that it would play every format without reconfiguring subs or 950 switches. The 4 subwoofers would not be there to blow the room completely apart but to put the sound in its proper location. I would assume that the 4th subwoofers placement would not be as critical as the other 3. The 3 that are associated with the 3 front channels should be as close to the 3 front channels as possible. I would like to hear the three front channels with full frequency response. I am just in the planning stage at this time but I value everyone’s opinion. Thanks.

While I agree with your final conclusions, I think your approach can be questioned. First, the Newtonian laws you reference refer to inelastic collisions; air is very much an elastic medium and its compressibility does affect the energy transfer (albeit considerably less than it might under other conditions). Second, you seem to infer that a driver's distortion-limited X(max) is defined by its suspension. I don't think this is the case nearly as often as you might think. Rather, the distortion-limited X(max) is defined by the driver's motor geometry; the suspension, hopefully, serves primarily to keep everything in line. And even in the lowest-compliance designs, where the suspension supplies a significant portion of the damping, it can behave in a remarkably linear fashion if properly implemented.

I agree that the advantage enjoyed by the larger drivers results from the shorter stroke necessary for a given pressurization, but I'd argue that it derives primarily from motor geometry. The increased X(max) required for the smaller driver to yield an equivalent pressurization would require, assuming equal gap heights, a longer voice coil. This creates two problems. First, the lower gap height/X(max) ratio of the smaller, longer-throw driver means that the BL will drop off much sooner and more quickly than it would with a larger gap height/X(max) ratio. And it will take the motor's ability to control the cone's motion with it; increasing distortion at a given level. Second, the longer voice coil contains more wire and, presumably, more turns than its shorter counterpart. And since this greater number of turns is moving through a longer stroke, thereby breaking more flux lines, the back-EMF increases considerably, further diminishing the driver's output for a given (open-circuit) input.

Or I could be completely wrong...

The collisions I used illustratively ARE ELASTIC collisions: where both momentum and kinetic energy are conserved. Although air is not an ideal gas, where collisons are close to ideally elastic, it is close enough for this discussion.

What I stated in my post was an attempt to illustrate some priciples that place an upper controlling bound (elastic collison is an upper bound) and yet give some explanation (not intended to be exhaustive) on why things are the way they are.

In my comparison of a large woofer and a smaller one, the part that says:

"...two woofers that have identical motor assemblies..."

will allow for the larger coned woofer playing at the same spl output as the smaller woofer to be producing lower distortion due to taxing the suspension less and, as you state, less distortion due to the (identical to the smaller coned woofer) motor operation more linearly.


Paul




[This message has been edited by Paul J. Stiles (edited April 18, 2003).]

Nothing could be further fron the truth. Carver Sonic Holography is based on crosstalk cancellation. There is a similar mode, called PANORAMA, in Lexicon processors which does crosstalk cancellation for 2-channel sources; albeit with much more sophistication than Sonic Holography.

Bass Enhance works by constantly varying the phase between the low frequencies on opposite sides of the room. This helps externalize the in-your-head, mono-sounding bass often found in studio recordings (especially pop music); makes it sound more like the bass you hear at live acoustic events.

Taking advantage of Bass Enhance is simple: you need two subwoofers placed at opposite sides of the room. Ideally the subs should be directly to either side of the listening area, but I've heard good results with the subs placed in the two front corners or anywhere along the side walls. The closer to the room centre line the subs are, the lesser the effect. With flexible placement allowed, Bass Enhance never "requires PRECISE placement of both speakers and listener's ears."

For more information, read the first few pages of the following Bass Enhance FAQ (quite interesting)...

http://www.smr-group.org/pdf/Bass_Enhance_FAQ.pdf You guessed wrong; the Bass Enhance feature is not dependent on multiple subwoofer outputs. The MC-12 is the only Lexicon processor with multiple sub outs. More than for Bass Enhance, these outputs are actually designed to allow MC-12 users to treat derived bass and discrete bass as separate entities. EVERY OTHER Lex processor (including their new MC-8) has a single subwoofer output; yet they ALL have the Bass Enhance feature (a feature that predates the MC-12 by a number of years). On the contrary, LFE content is precisely what Bass Enhance was intended to be used for. The .1 LFE channel contains mono bass that has the potential to be perceived as coming from inside the head. This content is perfect for splitting into two channels and applying Bass Enhance in order to externalize the sound for more enveloping bass. This makes absolutely no sense whatsoever. What does a process to externalize bass perception have to do with a discrete Low Frequency Effects track? Both co-exist quite well in Lexicon processors and aren't at odds with each other, either conceptually or in practical implimentation.

Best,
Sanjay

this is from the sited FAQ article:

"You might be tempted to use only 2 subs-one at each side-and eliminate the third LFE sub, since Bass Enhance will route LF to the sides. Be aware, however, that this strategy entails the following limitations:


...In 5.1 recordings, you will lose the LFE channel since it is not used in Bass Enhance processing..."

so...please tell me what i'm missing here?

also from the same article: "...Bass Enhance processing is predicated on those[laterally placed subs] being located to each side of the listener. It never hurts to experiment, but moving the side speakers fprward or backward more than 15 degrees (1-2 feet) will likely compromise the effect past the point where it's beneficial to use it."

as far as the over simplified explanation of carver's holograph generator, which is not crosstalk cancellation (as well as the limited explanation of dr. G's bass enhance process), my understanding of the 2 systems pinpoints the arrival times of sound from 2 sources as the basis for both.

whether or not you use phase, crosstalk or split signal/delay, you are doing basically the same thing, which is psycoacoustic processing using time-arrival manipulation.

dr. G admits that the process is very room-dependent, but offers no explanation as to why that is so. i've offered one for you...placement of speaker systems and ears is critical. you may feel free to prove me wrong.

bass enhance (which only works with a center-placed LF signal, and not with the stereo-recorded bass as described in the beginning of the thread, and is nothing more than an alteration of the source to change it to suit a particular whim...and not with very much success at that) is of little significance to me. therefore, i have no desire to purchase the white paper to fully understand the process.

my position on the importance of having a discrete LFE system to multi-channel audio is the result of many hours of research.

lexicon mentions 1 advantage in the manual, stating that the "more demanding LFE is separated from the 'crossed over' bass", allowing for 'smaller' subs to be adequate. (BTW, this in itself is reason enough for all pre-pros to offer a discrete LFE output with it's own processing options). the 2nd advantage they list is that of being able to level adjust the LFE separately from redirected bass.

unfortunately, they haven't explored the other numerous advantages (or if they have, they haven't made them public), such as arriving at production and labeling standards, as well as better reproduction options.

[This message has been edited by bossobass (edited April 20, 2003).]

[This message has been edited by bossobass (edited April 21, 2003).]

You're missing clarifications about Bass Enhance that came from Lexicon after this FAQ (which is not an official Lexicon document) was written. Not your fault, but it is the reason why I specifically suggested reading "the first few pages" of the FAQ. This newer information is also why I stated things that were contradictory to statements made in the last few pages of the FAQ: e.g., subwoofers need not be directly to sides of the listening position in order to take advantage of Bass Enhance. Also, you don't lose the LFE channel; it is simply folded into the derived bass being sent to both subwoofers. In fact, you don't even lose control of the LFE content; even when it's not being sent to its own dedicated subwoofer, Lex processors still allow the user to control the volume of LFE channel (discrete bass) independently of the subwoofer (derived bass) volume. Oh yes it is, and that's all it is.

From a 1998 interview that AIG's Gordon Brockhouse conducted with Mr. Carver himself:

GB: Is sonic holography essentially crosstalk cancellation?

BC: Yes. The crosstalk cancellation has been adjusted to produce a realistic presentation on regular stereo recordings. Years ago, Harry Pearson wrote a wonderful series of articles on generating a soundstage with a stereo system. What you want is a sense of layered depth on a soundstage that extends behind the speakers and is wider than the speakers. I've adjusted Sonic Holography to really give a soundstage in spades using Harry Pearson's treatise as a model. In real life, for every sonic event we have two sound arrivals: one for the each ear. Every time I snap my fingers, you hear two sounds: one in your left ear, one in your right. In three-channel playback, every time I snap my fingers, you might hear six Ä one in each ear for each of the three speakers. Those unwanted sounds need to be cancelled if we're to generate a replica of real life.

You can read the entire interview here:

http://www.audio-ideas.com/interview/carver.html

The Ambiophonics web page also discusses Sonic Holography, and other crosstalk cancellation technologies:

http://www.ambiophonics.org/welltuned.htm

"Polk, Carver and a few other companies took up the challenge of spatial realism in the "80s by, for example, supplying the right speaker with a "shadow" version of the left speaker's sound, timed and tonally shaped so that it cancels it at the right ear. Among the limitations inherent in Polk's early "Stereo Dimensional Array" and Carver's "Sonic Holography" techniques is the fact that the shadow signal not only appears, in this case, at the right ear, where it's needed, but also, at the left ear, where it's decidedly not. Modern digital processing, like that used in the "Panorama" in Lexicon's CP-series surround processors, can cancel this new distortion by supplying the left speaker with a shadow of the right shadow, then the right speaker with a shadow of the left's shadow of the right's shadow. It sounds crazy, but it works rather well, considering it really a new take on the old cat- chasing-its-tail theme, an provided you keep your head in just the right spot."


Also see the description of Sonic Holography here:

http://www.bmwworld.com/audio/carver.htm So what? Dialing in speaker distances, during initial set-up of a pre-pro, uses "time-arrival manipulation" (signal delays) to give the psychoacoustic impression that all your speakers are the same distance away. Does that make time alignment the same thing as Sonic Holography or Bass Enhance?

I don't understand why you continue to insist that Sonic Holography and Bass Enhance are similar. Bass Enhance does not generate ANY crosstalk cancellation signals. Listening space parameters such as room size, bass modes, and surface reverberance all serve as perceptual cues contributing to realistic bass. A room where all these parameters are contributing to terrible bass response could easily swamp the effects of Bass Enhance (just as an overly reflective or oddly shaped room can kill proper soundstaging and imaging). Elsewhere, in rooms where asymmetry and/or other factors contribute to naturally "stereo" sounding bass, the Bass Enhance circuit will do very little to improve the situation. I mean, the stereo effect already exists. It is rooms and set-ups, which conspire to create monophonic sounding bass, where Bass Enhance will really help.

However, room interaction is not the same thing as precise placement of speakers and listener. They may work off each other, but they are separate parameters. To that end, Bass Enhance is less affected by imprecise placement than it is by the contributions of the listening room. Truth be told though, the effects of Bass Enhance are most dependent on the recordings. I've heard well recorded live classical music where Bass Enhance's effect was negligible. I've also heard studio pop recordings where the effect was very pronounced and easily noticeable. Bass Enhance works with more than "a center-placed LF signal". It works with stereo bass too, especially in situations where a bad room is reducing the effect of well recorded stereo bass. Keep in mind that Bass Enhance is simply a tool to correct problems that may occur when playing back audio in less-than-optimal, real-world rooms. Nothing more, nothing less. For what it sets out to do, it is extremely successful. But you would have known that had you ever heard the effect. And with all due respect to your many hours of research, your "position" is of zero significance to me. I simply posted in this thread to correct inaccurate statements you made about Dr.G and Bass Enhance. I'm not (nor do I have any interest in) debating the importance of a discrete LFE system. I'm confused by the second advantage that Lexicon apparently lists in their manual. Follow: take any Lexicon processor, hook it up to only 2 main speakers (no sub) and play any source with a .1 LFE channel. The processor will fold down any number of channels into two, and mix in the LFE. However, the user can adjust the LFE level; there are separate parameters for discrete bass (labeled LFE Mix Level) and derived bass (labeled Subwoofer Level). Agreed, they haven't. But they may not have that sort of clout in the industry.

Best,
Sanjay

[This message has been edited by sdurani (edited April 21, 2003).]

though i appreciate the links, i've owned a C-9 since it's first arrival. in fact, my manual is hand written and illustrated by BC. i understand the process implicitly.

to clarify, it's interaural crosstalk cancellation. 'crosstalk cancellation' implies that there is something wrong with your equipment that needs corrected.

on the other hand, i don't understand bass enhance any more than i did before your posts and, apparantly, the FAQ article actually contains wrong information on the subject. i think that if it's all you think it is, the manual might have given the subject a bit more ink than the paragraph that 'covers' the subject.

if you have the ears to be able to properly level adjust and select the proper LP point and slope for, in any given multi-channel format, the LFE when it's summed with redirected bass into however many subs, then you have extraordinary ears. and, it's simply unnecessary to attempt.

our viewpoints here are basically opposite.

soundhound's original post describes a method to best reproduce a stereo mic'ed bass signal. i agree with that method, and any method that best plays back the original content. bass enhance seeks to alter a studio mix of direct-injected bass so that it sounds more like a live recording...not my preference. just as misguided, would be an attempt to place the bass signal of a stereo mic'ed mix into the 'center of your head'. the subject is reproduction of stereo bass, not post production creation of stereo bass. thus, my comments.

bass enhance is well enough documented by it's owners to convince me of it's limited success. to imply that it is not at all placement critical is incorrect.

lexicon is at the top of the heap, worldwide, in the field of reverb and delay processing on the production side. you underestimate their clout. certainly, at least, they have as much clout as apogee's rich elen.

i personally believe that the MC-12B is the best pre-pro available today. one of the reasons is the LF output config and processing thereof (bass enhance notwithstanding).

soundhound has said that he would prefer multi-channel audio be produced in a 5.0 format. that makes more sense to me than to say summing the .1 channel with redirected bass is perfectly fine. THAT makes no sense whatsoever.

I was using the term 'crosstalk cancellation' in the same exact way that both Brockhouse and Carver himself were using in the interview I cited. Maybe they were implying that there was something wrong with Carver's "equipment that needs corrected"? The manual is probably the wrong place to look for a thorough explanation of Bass Enhance; after all, it doesn't give much "ink" to how LOGIC7 works either. To be fair, it is just an operational manual (with a lot of ground to cover) rather than a 'theory and design' white paper.

Since you claim that Bass Enhance is "taking a page from bob carver's holograph generator", then could you please provide some documentation that shows where BE generates interaural crosstalk cancellation signals as part of its process? Yes, Bass Enhance is simply a post processing option specifically for situations where the you don't have the type of recorded bass that soundhound's original post described. It's like Pro Logic II: many people prefer not to use it, especially at a time when more and more discrete multi-channel recordings are being released (movies and music). However, this misses the point that PL II is an option specifically for situations where you don't have a discrete multi-channel source.

Ultimately it does come down to personal preference; some people like the effect, others don't. Understood. As I said before, I have no argument one way or the other with your position on the subject of stereo bass reproduction. I was simply responding to particular comments, such as your accusation that "dr. 'G' spent too much time developing bass enhance." Nothing personal, but I felt that bold statements like that needed addressing. What documentation discusses the relative success (or lack there of) of the Bass Enhance process? Which is why I never implied that it was "not at all" placement critical. However, not everything affects Bass Enhance equally. While it varies by situation, in most cases BE is more dependent on the original recording and listening room than critical placement of subwoofers. I'll defer to your better knowledge of Lexicon's industry clout. In which case, their inaction implies that the matter has little to no interest for them. It makes sense to me because, in the artificial construct of home audio playback, compromises sometimes have to be made. Most consumer audio systems don't have a dedicated LFE subwoofer that can afford to sit idle when no discrete .1 channel is present. Sorry, that's the real world. In those situations I welcome the option to sum LFE content with redirected bass; especially where I retain independent control of the LFE and the redirected bass.

Whether it makes sense to you or not, I prefer having these options now rather than waiting in hopes that the industry will someday adopt some sort of discrete LFE system.

Best,
Sanjay



[This message has been edited by sdurani (edited April 21, 2003).]

fwiw, i'll give it a (cursory) stab...

bass enhance is a process that uncorrelates, or decorrelates a correlated LF signal by applying a constant phase shift (i'm guessing quadrature, but i simply don't know the degree value) to the signal in each of 2 channels. this serves to add a spatial psychoacoustic quality to some source material in some rooms.

hologram generation applies a fixed time delay to each of 2 signals and routes each to the opposite speaker (actually adding crosstalk).

though 1 widens an already psycoacoutically spread sonic image and the other widens a psycoacoustically narrowed sonic image, the end result with both processes is that the signals are delayed as to arrival time to the ear from 2 sources in a controlled manner to give the illusion of a wider or deeper or more 'live' source. in fact, someone with the inclination should try a C-9 with stereo subs...it may even work better, as bass enhance lessens bass output.

as for documentation of the success of bass enhance, i read evey post i could find using "bass enhance" in the SMR search engine when i heard of the feature a while back. there were numerous posts with words like 'exasperating', 'my back is killing me from moving these subs', 'very source dependent', 'not everyone likes it', 'doesn't work in every room' 'doesn't seem to track as well as...', etc., etc. this, to me, is far from resounding success.

i apologize for any undue 'boldness' i may have conveyed in my posts. i assure you, i meant none. i find it difficult to express myself with only a typewriter as the means. i've read many of your posts, here and otherwise, and have always found them to be accurate and helpful.

i've been a fan of dr. g and lexicon for years. as he puts it, he was dragged kicking and screaming from the pro side to the consumer side. i don't think it's that lexicon isn't interested in influencing the industry with it's unique properties. i also don't think they haven't tried. (logic 7 as an encoded format comes to mind). in the case of the merits of a separate LFE output, i honestly believe that it was born of a way to increase the effectiveness of bass enhance, and lex really hasn't explored the many other benefits. i could be wrong, that's why i used the word 'maybe'. in re-reading it, i can easily see how it may have been mistaken to be flip or condescending. again...apologies.

to me, logic 7, DPLII, bass enhance, sonic holography, etc., impede the progress of discrete, multi-channel audio. that would mean i'm not a fan. i know you like these modes, so...i'm apologizing in advance for any future dumb ways i may convey my thoughts.

This may come down to how we each view the two processes: I see the similarities you mention, but I see greater differences. Yes, both processes are trying to widen the soundstage, but then so do other processes, like matrix decoders. This doesn't mean that LOGIC7 is the same thing as Sonic Holography or Bass Enhance.

Besides, I think the differences are significant. Holography uses crosstalk cancellation (Carver's words), fixed phase, exacting placement and specific delays. Bass Enhance doesn't use any of these technologies, relying instead on constantly shifting the phase (from 60 to 90 degrees) of the low frequencies between the speakers on the left side of the room vs the right side.

The effects of Holography are more noticeable as you use less monophonic recordings. The effects of Bass Enhance are more noticeable as you move towards recordings with more monophonic bass. The results are also quite different: Holography produces better localization with almost shockingly precise imaging in the front soundstage; Bass Enhance actually does the opposite, as bass becomes less localizable and more enveloping.

Going back to your original point about precise placement of speakers and ears: that may sometimes help Bass Enhance but it is an absolute neccessity for Holography. Confusing the two processes will result in placing a requirement on Bass Enhance that is not really, well, required.

As mentioned before, Lexicon has a mode similar to Sonic Holography, which does have all the requirements you've described: users have to dial in distance, angle and position of the listener relative to each speaker. Talk about precise placement! None of this is required with Bass Enhance, as there is nothing in the menu for setting it up. Also, the Holography-like "effect" can be adjusted over something like 62 steps; Bass Enhance is simply and on/off parameter. Again, the two processes are significantly different. I've read similar quotes from people trying to locate and intergrate a subwoofer (or worse, multiple subs) seamlessly with the rest of their speakers. This hasn't made me feel that the addition of subwoofers to home theatres was a less than successful idea.

Maybe we're using the term "successful" to mean different things. Properly set up, Bass Enhance delivers as advertised. I don't see what's particularly unsuccessful about that. Griessinger is definitely an interesting guy. Like many scientists, he can sometimes be an odd bird, especially in person. Lately he's been so obsessed with optimising LOGIC7 for cars that Lexicon, once again, has to drag him kicking and screaming to work on their home theatre products. I don't think Lexicon has ever really made an effort to push for LOGIC7 encoding for 2-channel material. Ironically, due to the equpment used in one mastering house (MiCasa Productions) there happen to be more L7 encoded DVDs than EX encoded titles. More a fluke than anything Lexicon actively attempted to do. BTW, these soundtracks decode incredibly well on the Outlaw 950 using the PL II CES modes.

As for influencing the industry as far as a discrete LFE system is concerned, it may simply not be a high priority for a company that does the kind of work that Lexicon does. Keep in mind that their speciality is signal processing (turning 2-channels into 7, turning mono bass into stereo, etc). Just a guess, but they seem like they'd put more effort into figuring out a proprietary solution to an industry problem rather than try to change the industry itself. From what some of the folks at Lexicon have told me, the reason behind the separate LFE output was to allow users to treat derived bass and discrete bass as separate entities. For example: the two sub outputs can be run as dual-mono, real stereo (bass filtered from all the left speakers vs all the right speakers), or even have Bass Enhance applied to the signal. In comparison, the LFE output is simply a passthrough; not even a crossover in the signal path!

Interestingly enough, I heard Bass Enhance work well in a system with no subwoofers. While on a quest for suitably "mucical" subs, a friend of mine temprarily set up his system with 6 floorstanding speakers and a small centre channel speaker (standard 7 speaker placement). While the floorstanders were by no means full range speakers, they had enough bass to show off Bass Enhance. Ultimately, Bass Enhance is not as much a process for subwoofers as it is a left bass vs right bass process. Likewise, apologies for anything I posted that may have come off as harsh. As I said in my previous post, nothing personal meant; even (especially) when our views are at odds.

As for surround processing, yes I'm an obvious fan; mostly because I use my processor 80% of the time for music listening, most of which is 2-channel CDs. It's been almost a decade and a half since I've listened to 2-channel material using only 2 speakers. I don't hear everything in the real world between two points in space in front of me. At this point in my hobby, I find it very distracting to listen using only 2 speaker. I guess that makes me the anti-purist audiophile?

Is surround processing an impediment to discrete multi-channel? I'm not so sure. Keep in mind that the best matrix decoders (LOGIC7, PL II, Circle Surround II) came out after DD 5.1 was already established. The argument could be made that discrete multi-channel is having a bigger influence on surround processing, rather than the other way around. Once consumers get a tase of discrete multi-channel, they start to want that same sound for everything in their library. Companies respond by creating surround processing that tries to bring 2-channel legacy recordings as close to possible as the discrete multi-channel experience.

One place where matrix decoding may be hampering the desire for more discrete channels is with Griesinger himself. His "ideal" playback system has 5 speakers up front (main L&R pair, centre, a pair at the first reflection points), 2 side speakers, 2 rears, 2 overhead speakers and a pair of subs. However, he doesn't advocate going beyond 5.1 discrete delivery channels for his 11.2 channel playback system. The bulk of the channels will be matrix encoded and recovered upon decoding during playback. If he didn't have such strong convictions towards processing, he'd probably be advocating more discrete channels (full range and LFE).

BTW, don't know if you've seen these yet, but for some interesting reading, check out this interview with Dr.G:

http://www.smr-home-theatre.org/Lexicon/dg_qa1.html

As well as the good doctor's own website:

http://world.std.com/%7Egriesngr/

Best,
Sanjay




[This message has been edited by sdurani (edited April 22, 2003).]

this is the correct way to treat the LF of a multi-channel audio system.

i've played electric bass for some 36 years. any recording of electric bass is done DI, whether live or in the studio. though i appreciate someone's desire to use stereo bass reproduction (though the choice of good source material is relatively small), and i really don't care what sort of matrixed synthesis of the original source someone may prefer to design, manufacture or use at home (unless it was MY recording), i don't see the requirement of 2 outputs for redirected bass. nevertheless, it costs next to nothing to implement, so why not?

the really important thing is the discrete LFE output to it's own system of filters/slopes/delay/sub/amp and level control. as soon as you understand the potential of the 6th channel, you know that you shouldn't just sum it with redirected bass.

the demand on a sub is drastically reduced for movie formats. add a HP filter and you have a full range channel for dvd-a/sacd. use a LP point and slope that best suits LFE while not destroying the critical adjustment needed to reintegrate redirected bass. significantly reduce intermod distortion. ease placement problems by reducing the size of the subs. have a 'musical' sub and a 'movie' sub in the same system. be able to calibrate the LFE in relation to the redirected bass levels...on-the-fly if need be. invent new instruments. and, yes, even matrix the 6 channels instead of 5.1 (for those who like such things ) into gozillion.1 without changing anything but to add an LFE output. any one of these points warrants the output. it costs nearly nothing. lexicon is right for doing it and the 3 points they bring up to justify it (less demand, level adjustment and separating it from derived bass) are dead-on correct.

one more thing...once you've 'enhanced' my bass lines, promise you'll stop there and not compress, add reverb or flange or run your subs 6db 'hot'??

Many thanks to all that have contributed to this topic... this has the richest, most informative. and most relevant discussion I can remember in any audio forum. Although I am not shocked, I am in awe of the level of technical knowledge and uncommon sense displayed by so many of the Gunslingers here.





I have some basic questions concerning the Stereo Sub set-up, and the configurations suggested by SH, Bossobase and others...

Question #1: Does the inclusion of an Outlaw ICBM provide additional benefits to a Stereo Sub configuration, over and above the use of the 950 alone? The LFE Mix control seems to be one benefit, but it becomes irrelevant if the LFE channel is made discrete.

Question #2: Assuming the mixing of the LFE signal with redirected bass to Left and Right Stereo Subs is potentially as serious as bosobase suggests, would it make sense to configure a system with three (3) subs? Two subs dedicated to the redirected bass from the 5.0 signal; and one (possibly more) dedicated to the LFE (0.1) signal...

My configuration currently uses stereo subs which are located directly adjacent to (and aligned with the face of) Front Left and Front Right floor standing speakers. I am using an ICBM to send redirected bass to the Stereo Subs, and mix in the LFE signal as it is designed. Otherwise, it is similar to the set-up that SH suggested in the opening post.

Question #3: Is a potential solution (system improvement) as simple as this?...
a) Unplug the LFE input to the ICBM, and stick it in a new dedicated Sub.

With all speakers set to Large, everything should work, with no cross contamination between the full range (up to 150Hz) LFE signal, and the redirected bass to the Stereo Subs (which are crossed over at 60Hz). Yes? No, I think...

Question #4: How to overcome the Outlaw 6-Channel Bypass Mode "base management" algorithm?... The 6-Channel Bypass Mode sums redirected bass (at a fixed 80Hz crossover point) from the 5.0 channel signal and mixes (sums) this with the LFE signal. The full range 5.0 signal can be sent to the speakers by turning Bass Management "Off," but the Outlaw LFE output is not suitable to the purpose of separating the LFE from the rest of the system signal as it still contains the under 80Hz signal from the 5.0 channels. What to do, what to do? Perhaps... but I don't know...
a) An A/B switch for the low level LFE signal that allows the user to bypass the 950's Sub I/O processing section(s), therefore connecting the dedicated LFE sub directly to the source. But... this would take out the 950's control of the LFE channel volume. What a mess! The LFE signal level would need to be constantly adjusted when changing the volume in 6-Channel Bypass Mode and then again when switching back to the other source modes.

It would probably easier to bypass the Outlaw 6-Channel Bypass Mode altogether. Perhaps someone could suggest a more simple product alternative that could perform this purpose... or a better overall system configuration? I am aware that there are Pre-Pro's that allow the user to maintain a discrete LFE channel, with separate outputs for stereo subs dedicated to redirected bass. This is a nice feature of Lexicon's MC-12(B or no B) and the new Parasound Halo C1 unit.

I am with other Outlaw owners who are looking forward (with our hands together) to the next generation of the 950. Bass management that provides significantly more flexibility in system configuration would be first on my wish list. The ability to assign individual settings for each source a very close second. Even though I don't like the logo... I would silk screen it on my front door if the Outlaws keep their eye on performance enhancements that we can enjoy in a dimly lit room.

Again, thank you all for interesting reading...


P.S.: I have found that it becomes especially beneficial to have good sound isolation spikes for the sub and the Main Left and Right speakers when they are placed so close together as they are in my system.

[This message has been edited by AGAssarsson (edited April 29, 2003).]

As long as your subs can take the combined re-directed bass in addition to the LFE, there is no problem with recombining the signals. There is a disadvantage to using a dedicated LFE sub however, and that is that the LFE will be only reproduced by one sub instead of two. I prefer to have the added oomph of having the LFE reproduced by more than one sub personally, in addition to the room mode averaging afforded by multiple subs.

The ICBM is a workable solution, however I think (I could be horribly wrong) that the stereo sub crossover ability is limited to a fixed 80Hz frequency.

Am I missing something or is not the Center Channel just as important as left and right? I would think that the ultimate would be to have Left Sub, Center Sub, Right Sub and LFE (.1) Sub.

For multi channel audio discs, yes, the center has the same low bass requirements as the other front speakers. For movies, in practice, very low frequencies are kept out of the center speaker because the mixing engineers need to keep the channel open for dialogue, which is the most important element in a film's mix (from a mixing standpoint). Low bass eats up the available headroom in a channel, which is the main reason for the LFE.

Stereo subs operating with the left and right fronts (with center and surround bass re-directed) is a reasonable compromise given the nature of most source material.

The ICBM has a switch that allows the user to select between mono or stereo sub output from the L & R RCA sub terminals. In stereo mode, the Left Sub gets a full lowpass signal from the Front Left and Left Surround channels, and half the signal from the Center Front and Center Rear channels. This is explained in the ICBM Manual (Page 14, pdf file available @ this site).

I have tested the crossover response, and the ICBM does permit independent crossover settings for the following channel groups:
a) L & R Fronts (2 channels)
b) Center Front (1 channel)
c) L & R Surround (2 channels)
d) Center Rear (1 channel)

The crossover choices are 40Hz, 60Hz, 80Hz, 100Hz, 120Hz, and Bypass for each channel group.

The effect of flipping the switch from mono to stereo varies significantly on recordings with good bass content. I believe many recordings have mixed (summed) bass content to the L & R channels, and therefore have defeated the opportunity for stereo bass. I believe this underlines SH's point regarding the splitting of a specific musical instrument's sound signal, which can happen because:
a) the listener definable Sub/Main crossover setting (where the Subs are located distant from the mains), and...
b) the arbitrary mixing point chosen by the engineers in the studio (where low bass is summed equally to L & R, assuming the sonic characteristics of the listeners speakers and system are not up to reproducing full range stereo signals).

As SH states... "The closer the notes being played are to the bass crossover frequency [or low bass mixing point], the worse this disembodiment of the fundamental from it's harmonics will be, as the phase difference between the two will be greater due to the higher frequency".

One example... The Talking Heads and TomTom Club have very good stereo recordings of low bass frequencies, with lots of electric bass and all kinds of drums. The benefits of Stereo vs. Mono Sub-woofing are very evident. With stereo subs, the location, image and phase coherence of each instrument provides a sense of realism that is significantly better than with the ICBM switch in the mono position.

While I have not perceived a problem with the lack of a discrete LFE sub (or subs), I believe that Bossobase's quest for independent LFE signal is a good one. In my opinion, it is like chicken soup... will it help???... it couldn't hurt...
but it will cost you.

Best Regards

[This message has been edited by AGAssarsson (edited April 29, 2003).]

answer to Q #3: if your ICBM is placed between the player and the preamp, then yes. you may, however, need a seperate preamp to boost the LFE signal from your player to your sub's amp.

adjustment of LFE volume separately is not that big a problem (actually, it's a good thing to be able to balance the levels properly, which you'll learn to do as you experiment). i do it regularly. my LFE preamp is set next to the player. i simply set the volume for each disc when i load the disc.

remember, this will only work with dvd-a/sacd. unfortunately, the player will output the LFE through both the analog SW out AND the digital out. this means you'll get LFE into the 950 when in digital modes along with LFE into the 3rd sub.

obviously, LFE summed with RB 'works'. it just doesn't work as good.

try the setup described in your Q #3 with 1 sub as a dedicated LFE sub and the other one as a redirected bass sub.

also remember that the added 'oomph' will still be there as multi-channel audio discs use the LFE channel (by and large) for that purpose. you'll still get the same signal into the 2 subs almost always. you'll just get full use of the LFE channel AND best reintegration of RB.

the ICBM has a glogal LP of 150 hz on the LFE channel, so try that first (disable your sub's x-over). i use a 2-way x-over on my LFE system, with selectable x-over points. it works great for a full range 6th channel as some sacd discs warrant it, and looking toward the future.

dial the RB sub to best integrate it with your sats. try 80 hz for all sats first, then venture from there as your sats permit.

wherever the 2 subs are placed, make sure they are both precisely the same distance to your ears.

this is a convoluted work-around, i agree. i also await the new outlaw having a dedicated LFE output.

finally, the discrete LFE assumes a good music sub and a good LFE sub are in the system, with proper phase, levels, x-overs, slopes, etc. no setup will make a poor system sound good. experiment. it's worth it.

Thank you Bossobase.
I will give it a try next month, when I can borrow a good preamp from a friend.

I have two Velodyne HGS15 Series 2 subs, so I think they are worth the trouble to test this feature. My speakers are large floorstanders, but I cross them at 60Hz, as they sound better. Ultimately, I will be getting a new sub for LFE, when Outlaw decides to put the dedicated LFE channel output on the 950 version 2.

I will let you know how it works… Thanks again.

sorry for this incorrect suggestion (long day). if you configure your LFE sub per question #3, you'll use your sub's x-over and bypass the ICBM.

I have owned Def Tech 2000's tower speakers( with "stereo subs" ) for years ( you either love 'em or hate them...) and use a "y" splitter from front L/R outputs of my pre amp (soon to be a 950) going to the 2000's "full range low level inputs" and the other part of "y" going to amp running the mid/highs for the 2000's. This is how Mr. Pelkowski from Def Tech has recommended me to set up my speakers for "true" stereo subwoofers. I love what I hear, and although I am certainly not an expert at the scientific reasons for it all, it sounds pretty darn amazing....(right now using Yamaha CX-2 Pre Amp..really nice Pre Amp by the way, and am keeping just to use the Phono outputs.... and Fosgate Model 4 Processor....)
this thread has (as usual) been really informative.....you Outlaws are the best when it comes to helping each other out with suggestions, etc....
just had major spine surgery and it is holding me back from upgrading right now ( I want to, I want to, I want to...I NEED to!).....
anyway....
first need to sell my old equipment on EBay or Audiogon...and move on up to the 950/770 combo.... boy, I cannot wait!!!!! I think stereo subs are worth it if you can do it, and once again have learned alot from these kinds of posts....Love this part of Outlaws website, and just had to chime in.....
better late than never.....
It's the only website I look at every day.....amazing stuff and amazingly intelligent gunslingers out there.....love it!!
well, anyhow,
Stereo subs are a big plus in my opinion....

Glad to hear you're enjoying you subs in stereo! I have heard of other DefTech owners who have gone this route and have the same result as you.

I, too, own the BP-2000's (original, not TL's), with the CLR-2000 center, BP-X on the sides, and a pair of BP-20's as rears. (BTW, I run a Sunfire Stereo into the mains and a Cinema Grand into the other five; plenty of power.)

I had the mains set to 'large', the center set to 'small', and the rears set to 'large'. I also use a second processor in 3-channel mode to extract a rear-center channel, split to two amp channels, to drive the rears.

I have the second processor's center set to 'large', and the mains (driving the sides, remember) set to 'small', so the surrounds' lows come from the rears, which do bass well. All of this means that only the center's lows were redirected to combine with the LFE channel into the subs.

I originally had the pre/pro's LFE out Y-split to the two low-level inputs, despite Def Tech's recommendations. When I put my gear into the 'hole in the wall', I replaced the links and ran the sub amps with the speaker leads, as I didn't have long interconnects handy.

Of course, I set my pre/pro's bass mgt. to 'no sub', and thus began running my subs in stereo. There was a distinct improvement in the bass quality, not just bass level. I know the LFE channel's signal was split to both subs, as a mono signal, but there was a new, distinct fullness.

However, the stereo sound above the X-over frequency still gave enough directional cues that even the deep stuff seemed to have direction. Since any speaker can reproduce more than one sound at a time, each sub could do half of the mono LFE and the stereo signals' own bass at the same time.

I've read several posts that either suggest, or say outright, that having a mono signal played through two subs ruins their ability to simultaneously reproduce stereo bass, with discernable separation.

Personally, I don't understand why that would be. As I said, a speaker can play more than one sound, so why can't two play stereo audio and a common bass? That's what every two-channel system does with a common bass sound anyway.

Anyway, I recently rewired my speakers again, by removing the links and running a new pair of interconnects, but this time, I used a full-range stereo output instead of a low-pass-filtered output, allowing the subs' LP filters to do the crossing-over, as recommended by Def Tech.

Guess what?! Another improvement in sound. A bit tighter and deeper. A casual play of a bass-test CD shows an increase at 30 and 20 Hz. I sometimes detect stereo separation in even low-frequency sounds.

Let us not forget that all channels are capable of full-range sound, even the LFE if the engineers so choose. There's no reason that 20-Hz bass couldn't be separately recorded in any two or more channels in- or out-of phase, and/or at different levels.

Anyway, I just wanted to point out that there's no technological reason that the non-LFE channels must be devoid of the same deep-bass sounds that the LFE usually carries. The LFE channel is intended for just that: Low Frequency Effects.

Sure, a redirected LFE channel will be mono, but there are plenty of directional cues (harmonics) in the remaining channels, as well as actual low-frequency content, that could certainly benefit from stereo subs, even if it's only a result of phase differences.

There's certainly no harm done.



------------------
Larry Fine
www.fineelectricco.com
My system

SH (et al),

(Think way back your original suggestion for configuring stereo subs at the beginning of this thread)

Question: Would the relatively long runs of IC, along with the high-pass on the subs (in this case 2 x SVS 25-31 PC+), audibly deteriorate the signal from the L/R outputs of the 950 in a way that connecting the 950 directly to the amp would not?

Thanks in advance.

Running the signal through the sub's crossover obviously requires that the crossover network be of good quality. I would not do this if your subs only have passive, speaker level crossovers. If the sub has line level crossovers, the best course of action is to just hook the system up for stereo subs and listen for any negative contribution from the sub's crossover. A call to the sub's manufacturer might give some insight into the quality of the crossover.

The Outlaw ICBM can also be used to do this setup, and it is of high quality.

I wouldn't worry about the length of interconnects. Just keep them away from AC power wires (a good idea no matter what the interconnect length).