SH:

Do you know this to be correct?
I would think this would make for a really bad bass sollution for people who have "not quite full range speakers" and want most of the bass information to come from the mains. ie... crossover at 40Hz or 60 Hz...

I have used the ICBM in stereo, and I don't believe that it overides the settings to a 80Hz default crossover.

Otherwise, I concur with your use of stereo subs, and admire the design of your system as a means to that end. I also wish to second your past comments that the overall power and envelopment of a 2 sub configuration is a significant sonic benefit over just one.

Thanks...
Allan

Allan:

I got the 80Hz figure from looking at one of the manuals on-line, but I certainly could be mistaken on this point. From what I gathered, you have the ability to adjust the crossover frequency with a traditional mono sub setup but if you flip the stereo bass switch, the crossover is fixed at 80Hz. I was thinking of possibly buying one and noticed this, but please correct me if I'm wrong!

From looking through the manual just now, it appears to me that the stereo subs still allow a user-selected crossover.

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review

SH:

I just spoke to Scott at Outlaw... he verifies that "Stereo Sub Mode" uses the same adjustible crossover settings as the "Mono Sub Mode".

In stereo, the ICBM sums all the Left channel low-pass signals with half of the center channel low-pass signal, and sends this to the Left Sub Output. Similar for the Right channel.

The ICBM also allows the LFE signal gain to be adjusted independently from the low-pass signal, which is a great feature.

One limitation of the ICBM is that you are limited to fixed crossover points (ie., 40, 60, 80, 100,120Hz, or bypass) as opposed to most Subwoofers that have a continuously adjustible crossover where you could choose 50Hz, or 43.752Hz if you so desired.

Allan

[This message has been edited by AGAssarsson (edited August 01, 2003).]

Thanks for the clarification. I probably got confused by the fixed crossover frequencies aspect. There was some reason I had to disqualify it from purchase though, but I can't think of it now.

snarf:

Welcome to the Saloon!

I've enjoyed reading your inputs. A couple of notes:

Sanjay is one of those guys about whom you could say 'It's not what he says, but rather, how he says it'. He's an avid fan of DPLII and Logic 7, as well as the Bass Enhance feature of the Lex PrePro. He's very knowledgeable on these and other subjects, but being quoted line by line with each quote followed but a reproval takes some getting used to.

On the question of derived (or, as I would rather refer to it, redirected bass) taken from the 5 sat channels and summed with a copy that is recorded on the LFE channel, Sanjay is correct. Whether or not they are reproduced by 5 full range sats and a sub (playing the LFE channel), or 5 speakers set to 'small' and a sub playing the redirected bass and the LFE copy, they are still reproducing what the engineer obviously intended. It is, in fact, double bass, but it's intended, and therefore called Low Frequency Enhancement.

Getting back to my greeting, there are many things you've posted that are great subjects for those who simply read these threads and never post and so I would take this opportunity to ask you not to part our company because you feel 'attacked'.

By all means, post away. You input is welcome and the reason I come here often. You're an obviously intelligent person who has a grip on some of this currently evolving medium that is multichannel audio.

Sanjay:

I've been meaning to ask you to try something for my sake. Since you are one of the few guys who seem to understand Bass Enhance, or seem to have done more than simply research it, I wonder if you might use a SACD multichannel disc and:

Connect 1 sub to LFE discrete out and 1 sub to reproduce redirected bass. Dial in the LFE sub until it appears sonically balanced and listen to a particular passage.

Then, connect the 2 subs with redirected bass and LFE summed with Bass Enhance engaged.

Tell me what you hear as the differences. I would very much appreciate the report, if you're so inclinded to try it (and, of course, if you have any multichannel SACD discs that you like).

I am here to learn as much as I am here to share my knowledge, experience and insights. It was fun, until now; I am indeed about to chime-out.

What seemed a fun discussion turned into a conversation about competence. The only way to earn credibility points - this conversation is apparently about winning something - is if you can answer trivia questions or show off by casually mentioning makes and models of full-bandwidth loudspeakers - I did mention B&W or Wilson Audio already, didn't I? - or titles of DVD-A discs which interest me the least - as if there are so many DVD-A titles already - or otherwise pee against some tree that is apparently relevant to the poster. Bashing is easy, but it says usually more about the basher than about the bashed.

If you need to know what my background is, then ask a direct question, but do not hide behind secret criteria that are irrelevant to the discussion to value the input. The encouragement from other posters is very much appreciated though, and I know that it is not chique to quit, but what is there to gain except frustration. What I encounter here is sheer lack of willingness to understand the issue from at least a technical point of view. If the willingness is not there, then let's stop. If the reason for the unwillingness is caused by my reluctance to 'pee against the tree' as defined above, so be it. If my arguments sound unbelievable, understand that bass management is a matter of logical science, not a matter of religion. The frustrating part to me is that I am unsuccesful to wade through the smoke screens, and that I am unable to explain why there is a need for regulation of the bass management issue. If my explanation of this issue is not clear, but you are interested in the matter, please dig around elsewhere, do DD under the professionals, and, as suggested before, read a book or two about the subject.

The 'high-end' world is mostly flushed with discussions about esoteric issues, which are fun to watch from a safe distance, but the subject of bass management should not have to become one of these subjects. The rules of the game are simple and straightforward, and are made to serve the consumer with a consistent sound balance that, once the loudspeaker configuration of the consumer is tuned, will work with every recording without adjustment. The need for these rules are there because the recording industry cannot and should not expect the listener to continuously make these adjustmens. We are talking about facts here. That not every engineer and high-ender is aware of the facts and rules is not surprizing, although somewhat alarming.


On the bass management subject again.

LFE is for effects, not for music or other content that is of value for the program. This is in some cases an artistic choice, and only in a very few cases a technical choice. If you have a sub and decent bass management then there is no need at all to double the bass information in the LFE channel. If you do not have a sub, same applies.

Some of you may have noticed that I made a mistake in my previous posting. There I explained the doubling of base between 40 and 80 Hz in situation B. While travelling it occurred to me that there is doubling of the entire DC-80Hz region, except that DC-40 is doubled in the sub (redirected bass+LFE channel) and the doubling between 40 and 80 Hz occurs in the sub AND the main loudspeaker. Quite a significant issue, as the phase response and loudspeaker color of that doubling may cause interesting psychedelic artefacts, depending on the specific components, loudspreaker placement and acoustics.

On the subject of the sound in the recording studio, I already explained that the engineer would in fact NOT pick-up on the unwanted doubling because he or she already KNOWS that the signal feed is doubled. Self-fulfilling prophecy, n'est pas (I can pee in French too)? It is in the 'dialing in' of the sub in the system in the studio that the engineer still listens to a balanced system that now in fact NEEDS the double signal feed (via LFE and redirected bass). This will in fact only sound half-decent if the cut-off to the LFE is set at the same frequency as the cut-off from the mains to the sub so the signal doubling occurs only at the subwoofer, otherwise you would get different loudspeaker drivers, electronics and signal paths driving the 'difference bandwidth' which, as suggested above, has the potential for weird effects. As you see, the discovery of my previous mistake has lead to a potential worsening of the sound quality in the studio environment. I sincerely hope that no-one still wonders why we need rules for bass routing and management...

Suppose for a moment that... (dream music starts) studios have different loudspeakers and different settings for the cross-over, then the resultant sound would be different every time, (music turns grimm) and even worse, not even a fine bass manager as our hosting company makes can make-up for that, because we have to tune the trapped bandwidth. What a mess would that be! Lucky for us studio's all use the same equipment and loudspeakers (dreamy music picked-up again). What a happy dream...

I may start a new thread with an old question I have about binding posts that still have not been able to answer.

For this subject I am done, unless relevant iterations come up in good spirit.


Snarf

I agree with your comments about SACD...I'm a big fan of the format.

I began my multichannel listening experience fully believing that the ITU standard (5 identical full range satellites, set equidistant from the LP and 1 sub for LFE) was the setup that would produce the best results at playback.

I soon realized that it doesn't work for the simple reason that low frequency reproducing speakers are very placement critical. But, so are the 5 satellites. The placement of the low frequency speaker must be experimented with in a given room, where the satellites have a very fixed spot and can't be moved.

The idea of stealing the bass from the satellites and redirecting it to a subwoofer then seemed a good idea because the satellites can be placed exactly where they are required to be and the subwoofer can be moved about until the best spot for it is found. Omni-direction of low freqs allows this to work.

Ahhhh, but then there was still the LFE signal. Once you adjust your subwoofer to optimally reintegrate the stolen bass into the soundfield from which it is stolen, you then have to suffer the summing of LFE into the same subwoofer.

To make matters worse, most pre/pro/receivers won't let you seperately adjust the slope/LP/phase/volume of the LFE. Only the summed signal can be manipulated.

If you buy a sub that's capable of withstanding the 121 Db onslaught of the Dolby reference level spec, it surely is worthless for music reproduction. Some software has a mild doubling of bass, some a brutal dose. Some have music soundtrack that will be summed with 'dinosaur footfalls'. Some even have full range info in the .1 track.

The answer really is simple. 1 sub for redirected bass and another sub for LFE. The LFE sub will have it's own preamp/processor with a crossover (not just a low pass filter), selectable crossover points, slopes, variable phase adjustment and a preamp that's optimized for LFE reproduction and provides unity gain from a player or preamp to a hi-fi amp or a pro sound amp. The high pass out of the LFE crossover can feed a 6th satellite.

You then set up your redirected bass sub to make your satellites happy while blending in the LFE sub as best suits the program.

Much less is demanded of each subwoofer. Intermod distortion takes a nosedive. The music lover is as happy as the HTphile. Heck, you can even mute the LFE if the double bass offends you. And, no more lost LFE because you choose a 40 Hz. crossover for redirected bass (though some preamp makers claim to send the full LFE along with any chosen RB low pass, it's really ridiculous to expect 1 subwoofer, or many, for that matter, to handle both signals correctly).

There are many more advantages to this setup, but the biggest one is in listening. Low frequencies are a beautiful thing when done right.

As an artist, please don't take away the LFE before we've even had more than a heartbeat's time to experiment. Anyone who tells me I can't write a dinosaur footfall into a piece of music or that there are no instruments but a pipe organ that have low frequencies (sheesh, I hate that one) is an arrogant fool with the imagination of an engineer.

I designed such a low frequency processor, had it built by Dr. Phil (Marchand), custom built each subwoofer for it's specific chore using proprietary parts from around the globe, tweaked placement, room treatments and circuitry, all the while charting and graphing the in-room results against the summed-signal subwoofer system.

But, as I said earlier...it's really in the listening in the end. A discrete redirected bass sub system (or 2, if you prefer stereo low freqs) along with a discrete LFE sub system is the simple answer in production of and playback of multichannel audio.

Don't slam the door shut before it's even been opened. BTW, my newly designed 1 string bass requires 2 people to play it. Wait til you hear THIS baby.

I've read recently that the omnidrectional nature of bass is not quite correct and has been repeated so many times since 1964 that it has been accepted as gospel. From what I remember offhand the original study noted that MOST people (blind study by the way) could not sense/hear the direction of low bass but the percentage of people who could increased as the frequency increased above 70hz.

I also run sound through two subs right under the mains but cannot understand (or did I miss it above) why no one really discussed phase problems which can occur when you split the bass signal to two subs--you can have some notes (depending on distance/position of the subs I believe) cancel one another out (except perhaps for some harmonics). Luckily my subs have a phase switch so when I'm watching movies with the combined .1 LFE I can flip the phase switch on one of the subs and double the LF impact in many scenes.

I don't pretend to be and expert and a little knowledge can be a dangerous thing but I think this is an issue that you're missing in this discussion. Soundhound mentioned phase issues monitored in the recording process but that wouldn't do anything for identical sounds played by two subs which cancel each other out because they may be out of phase (or is it in phase? I think out) due to their position.

Anyway, I just wanted to hear some feedback from folks who know more than me.

Up.