Hello,

How can hook up more than 1 subwoofer to the 950 model ? can it be done ?

I dont own one yet, just wondering if I can do it without daisy chaining them

Thanks

Kid

You need a splitter to make two RCA connections out of the 950 sub out. they sell them everywhere. here is a link to what I purchased, good quality, great price.
www.cobaltcable.com/product/y_splitter.htm hope this helps.

[This message has been edited by DNicely1 (edited August 11, 2004).]

Outlaw also sells a nice splitter.

No sane person needs more than one subwoofer.

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The Soundhound Theater

Soundhound- I'm glad you popped into this thread. (Maybe Boss O Bass will show too.)

*I've* also been thinking about 2 subs. The reason isn't output or low freq extension, it's flat freq response.

Let's see if this works:

http://img.villagephotos.com/p/2004-8/804255/sweetmains+subfullnoeq.jpg

This is an ETF generated plot of my low freq response at the listening position. Sub in the corner, 60 Hz crossover to the mains. I'm pretty proud that all the peaks are level, but I want to fix the suckouts. The only way I know how to do that is with multiple subs. ??


Kidtricky- There's another way to do mulitple subs too: you can use Y connectors from the RCA out on the 950. But you can also add another sub or 2 or more by using the speaker level connections from, for example, the front L & R speakers. You'd set the fronts as Large in that case, and let the sub do the crossing over.



[This message has been edited by Kevin C Brown (edited August 12, 2004).]

Some subs have both "in" and "out" line level RCA connections - allowing you to daisy-chain them together using the single sub output on the 950. I don't know why you would not go this route if it's available to you since, depending on the layout of your theatre, it can reduce your cabling costs. An admittedly rare feature unfortunately.

Jeff Mackwood

Wow, those are some healty dips! They point to strong room modes and two subs properly placed (by experimentation unfortunately) will help to smooth them out. Good luck.



[This message has been edited by soundhound (edited August 12, 2004).]

Wow, Kevin, good luck with those. During the advent of your second sub, why don't you try moving your current sub out of the corner? That'll smooth that curve out. My bet is that even with a second sub, you'll be moving the first one out of the corner anyway. I tried a corner loaded sub balanced by a second sub and I couldn't find a good place for the second sub to balance the peaks and valleys. When I moved the first sub out of the corner the balancing got a lot easier.

If a powered sub has both RCA inputs and outputs, note whether the output passes along the low frequencies, meant for daisy-chaining, or whether the sub is only outputting frequencies above the sub's crossover point meant to be routed to an amp for 'full-range' speaker use. My powered subs do the latter, so I could not daisy chain my subs. I use and Outlaw ICBM to run my subs in a stereo configuration, so the lack of ability to daisy chain was not an issue for me.

As you experiment, you may wish to check the response from more than one position.

Question: if are crossing to your subs at 60Hz, do you think that the suckouts at about 106Hz and 138Hz will be affected more by the placement of your mains than by your sub(s)? Depending on the roll-off above 60Hz for your sub(s), there will still be a little sub activity in the frequency range near the upper two suckouts, but I would think your mains are much more active than the sub(s) at the frequencies of those upper two dips in the graph.


[This message has been edited by bestbang4thebuck (edited August 12, 2004).]

Soundhound is insane.

So are DollarBill and bestbang4thebuck if that’s the case.

soundhound would be insane times two since he has 4 subwoofers.

I have 4 drivers as subwoofers, but those are built into the mains. I still want more. sh has 4 18" subs.

Woo Hoo! I am happy in my insanity! How about you? Happy, happy, happy, happy ...

The worst part is Soundhound is not the kind of person you would think of with 4-18" subs(not part of the Hip-Hop culture)Tubes and Hip-Hop.........OUCH!!! Now thats insane.

Lasher

save your money for 1 twice as good.

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This post has been brought to you by curegeorg, thanks for reading.

Yes, I realized later on last night that shoot, another sub isn't going to help the nulls higher than 60 Hz.

I actually did figure out that I have suitable locations at 1/2 the distance along the longest walls that might work.

My nulls might look worse than normal, because ETF is actually testing every 1.46 Hz or so. Much finer resolution than a 1/6 octave test disc for example.

One thing I will report back on: this was a 2.1 test. Both L & R and the sub firing. I need to do L & sub, then R & sub separately. Maybe I'm getting some comb filtering between the mains.

If this helps, I'm using Vandersteen's suggestion for sub and seating placement. (Even though I have Mirage's now. ) He says: start at thirds. Seating 2/3 back from the front wall, and speakers 1/3. That's too far into my room, and he goes on to say, you can also use 1/5, 1/7, etc. I'm at 1/7 for the speakers.

You're gonna have to speak up - I can't hear you above all the bass......



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The Soundhound Theater

Price alone doesn’t tell and it shouldn’t be a deciding factor. So, I’m wondering, how can a buyer figure out that subwoofer “A” is twice as good as subwoofer “B”? If I’m going for dual subs but find out that one sub of twice the quality is better than two subs of initial choice, I sure don’t want to spend all that money and end up with a sub that’s only one and a half times as good which will miss both targets (dual subs or one very good sub).

This is very risky unless there’s a clear and unbiased guideline on how to rate subwoofers.

Subs are evaluated in the same way as any other speaker. Look for the best bass extension, with the most output at that frequency, and smooth response from that point up to the crossover frequency. Be realistic too - you aren't going to get solid 20Hz response at any useful output level from a cheap subwoofer that uses an 8" driver.

The amplifiers used in subs are well matched to their drivers, so I wouldn't let the little details about amplifier class or buzzwords sway you one way or the other.

Multiple subs provide more output and because of mutual coupling between them, have a better low frequency extension than one of the subs alone, and can deal with room problems in some cases.

You could spend all the money in the world on a sub, but if you have a problem room, all that money is wasted. In a situation such as this, two lesser cost subs might be better than one super expensive one. You must evaluate your room first to see if there is the potential of strong room nodes causing problems, such if you have a perfectly square room.

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The Soundhound Theater

I use 1/12th octave 'notes'. The western musical scale, from A (27.5 Hz) to Middle C (261.63).

Those are the only tones that matter because those are the notes that play (A, A#, B, C, C#, D, D#, E, F, F#, G, G#).

I use this disc for my redirected bass sub, and a standard 1/12th octave test tone disc for the LFE sub (from 10 Hz. to 120 Hz.).

I'm +4dB/-3dB from 12 Hz up, in-room, at the LP, no PEQ used.

RB sub: 2X15, sealed, L/T, 3,200 watts. (anechoic response to 25 Hz, -3dB)

LFE sub: 2X15, sealed, L/T, 4,200 watts (anecoic response to 18 Hz, -3dB)

I run the LFE sub off the analog SW out of the player, run my 950 in 6CH BYPASS (analog BM switch to 'ON') and run the RB sub off the 950's SW out, which only contains redirected bass because the 950 doesn't have any LFE input in the first place.

I'd like to say that I still love the 950's features/sonics/price/warranty...and this forum.

I have the subs colocated, about 3.5 feet from the front right corner, against the right wall.

I arrived at this spot after many different location tries and many more minute changes around the spot they reside in now.

I also have an outboard analog low freqs tweaker preamp that I designed and had Marchand build to tweak phase settings, gain, slopes (which I arrive at by cascading filters, as the player's LFE filter and the 950's analog filter are both global) and adjustment of the 'Q'.

Sounds all big and complex, but the high power is to counter the smallish size (hate big subs), and the tweaks are really quite simple, once the initial settings for flat response are arrived at.

How's it all sound? Man...I'm in there listening every day.

KCB...keep me informed...always interested in what you're up to (like the Mirages, for example).

Soundhound is actually quite sane, (most awesome media room I know of) just a bit crusty in his old age

BoB- So "co-located" means stacked?

And, if you extrapolate the "1/12th octave 'notes'. The western musical scale, from A (27.5 Hz) to Middle C (261.63)" slightly below 20 Hz, what would the freqs be? (I'm still trying to figure out if ETF will allow me to define the freqs the test uses.)

I did try L & sub, and R & sub separately and there were some differences, but still the nulls were there. One thing I need to look at further, is increasing the 60 Hz crossover to 80 Hz. For the few tests I did last night, it *might* have looked better.

KCB,

No, side by side.

A 27.5
A# (yikes, can't read my notes)
B 30.87 (low B of a 5 string bass)
C 32.7
C# 34.63
D 36.71
D# 36.75
E 41.2 (Low E of a 4 string bass)
F 43.65
F# 46.25
G 49
G# 51.88
A 55 (next open string of a 4 string bass)
A# 58.25
B 61,74
C 65.41
C# 69.25
D 73.42 (next open string of a bass)
D# 73.5
E 82.41
F 87.31
F# 92.5
G 98 (last open string of a 4 string bass)
G# 103.75
A 110
A# 116.5
B 123.47
C 130.81
C# 138.5
D 146.83
D# 147
E 164.81
F 174.61
F# 185
G 196
G# 207.5
A 220
A# 233
B 246.94
C 261.63 (Middle C)

Boss- How about a few pts below 27.5 Hz ?

That's not necessarily the case. With the subs' crossover settings at 60 Hz, you will likely influence the the nulls upto 120 and, maybe, 180 simply due to overtones and room coupling. If you're using RTA software, it'll be helpful to find the optimal crossover point to mate the subs with your mains.

I do hope you are using pink noise and RTA software to do your measurements. Discrete tones used to test in-room frequency response are all but useless and bear very little relation to what the ear hears. Using either pink noise or warble tones is really the only valid way to do these tests.

Going down in frequency:

A 27.5
G 24.5
F 21.83
E 20.6
D 18.35
C 16.35*

*This is a 32' C pipe of a pipe organ, and none of these notes are associated with music, other than a pipe organ that's that big, so accuracy down in this realm is of no concern to me.

That's why I use the standard 1/12th octave sine wave disc for the LFE sub.

The RB, or music sub, was designed to play flat to 30 (-3dB@25, and with a second order roll off from there), which is at the actual low end of instruments, and to have extremely low group delay (5ms@30Hz) and have immense headroom for transients and to have adjustable damping (Q of .5 to 1.0) for personal taste.

I've been saying this for 2 years now, largely onto deaf ears, but summing the LFE channel with the redirected bass is the culprit in FR problems at the listening position.

When you design a sub that has to withstand the signal that all redirected bass+LFE+10 represents, you have a sub that's capable of subsonic reproduction at high levels.

Many of your favorite music discs were never monitored with subsonic capability and, therefore, include subsonic artifacts (yes, digital sources too) that a good music sub will discard, without the use of a subsonic HP filter, which causes phase shift problems that need adjustment when the filter is engaged.

A good RB+LFE+10 sub will not only reproduce those artifacts, the room it's in will grossly distort them as much as double or more. It's also almost always a ported or passive radiator design (and is BIG), and increasing order of subwoofer box design equals increasing group delay.

To those who argue that 20-30ms of time smear isn't audible down low, or if you tune a 4th or 6th order sub low enough, the group delay spike moves into the inaudible frequency range, I say..."Lay $1,000 on the table and subject me to a blind test, if I guess right every time, I get the dough."

The whole 'music vs movie' sub thing pretty much proves my theory. Contrary to lots of manufacturers claims, no one sub design does both exceptionally well. So, the answer to that is simple...have one of each kind of sub.

A smaller, sealed, high-quality sub that's flat to 25 Hz allows for it to be so much easier to reintegrate the redirected bass back into the soundfield from which it was taken, in any room, than a big, subsonic 'summed, single digital signal' subwoofer.

The LFE sub can be run hot, is silent during stereo playback, can be governed by any filter corner and slope, without affecting the RB sub and can be attenuated or even shut off when playing MC audio sources.

Otherwise, there is no tweaking required when switching back and forth from movies to music.

Keep in mind that movie discs are soon to have lossless soundtracks with much more headroom and accuracy of the signal, making multiple subs an even better idea.

Just an opinion.

SH,

Please explain why that is?

It's all about averaging.

A static tone will dwell on the peaks and dips produced by natural room modes, and the resulting measurements will read exaggerated peaks and dips in response while pink noise or warble tones do not stay on one particular frequency long enough to directly excite these modes. In other words, pink noise and warble tones average out the effects of these irregularities in response, and the resulting curve matches how the ear perceives these irregularities in response better than when discrete tones are used.

Measurements made in anachoic chambers that are used at speaker manufacturers (such as at Altec and JBL), do use discrete tones and sweeps but the difference is that an anachoic chamber does not reflect back sound from it's walls - it is essentially the same thing as doing measurements outdoors. They therefore are plotting the response of the speaker only, not the effects of the room.

This ear/measurement correlation is why we use logrithmic scales when referring to sound pressure and other audio measurements instead of linear scales. If we used a linear scale, the measured curves and how those curves are actually heard by the ear wouldn't match. A linear speaker frequency response curve for instance would look far worse than the ear would hear it.

My "Organ Demo CD" is loaded to the gills with strong 16Hz organ pedal tones. I'm very concerned with them....



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The Soundhound Theater

Thanks for the scoop on test tones, and please forgive the lapse of memory RE: the largest selling pipe organ disc in History.

I'll have to reread all of that...

I use this:

http://www.etfacoustic.com/

Just that I can tell it what freqs to use for the test signal. (See, I have this thought that if I only pick specific signals that don't encompass my nulls, I can pretend they aren't there... )

Because of the slopes, I do figure I can improve to 120 Hz with a 60 Hz crossover, but maybe up to 160 Hz with an 80 Hz setting potentially by adding another sub.

[This message has been edited by Kevin C Brown (edited August 14, 2004).]

BoB- I am intrigued by your "movie" sub vs "music" sub idea.

Right now, I have 1 Vandersteen V2W sub. Kind of meant for "movies" in that it only has an RCA input.

Vandersteen also has the 2WQ, which is kind of meant for "music", in that it has an adjustable Q, and a unique way of crossing over with the mains. Both have 3 8" drivers, but the V2W also has a 12" passive radiator.

More info here (it's a quick read):

http://www.vandersteen.com/pages/Pdffiles/2wlit.pdf

So one question is:

a) 2 V2Ws. Just send each a mono signal with a Y splitter.

b) 2 2WQs. In this case, I'd use the speaker level way of connecting them, use one for each front speaker, and then set up the pre/pro to be L & R large, no sub, and center/surrounds/rears all small. So all the bass gets rerouted to the mains with the subs.

c) A V2W and a 2WQ. I'd run the V2W with the bass from the surrounds, rears, center, and LFE and the 2WQ with the bass from the L & R. (The music sub and movie sub idea.)

Also, I know that a corner is the most recommended location. But based on standing waves and such, is there any way to say what the next best location would be?

I.e., on Harman International's web site, they suggest that 1/2 down opposite walls is a good place for two subs. (That 1/2 point is a null, so subs there would eliminate it, right?) But they actually didn't test a corner and 1/2 down a wall.

http://www.harmaninternational.com/wp/index.jsp?articleId=1003

The Vandersteen subs are kind of heavy, 80 lbs each, but I'm actually toying with the idea of getting 2 "cost effective" subs (would have to be 50 lbs or less) and just experimenting a bit. In that case, I'd actually be able to try out 3 subs. (And yes the Outlaw sub is a candidate. )

Any thoughts?

Here are 2 alinks to articles on placement that I found helpful:

here

and

here

The best setup, of course, would be 2 of the 2Wq subs in a stereo redirected bass setup and 1 of the V2W for LFE only.

If you run the analog SW out of the player for LFE only (using the player's DACs), when you switch to digital (the pre's DACs), the LFE will be inserted into the 2Wq sub or subs as well as the LFE sub, equalling a 6ish dB boost for flicks.

I forget what pre you have (MC-8 if memory isn't totally fried)??

The info you linked is a bit confusing, in that it describes the 2Wq as 'second order, slot loaded' and having adjustable 'Q' from .5 to 1.2. Hmmmmmm...second order is a sealed design, whereas slot loaded is a 4th order ported design which would make 'Q' adjustment over that much of a range difficult.

Maybe you can help me with V's terminology.

The 2WQ is sealed, and the V2W is slot loaded.

Cool, thanks for those links. Will take me a bit to digest those.

BoB- Interesting articles.

I like the first one's suggestion of the 1/3 octave pink noise and pitch method of adjusting for phase. (I have to see if I can track down those two discs.)

The HT mag article seems to contradict a lot about what I've heard for sub placement. I wish he could have included some real world measurements in terms of how the anti-node placement works vs a corner for example. And I assume that if the sub goes on an antinode, the listener goes on a node. I'm not sure about the WAF for his suggestions for placement though!

obviously true... i guess if one cant tell if one sub is better than another (2x for example), then one wouldnt notice the difference between 2 or 1... if the user is indiscrimant then the point is moot altogether.





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This post has been brought to you by curegeorg, thanks for reading.

Yes, that's why I'm curious as to people who've actually used an RTA to look at the impact of the 2nd sub. For someone to say, "I have two subs and it's much better than one" doesn't really mean much. They might just like saying "I have 2 subs".

In my case, I can say with all certainty that 2 subs are better than one, without any measurements.

Since one sub is discrete .1 and the other is discrete redirected bass, 2 subs is necessary to complete playback of any X.1 format.

Of course, with 2 channel or any .0 format, I actually only have 1 sub.

For those who have the time and aptitude for it, there is some excellent information to be found at:

http://www.harman.com/wp/index.jsp?articleId=120

One of the papers referenced at that link is:

http://www.harman.com/wp/pdf/multsubs.pdf

For those that want the conclusions first, in the room used for testing:

How many subwoofers are enough? – Four subwoofers are enough to get the best results of any configuration tried. Two subwoofers are very nearly as good and have very good low frequency support as well.

What is the optimal placement? – If cost and aesthetics are considered, subwoofers at 2 wall midpoints are preferred.

Approaching another aspect of ‘subwoofering:’

http://www.harman.com/wp/pdf/Loudspeakers&RoomsPt3.pdf

I found, by my personal mix of rudimentary objective measurement and subjective listing that:

Two subs are better than one, especially in real world, far-from-ideal listening environments. Depending on the type of music being played back, operating two subs in stereo instead of dual mono may have some benefit, and would likely have that benefit only for certain ‘live’ recordings where stereo bass was recorded in the first place and preserved through to the final playback medium.

There is no substitute for learning some basic subwoofer placement principles beyond what is found in most owner’s manuals and taking a good deal of time to experiment with subwoofer placement in your particular environment. The subs' output level must also be very carefully tweeked. There is no universal, ideal, single solution for every environment.

In my listening environment, with a convoluted arrangement of walls and spaces adjacent to the media room, I have found the following helpful:

A slightly asymmetrical placement of two subs means both subs are not exciting exactly the same nodes in the same places and helps reduce the places were bass is either boosted or suppressed by multiple standing waves affecting the same point within the listening area. (I have worked for the best listening overall in a listening area, not just a single ‘prime location.’ If using parametric EQ, this would mean using multiple sampling locations.)

A change in the position of a subwoofer by as little as three inches can produce a noticeable change in listening results.

I ‘de-couple’ the subwoofer cabinets from my ‘flexible’ flooring with some ‘cushioning.’ (Contrary to what much product ‘hype’ says, most spikes actually increase the physical coupling of a loudspeaker’s cabinet vibrations to the flooring. It’s physics.) This helps the ‘sounding board’ flooring in my situation to be more of an acoustical absorber and less of an acoustical generator.

I've experienced no problem with mixing .1 channel bass with the redirected stereo/mono bass from other channels via an Outlaw ICBM. My adjustment goal was that musical instruments with solid bass content would sound as they should - the low fundamental frequencies coming from the subs blending properly with the remainder of that instrument’s sound that come from the other loudspeakers in such a way that the original character of the instrument is faithfully reproduced. Once my painstaking pursuit of the correct music sound was as complete as I could make it, I found the reproduction of DVD movie material fell right into place without modification. I make no changes to the subwoofer setup as I switch between music and theatrical release.

Be patient, don’t be afraid to try different (non-destructive!) things.


[This message has been edited by bestbang4thebuck (edited August 24, 2004).]

>>>Yes, that's why I'm curious as to people who've actually used an RTA to look at the impact of the 2nd sub. For someone to say, "I have two subs and it's much better than one" doesn't really mean much. They might just like saying "I have 2 subs". <<<

Two or more subs excite more of the natural room modes, and at different frequencies. This causes the peaks and dips caused by these modes to be of less amplitude overall depending on placement - one sub may excite a strong "peak" while the other creates a "dip" at that frequency at the listening position, effectively reducing or eliminating the original peak.

More than one sub will equate to more efficiency (overall output by +3db over a single sub) and they will exhibit a lower extension of low frequency response than one sub alone - this is caused by mutual coupling which essentially makes two subs seem like one larger one if they are positioned relatively close to each other at the lowest frequency's wavelength. If one of your subs have a low frequency extension of 25Hz for instance, two subs could have extension to 20-22Hz or so.

These are real world and measureable benefits.

[This message has been edited by soundhound (edited August 24, 2004).]

when considering 1,2, or more subs, one must think about what they want their desired results to be. meaning that some people may need more subs (large seating area perhaps), but 2 is not better 100% of the time. if you take quality into account (quality vs price actually), then 2 is better what at what point? id say one really good sub (x dollars cost) is 90% better than two that are half as good (x total dollars cost).

you can have 1000 subs but if their low-end frequency response is 40Hz, they arent ever going to go below 40Hz. i know that is one specific example, but a valid one, as frequency response is an easily comparable number amongst subs... whereas instead of that 1000 subs, you could have 1 that goes really low.

id rather have one really awesome performing subwoofer and a small sweet spot, than some pretty good subs that blanket the room. when i am watching a movie, i dont tend to mill around, i sit in the same spot every time and watch the whole thing through (some pauses for bathroom/food, etc. of course). its silly to sacrifice quality in the attempt to get more sound, especially seeing as that more sound probably isnt going to be useable anyway.

naturally, if money was no object then you could get a bunch of awesome subs, but it usually is.

i think a lot of people get multiple subwoofers to say that they have multiple subwoofers, not really to get better sound. its their money though, so waste away.

i do not disagree that 2 subs of y quality are almost always better than 1 sub of y quality, but most people dont double their budget for subwoofers when they realize they need 2... also, sometimes 2 subs causes more noticeable nodes than 1 sub did...

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This post has been brought to you by curegeorg, thanks for reading.

curegeorg's comment:

is an odd contrast to soundhound's comment (when describing mutual coupling and the resulting effects):

Anybody care to elaborate on a point so we are all in agreement at least on our physics?

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gonk -- 950 Review | LFM-1 Review | Pre/Pro Comparison Chart | Saloon Links

The effects of mutual coupling and efficiency increases when using multiple subs can be looked and varified up in textbooks on sound reproduction, especially those that deal with professional installations that are more likely to use multiple subs. The "Handbook of Sound System Design" by John Eargle (of JBL Professional) is a good place to start.

The exact same principles apply to home installations as they do to professional ones - the same laws of physics apply.

Maybe they don't apply to some people though.

[This message has been edited by soundhound (edited August 24, 2004).]

I suppose that if the subwoofers in curegeorg’s example had wonderful output down to 40Hz, and absolutely no output at 39Hz and below, there would be no bass extension benefit. However, most subs with normal roll-off and a rated low end of 40Hz are still going to have some workable output even half an octave lower at 28Hz. The setups mentioned by soundhound seek to take advantage of those frequencies still present below an individual sub’s rated low frequency. This doesn’t mean you’ll get a interactive rating of 28Hz, but 34Hz or so wouldn’t be unrealistic in this example.

In the articles I mentioned previously, two subs provided better bass extension than four subs or more, even if four subs would provide better overall room averaging. The article(s) also point out that a two or four sub setup has advantages over a theoretical 1000 sub setup and is better than each of the five or seven loudspeakers in a multi-speaker setup all reproducing bass into the subwoofer regions. The latter is true because the best placement of subs for best bass in a room are not usually where the other speakers reside. See the articles for details.


[This message has been edited by bestbang4thebuck (edited August 24, 2004).]

A newbie looking at this thread will be out of luck if he or she wants to opt for one double quality sub instead of two lesser subs at given budget. You’ve stated what to do but not how to.

There are HT enthusiasts with limited space and would rather do away with less number of speakers if the result is certain. In this case, due to uncertainty, those people seeking better low-end performance may have to compromise on space and go with multiple subs.

Perhaps if this question could be answered: The 3db down point for the sub is where it is 3 db down from the reference level. Now if the second sub is added under ideal conditions then there should be a +3 db increase across the frequency range. This raises the reference level by 3 db. Now, why would the F3 point be different than before? Everything should be the same, just 3 db louder.

This is in an ideal model with perfect interaction. Real world setups will get much too complex for us right now.

[This message has been edited by JT Clark (edited August 24, 2004).]

To address 2 points:

If a stereo bass sub config is used with a MC format, mixing the mono .1 signal equally into both subs will collapse the stereo effect.

As was pointed out, this is in rare cases of source material, but still part of the equation, and likely moreso as MC audio evolves.

Summing the .1 channel with redirected bass can result in 'no problems' unless, like my setup, you have 1 sub that's designed for LFE and another sub that's designed for redirected bass.

If a sub is capable of very high output at very low frequencies (which it has to be to be capable of playing RB+LFE+10 anywhere near ref levels), it generally isn't as good a sub for redirected bass.

Conversely, if a sub is designed for redirected bass, it can't play the summed signal well, if at all.

If you seperate the 2 signals, like I have, each sub has less output requirement, allowing for money saved in each sub's case. Also, as I've said, generally, the redirected bass sub has a higher F3 and is designed to roll off at 12 dB/octave while the LFE sub has a lower F3 with a steeper roll off to protect it from damage.

So, it isn't a matter of having no problem summing RB and LFE into 1 or more subs (obviously it 'works', or none of us would have our sats set to 'small') as much as it affords less flexibility in sub selection and reintegration of redirected bass.

For JT’s question, not the answer one would hope for:

The beginning of the answer is that the ideal model for a +3dB across-the-board rise is an anechoic environment where two subwoofers would be co-located, but none of us lives in such a situation. Separate the subs by more than about 10% of the wavelength of a frequency in question and place these subs in real room and you’ve got the complex situation you mention where sophisticated computer modeling can’t exactly predict real world results and experimentation and measurement become the means of pursuing the best results, even for true experts. Suffice to say that the lower frequencies, say 30Hz and down, from dual subwoofers in many real world environments, will tend to reinforce each other more so than the frequencies going upward toward 80Hz, which tend to experience more of a smoothing/leveling effect when coming from multiple sources.

The middle of the answer lies in that zone you mention: too complex for us now, at least in these posts. I got my start in the mid 70’s with a book called Sound System Engineering. The current edition is 665 pages and has almost no ‘easy answers’ that would satisfy what is sought in this post. While some of what’s pictured in this book may seem outdated, the principles hold true regardless of the era from which a particular piece of equipment originated. If you have an aptitude for this kind of material, look in books or online.

The near-end of the answer, if you don’t want to spend a lot of time learning the middle, doesn’t have to be difficult if you’re willing to have a some trust in those that have studied, carefully modeled, tested, measured and evaluated aspects of at least part of the question at hand. Their answer: used properly, two of a given subwoofer is better than one (for several reasons beyond a simple +3dB gain).

This doesn’t answer questions with budget factored in, such as: which is better, two $300 subs or one $600 sub? Two $600 subs or one $1200 sub? The only way you’re going to know which will be better for you in your environment is to audition both solutions, taking the time to carefully set levels and try for the optimum placement of one sub or a pair. If that’s too difficult for one reason or another, you’re back to weighing research and opinions and taking your best guess.

Opinion time: I tried it both ways. I now have two subs, not for bragging rights but because the dual sub setup sounded and measured better once setup to my satisfaction. At the end of the day, those that have differing opinions don’t have to live with my choices, but I do.

Poll time: among those that have tried one and tried a pair, how many have stayed with two subs and who has gone back to just one? If you went back to one, was the decision primarily financial, or because you found little or no better results with two? Or for some other reason?

OK, I’m going to try and stop writing about this now. I’ve said my peace. I hope some find it helpful.

I understand about what y'all are saying about the benefits of 2 subs (or more). (That's why I'm considering it! )

But I have pinged some experts at a couple of sub companies, one of the HT mags, and other users like us, and most agree that the benefits are potentially there, just that more often than not, a 2nd sub makes things worse, i.e., comb filtering, making the peaks and valleys worse, etc. And I've even passed on that I have access to an RTA and the desire to try and make this work, but doesn't change their conclusions.

Obviously this is a hobby, and I don't mind messing around a little bit to learn something new, but ... Shoot.

One of the suggestions I got from a sub maker was... Ignore that one plot I posted earlier, but do a whole bunch more measurements around the room and for repeatability, and average them together, and *then* see how bad things are with my current setup. I did the measurements last weekend, and I'm about 25% of the way through the analysis, and although I still have dips showing up at 51 Hz and 134 Hz, the others are effectively gone.

Maybe it comes down to theory vs real setups, or how much flexibility I have to move things around in my current setup to improve things, etc. Kind of like a problem with many equations, and many variables within those equations. There's no direct solution but trial and error.

OK, so I'm not going to stop writing just yet

Yes, attempting to have the the benefits of dual subs can be 'more work, more fuss, more frustration' trying to get it right, if both subs are meant to support each other in the same role. (Segregating the duties of two subs, as bossobass has, is an approach with different potential benefits. More on that later, I hope, in a friendly exchange of ideas.)

Yes, analysis should be throughout the listening portion of a room, not just a single location, whether using something like RTA or a self-setting parametric EQ.

You won't really know what can be accomplished until you try. Certainly finding out if one sub can provide what you're looking for makes sense, as does finding out what the problems are in a room and seeking to minimize them.

KCB, your approach seems just the right path to be on: measure, learn, adjust, repeat until satisfied ... or exhausted! No one is going to find 'perfection,' just a degree of satisfaction. IMHO, your last paragraph is a great summary.


[This message has been edited by bestbang4thebuck (edited August 25, 2004).]

For some reason I have run into the mind-set that Kevin has seen - a perception that having more than one sub is more trouble than it's worth and that they have a fixation on low frequency response flatness. News flash! The low frequency response in any real world listening room is going to be frought with significant peaks and dips in response and they will be different depending on where you listen. Depending on the room, two subs can even these out or make them worse. The only way is to evaluate your room and if it has the potential to be a "problem room" - for instance if it is a perfect cube, don't even bother with one sub! If the room has more "ideal" ratios of height x width x depth and/or if it is irregular in shape, two subs can help with flattening the response.

All I can say in conclusion is that firstly, my room is more "ideal" than not - it was purpose-built to be a listening room. Secondly, each time I double the number of active subs - going from one to two and from two to four - the low end gets more subjectively "solid" (and yes, I am compensating for the volume increase with the subwoofer's amplifier). So unquestionably - in my room each doubling of the number of subs presents a very audible benefit in subjective quality - the response measures and sounds flatter and the extension of the low frequencies (playing my organ demo CD for instance) is undoubtedly improved. The lowest notes get obviously more authoritative.

right now i have 1 subwoofer for lfe. i have 2 others that i use for the lows for my fronts, but not for lfe directly. this doesnt count built-in subs that are in some of my speakers.

as with everyone it is primarily a budget reason why I have only one subwoofer for lfe, but not entirely. if i thought more was worth the money, i would have more, but i dont, so i havent wasted my money.

i have at times used more subwoofers total, and more for the lfe (while I had some on loan :-)), but came to the conclusion that i was crazy for trying to convince myself that i was making anything better.

as i have said numerous times, i would rather have one really nice sub, than any number of average ones. i dont ever strive for simply more noise or higher db, what i want is clear, articulate sound that will shake stuff off the wall if i need it to :-).

i do not think that "better" sound is achieved by two subs of lesser quality, rather than one of 2x better quality. realistically everyone has budget constraints (rather they be actual or sane limits), so if you are asking yourself, how can i get "better" bass?, the answer is not by getting more subs, instead it is by getting better a better sub, or perhaps 2 better subs.

i dont feel it necessary to argue the fine points of science or mathematics to determine what is what, i can simply hear for myself. i have heard many kinds/combination/quality of subwoofers and i could not get much better than what i have now with any amount of money that i would ever spend on home audio. value is what draws people to outlaw audio, and value is what most people consider when making a purchase. if a sub is 2x as good and 2x as expensive as another, then it is a good value. having two subs that are half as good, will never be as good as another that is 2x as good. and if you had 1000x of them, they would still not be as good as that 1 that is 2x better.

anyway, i think i have stated and restated my point enough. and before anyone quips that i have 3 subs, i only have the other two because i have bookshelf mains and dont want to loose any lowend (particularly for music), and i got to keep them (had to give the others back that i was "borrowing") for free. if i would have had to buy them, i wouldnt have, because they dont make nearly enough difference, but since i have them for free... why not utilize them...

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You have three subs.

Yep...it's three alright.

Three plus the others built into speakers.

If he hasn't crossed them over. 3 for sure though.

But the question is, are they 3 subs that are 1/3rd as good as a single normal one or three good subs that by themselves are 3 times better than a single great one instead of three mediocre ones. I guess if they were three that were 1/3rd as good, it would add up to one really good one.....but then again, if they are in stereo, or 3 channel stereo, it would still devide by three and be equal to the ratio of 3:2 which would equal....boy am I confused....

Time to stop....I just laughed beer out my nose

SH, why not eleventybillion stereo? Like in your system. Do you think threeve is a good amount for most people?

[This message has been edited by JT Clark (edited August 26, 2004).]

Like curegeorg, I also don't feel it's necessary to understand the fine points of science or mathematics to determine what is what. Objectivity is just so overrated!

All good stuff!

I have four subs.

But they're not all equal.

Two are very good. One is good. And one is ok.

Since I can't divide the goodness evenly between them, am I in trouble? Do I need to re-calibrate for the uneven distribution of goodness? I'm having trouble finding goodness correction curves in my old engineering textbooks. I guess I'm beyond help.

Jeff Mackwood

I have one 15" sub and it equals 100%! I was listening to Peter Gabriel Up (SACD) in 2 channel (I prefer the 2 channel over the multichannel in this offering) and it absolutely blows me away. In my younger days, drug enhanced listening sessions could not even compare with the aural euphoria I experienced.
But then everything is very subjective in this audio game. One man's garbage is another man's treasure.
I'm sure there are many levels of bliss in the quality of hardware and quality of recordings, but there is absolutely NO BLISS without music!!!

I get back to the club after a long time out on the boat, and what did I miss here?

You got so many subs, that you have to put them in your speakers too? You said that you only need "ONE GREAT SUB" so many times that I gave away the two subs I had on the boat. What a mistake that was... horrible mistake. And you got how many now? Did you have these all the time, or did you just learn something here? And you know, that bigger sweet spot stuff matters if you have friends.

It's hurricane season, so make sure all the subs are protected againt the storms they are predicting this year. The weather can get really ugly down in Raleigh.

[This message has been edited by Tony S (edited August 28, 2004).]

It really is alot of fun to listen/watch you guys banter about, but a few questions from someone who loves music but is a little dumb about physics/acoustical engineering/the space=time continuum.....

How do you EQ 2 subs? independently or at the same time?

How do you separate one sub for LFE for movies and one for music?

Is it more complex to have a room with four walls and ceiling and floor, or a room with a large opening? Anyone been to a huge concert hall or outdoor concert?

With subs coming down in price it is possible to get two subs for what used to be the price of one, so do you buy two of the same or do you try for two subs with different characteristics?

Sorry to keep a thread alive long after it should have been shot and buried, but these are things which I have not seen addressed yet.

Thanks for the entertainment!!

[This message has been edited by musiciseverything (edited August 28, 2004).]

Assumming you have a 950 Pre/Pro and and SACD and/or DVD-A capable player:

Set all speakers to 'large' and SW to 'yes' in the Player.

Run the analog SW output of the Player to the LFE sub.

Run the remaining 5 analog cables to the 950.

Switch the 950's analog BM to 'On'.

Run the 950's SW output to the redirected bass subwoofer.

Let the player do the decoding and set the 950 to 6 CH BYPASS.

You now have LFE only going to the LFE sub and 80 Hz and below from the sats only going to the RB sub.

Use the appropriate sub for each duty. Calibrate the RB sub's placement, phase and level, then the LFE sub.


That's 1 way to do it. There are other routing schemes.

yep, ive had one for lfe and two to compliment my mains for a few years now. i used to have 4 for lfe and 11 (one for each speaker) others. that was back when we had a seperate theatre house. things have changed since then, we've moved, i have lost a little interest in audio, etc. anyway.

my lfe sub is velodyne hgsII-18, the other two are velodyne hgsII-10 (clear acrylic housing). some of my polk speakers have built-in subs, but they are more mid-range than anything.

like i said, if i took out the two 10s, i wouldnt be losing much. how do i know, because i have tried it! just like i have tried multiple subs of equal quality spaced around, vs one that is much better.

by agreeing with other people's articles and philosophies, you can gain a moderate grasp of audio theory, but if you never try to put that theory into play, then you will never get above that moderate grasp. perhaps some people like that idea, what you dont know can make you a lot happier, cant it?



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Food for thought. Food for thought.



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The Soundhound Theater

At the risk of drawing out a thread that's already near the breaking point I am going to weigh in here.....

One benefit of the using multiple subs that I don't think has been mentioned here is that by doubling or quadrupling the number of drivers, the excursion required to reproduced a given frequency and SPL, the excursion of each is greatly reduced. This reduces several types of distortion, and is the basic principle behind line arrays. If the burden of generating absolute SPL is reduced for individual drivers, the fidelity will be increased. This is one reason quality headphones are so accurate. So in this way at least, two or more cheaper drivers can produce a qualitative and not just quantitative improvement.

more drivers does not equal lower frequency... is that what you were trying to say, along with more spl? i hope not. more spl does not equal quality either...

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1. If all channels are set to large, will there be any output from the .1 channel? 2. Is the .1 channel discrete or is it derived bass from the other channels? 3. Is the center channel full frequency response or is the bass limited like some processors from the past?
Thanks, Reed

Reed - I assume that these questions relate to the Model 950 and its bass management.

1. When all channels are set to large, the only data that should be sent to a subwoofer is the .1 channel of a Dolby Digital 5.1 or DTS soundtrack. No bass from the other channels would be re-directed to the subwoofer.

2. Technically, one could argue that the .1 channel refers only to the LFE channel contained in Dolby Digital and DTS soundtracks, which is not derived from the other channels. The subwoofer output from the 950 (and any similar processor) will include the .1 channel and any redirected bass that might exist (depending on the bass management settings that have been selected).

3. The 950's center channel is full range when set to "large" and is not bass limited. This should be the case for all Dolby Digital and DTS processors, as both surround formats include full range channels for center and surround, as well as Dolby Pro Logic II. On the other hand, it was not true of Dolby Pro Logic; the matrixed center and surround channels that Pro Logic used were frequency limited (although I forget what the exact upper and lower limits were).

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gonk -- 950 Review | LFM-1 Review | Pre/Pro Comparison Chart | Saloon Links

Thanks Gonk. Your answers to my 3 questions is how that I thought it worked. I plan on using 3 electronic crossovers to add a subwoofer to each of my 3 front channels and will set them to large. I will also add a 4th subwoofer for the .1 channel to reproduce that information. My surround channels will be set to small and that information should go to the .1 channel. I now have to build the room for all of this stuff.

Just to check, are you setting the 950's signal to large, send the signal to the crossover which then splits it appropriately to the sub and speaker?

Yes, that is the way I will be setting my 950. I will be setting each of the 3 front channels to large, then go to 3 separate electronic crossovers, then to 6 amplifiers. Three to the regular front channels and 3 to the subwoofers. There will also be the 7th amplifier for the .1 channel subwoofer. My surround will be set to small as they are not full range. Their bass should go to the .1 subwoofer and be added to the regular .1 information. I will be using the M-200 for all of my channels including surrounds. I am still in the process of building the room so it is not set up yet.

Perhaps all that needs to be said has been said, but I’m still typing

There has been no absolute standard by which subwoofers are judged that could result in a universally recognized performance/value ‘points system’ where one could say, “I compared two subs (1.3 rated) with one sub (2.6 rated) and found that I prefer such-and-such.” So when one can’t answer the question of which sub is twice as good as another, one can’t really even arrive at the question, “Which is better, one ‘twice-as-good’ sub or two ‘good’ subs?” I guess the question comes to, “Which do I prefer, two, three or four of the best $1X dollar subs I can find, or one of the best $2X, $3X or $4X dollar subs I can find?” Because the particular listening environment you have plays such a large part in finding that answer, the only real way to find out is find the time to give each a proper setup and listening test in your environment.

I recently had the chance to compare the use of two Sony WX-700’s (about $250 each) with two Sunfire Signature’s (about $1150 each). These subs were built with similar design goals – two moving surfaces, small footprint. The WX-700’s have a slightly larger footprint while the Sunfire Signatures have slightly larger drivers. Because the Sunfire’s drivers are more exposed, each Sunfire needed slightly more clearance than the Sony’s, so each type needed just much floor space as the other. I would have liked to have included two LFM-1’s in the comparison, as their performance at their price point is very, very good, but the LFM-1’s were not as easily obtained and returned.

Quick Q&A’s:

1: What were the notable differences? The Sunfires offered more output and lower frequency extension, but two WX-700’s still offered plenty of ‘authority.’

2: Was the Sunfire “four times” better than the Sony? Nope.

3: If a budget had room for them, would I spend the extra $$ for the Sunfires? Yes. As is usually the case, as one approaches diminishing returns, a ‘50%’ improvement may cost four times as much.

4: On a tight budget, how would I spend? I’d buy two of the WX-700’s for now. One to four years from now, I would expect I could upgrade – I would have time to save and I expect that the price performance of subs will continue to improve, so perhaps a sub with better performance than the WX-700 will be available later on for less than the Sunfire Signature costs now. And the WX-700’s would still sound great in a second system.

Again, I wish I could have had the LFM-1 in the comparison. Perhaps it is that value, sought in the last paragraph, available now, between the WX-700 and the Sunfire model compared. The LFM-1 is about twice the cost of the WX-700 but about half the cost of the Sunfire Signature.


bossobass: In the setup mentioned in the post of August 28, how would you control the playback volume? If you are using the 950, then the LFE subwoofer level would remain unchanged while everything else, going through the 950, would be variable.

at least subwoofers (speakers really) arent becoming redefined as quickly as other gear... they can last you quite a long time, perhaps indefinitely.

i would have to agree with your statement about 4x as much money for 50% improvement in general, but that is why one must be selective when searching for his answer. there are good values out there, you just have to look or get lucky.



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BB4B,

Good question.

I use an outboard low frequency processor that has a seperate channel for each sub, including a preamp section with gain, thatI use to level the volumes. I leave the 950's SW trim and the player's SW level at a reference level and season to taste from there using the LF pre/pro gain controls.

The 950's master volume keepsthe RB sub fairly leveled with the satellites.

I say 'fairly leveled', because when the volume is lowered for the system to below a certain point, the Fletcher Munsen hearing curve makes it sound as though the low frequencies are not calibrated anyway.

I've found that the .1, or LFE sub needs no leveling in the case of DVD-A/SACD multichannel tunes because they mostly contain low levels of signal in that channel.

In fact, I find that, in that case, if I lower the rest of the system, volume-wise, the LFE sub's volume staying the same fills out the Fletcher Munsen curve perfectly.

On DVD playback, I simply don't listen at all over the map levels. The roughly 3 different levels I use, for whatever reason, are easily and quickly adjusted to as to what level the LFE sub should be for each setting, and I adjust the LFE pre/pro gain accordingly before starting the disc.

This can just as easily be done using the LFE sub's amp gain, or the SW trim in the player's menu.

If I watch a flick late at night and don't want to disturb anyone (in which case, it's never a bass-heavy action flick), I simply mute the LFE sub altogether (as well as bump up the center channel trim 3 dB for dialog).

Why, oh why can't the pre/pro designers just add a discrete LFE output jack and a toggle to sum the outputs (RB and LFE) ALA the Lex MC-12??

Some recent trivia:

I've recently worked with 1 design team of a new pre/pro regarding this very thing and the related bass management particulars.

I've also begun some interesting modulation distortion tests based on the idea that this set up (of discrete RB and discrete LFE subs vs the single, summed signal to whatever number of subs) results in huge improvement in reducing this kind of distortion during playback of MC audio.

BoB- The Fletcher-Munson info begins to screw with a person's beliefs when you start to realize that the overall volume has to be a significant value before the sub-20 Hz content even registers...