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#396253 - 08/21/13 09:03 AM How many Subs are enough ??
TroyD Offline
local

Registered: 02/17/04
Posts: 295
Ok I found a very interesting, White Paper Study done from,
The Science of Audio ...This is the conclusion after many pages and graphs of reading

One subwoofer at each wall midpoint is the best in terms of
Std, Max-ave and Max-min but does not support low
frequencies particularly well. Two subwoofers, at opposing
wall midpoints, performs very nearly as well as four at the
midpoints and gives a much better LF factor. One
subwoofer in each corner also has good low frequency
support, but does not perform quite as well as one
subwoofer at each wall midpoint, in terms of Std, Max-ave
and Max-min. If cost and aesthetics are considered,
subwoofers at 2 wall midpoints is preferred.
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#396255 - 08/21/13 09:47 AM Re: How many Subs are enough ?? [Re: TroyD]
nickbuol Offline
connoisseur

Registered: 09/16/04
Posts: 4449
Loc: Marion, IA
I've never heard it anywhere that a 4 sub setup somehow loses low frequencies. Not saying that you are wrong, but can you share your source?

I do know that some people complain that "I moved my sub out of my corner and put it on the middle of one of my walls right next to my seats, and there is less bass." Of course, there are lots of issues with that example. Corners make the bass seems louder and boomier, the sub placement impacts peaks (and nulls), so on and so forth.

Increasing from 1 sub to anything more than 1 sub helps to even out the whole low end frequency response. Maybe there are other factors playing into your example of 4 subs along the 4 wall mid-points (which to many experts is considered to be optimal for low frequency response) where low end is lost. Maybe it is just that enough of the nasty peaks (and nulls) have been lost that you are hearing less bass at certain frequencies and perceiving it as bad, when in fact it is just putting the bass at levels that they are supposed to be at?

Again, your source info would be great.

Oh, and I am by no means saying that you are wrong, just that this portion with 4 subs conflicts with what the general consensus among experts say.

Now, I will agree with you for sure that the difference in going from one sub, to 2 subs (even if not put into the ideal locations at the mid-points of opposite walls) yields the best "bang for your subwoofer buck" in taming the peaks and nulls and going beyond 2 definitely yields diminished returns for the price. It certainly does get better, but costs twice as much to get the last "20%" so to speak.

Here is a link to a YouTube video with Ian Colquhoun...

Multiple Subs
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#396256 - 08/21/13 10:39 AM Re: How many Subs are enough ?? [Re: TroyD]
dakkon Offline
connoisseur

Registered: 02/08/04
Posts: 1846
Ian published this video. i don't think any of his graphs showed a drop off in the low end.?

http://youtu.be/ayOXz26qm3I

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#396263 - 08/21/13 03:07 PM Re: How many Subs are enough ?? [Re: TroyD]
nickbuol Offline
connoisseur

Registered: 09/16/04
Posts: 4449
Loc: Marion, IA
Isn't that the same video I posted? Why yes, yes it is. grin
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#396269 - 08/21/13 04:15 PM Re: How many Subs are enough ?? [Re: TroyD]
Boltron Offline
veteran

Registered: 11/18/11
Posts: 171
Loc: Toronto
I don't think I can ever have enough subs wink Wife doesn't see it that way unfortunately.
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#396270 - 08/21/13 04:33 PM Re: How many Subs are enough ?? [Re: TroyD]
tomtuttle Offline
axiomite

Registered: 06/20/03
Posts: 8283
Loc: Tacoma
I like Ian. He's a cool guy.
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#396271 - 08/21/13 04:38 PM Re: How many Subs are enough ?? [Re: nickbuol]
Nick B Offline
devotee

Registered: 08/05/06
Posts: 495
"One subwoofer at each wall midpoint is the best in terms of Std, Max-ave and Max-min but does not support low frequencies particularly well. Two subwoofers, at opposing wall midpoints, performs very nearly as well as four at the midpoints and gives a much better LF factor. One subwoofer in each corner also has good low frequency support, but does not perform quite as well as one subwoofer at each wall midpoint, in terms of Std, Max-ave and Max-min. If cost and aesthetics are considered, subwoofers at 2 wall midpoints is preferred."

The above is an excerpt from the conclusion of a presentation by Harmon I found online, which is based on a very nice Matlab simulation run in a rectangular room. Link: http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/multsubs.pdf
I think that this is either the paper that the original poster is referring to or what they are basing their statement on.


Again, all of what is being said depends on having a sealed rectangular room with good dimensions, ie one wall dimension not a multiple of the other, etc. What I got out of reading the above is that it comes down to either 2 or 4 being the "best". By "best" they mean minimizing the seat to seat variation, for a number of seats, being the biggest factor. The next factor of importance being increasing output as the number of subs increases and the third being cost. If you are going to use 4, then it is best to put each one in a separate corner in the room. This will give you more output than having one or two. Having 4 subs at the midpoints of each wall will have less output than just having one subwoofer, which is not a good use of all of the added expense, though the seat to seat variation is a slight bit better. With 2 subwoofers at the midpoints of opposing walls you get nearly the same seat to seat variation, with half the cost, but slightly less output compared to 4 subs in separate corners. In the link above we see that Harmon ran simulations with two subs in both midpoint of opposite wall positions as well as 1/4 distance from the corner on same wall and the midpoint position was better with seat to seat variation. Though I saw a review of 2 Powersound XS30s (very nice looking subs by the way, which I would love to have in the future if I can fit in the budget), where the 1/4 distance along the same wall had slightly better seat to seat variation in a room of different size dimensions than Harmon used in the simulations. Link: http://www.hometheatershack.com/forums/h...mpressions.html

To sum up, 2 subs seems to be basically the best in terms of value, seat to seat variation and additional output compared to using one sub. Having 4 subs may produce either additional output or better seat to seat variation, but maybe not both. Hopefully the room that the subs would go into would be a rectangular and sealed, then the best position will either be the midpoint of two opposing walls or 1/4 distance along one wall.

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#396272 - 08/21/13 05:19 PM Re: How many Subs are enough ?? [Re: TroyD]
nickbuol Offline
connoisseur

Registered: 09/16/04
Posts: 4449
Loc: Marion, IA
Interesting. So much in there that seems to go hand-in-hand with other resources, and a bunch that doesn't. Typical corner placement creates exagerated (boomy) bass. Of course their test room was an almost bare 20'x24'x9' which isn't acoustically great. They tested directly in the center of the room, which is "less-than-ideal" as nulls are easily occuring there, so on and so forth.

So what does that mean? Heck, I don't know. Too many variables and how it does or does not simulate what you have in your house for room size, relationship of seating (exact center of the room for example), what is in your room impacting acoustics, etc.

I guess I look at this somewhat "real world test" is that someone could do the exact same test in a different room and get different results. That is why these kinds of tests should be done in such a fashion that tried to eliminate the specific room impact. Much like how Axiom uses an anechoic chamber to measure the speaker and only the speaker without coloration of the listening space. Again, if all real-world listening spaces were the same, then cool, but since they aren't then I say that the test is somewhat flawed. Good information for the most part, but still not a perfect test. I guess it is the perfect test if that room happens to be YOUR room...
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#396279 - 08/21/13 10:37 PM Re: How many Subs are enough ?? [Re: nickbuol]
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10386
Nick, Troy is apparently(as Nick B suggests)using the Harman study as the source. What's being misinterpreted in some of the comments here is the "LF factor". This doesn't mean that the total low frequency energy goes down when more subs are in operation. The total actually increases, but a correction factor to "normalize" for the number of subs is applied to get the LF factor. This measures the efficiency of adding more subs in a particular configuration. In other words, each added sub doesn't increase the total low frequency output as much as would be thought simply by looking at the increase in numbers of subs.
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#396281 - 08/21/13 11:03 PM Re: How many Subs are enough ?? [Re: TroyD]
TroyD Offline
local

Registered: 02/17/04
Posts: 295
The Science of Audio

yes Nick it is what I was talking about wink
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