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Multiple Subs and the Law of Diminishing Returns

post #1 of 17
Thread Starter 
So, I've ended up with 4 PSA XS15s in my relatively large living room (4880 cu. ft.) and I've noticed through this process the following that relates to the law of diminishing returns:

2 subs = 75% better than 1 sub*
3 subs = 25% better than 2 subs*
4 subs = 10% better than 3 subs*

(* in terms of perceived sound quality and using identical subs)

I recently went from 2 subs to 4 subs, and while I didn't really expect 4 to be "twice as good" as 2, I was kind of surprised that it wasn't more of an improvement than it was.

As in all things audio, you can reach the point of diminishing returns rather quickly no matter how much money you throw at it! smile.gif

I just wanted to post my observations so that new people won't expect miracles when it comes to multiple subwoofers...yes, they help and more is always better. Just keep in mind that "better" is a relative term.
post #2 of 17
I have experience from going from a single, to duals, to quads, and now a 3 sub configuration.

What I found is that I got great response with only 2 subs at the main listening position, but I needed 3 or more subs to get good response over multiple seating positions and couches.

So really little to no improvement going from 2 subs to 4 at the MLP, but a big improvement over multiple positions.

As you know there are a few guys around here that have proven 16 sub systems are as epic as they sound, so maybe law of diminishing returns doesn't apply to all wink.gif
Edited by Spanglo - 11/6/13 at 9:03am
post #3 of 17
I thought your reason for adding more subs was to smooth the response? I went from 2-3 XV15's to offer a better response across multiple seats. I was suprised to see that I gained another 4db at the LP. For my room 4 is not going to be very cost effective . Perhaps you should of contacted Tom before pulling the trigger. smile.gif
post #4 of 17
The benefit of multiple subs is mainly for the room response and not to increasing spl or extension. You may get more spl and extension but, if the system is calibrated not much difference. I read somewhere 2 subs will get you 75-80% for a good room response. Three will put you near 90% and four subs will put you close to 100% in terms of a good room response. No real benefit to go beyond 4 subs.
post #5 of 17

Very interesting stuff here. I have dual subs and have been wondering (but not actually considering doing it) what three and four subs would do. Great information. Thanks.

post #6 of 17
Quote:
Originally Posted by Alan P View Post

So, I've ended up with 4 PSA XS15s in my relatively large living room (4880 cu. ft.) and I've noticed through this process the following that relates to the law of diminishing returns:

2 subs = 75% better than 1 sub*
3 subs = 25% better than 2 subs*
4 subs = 10% better than 3 subs*

(* in terms of perceived sound quality and using identical subs)

I recently went from 2 subs to 4 subs, and while I didn't really expect 4 to be "twice as good" as 2, I was kind of surprised that it wasn't more of an improvement than it was.

As in all things audio, you can reach the point of diminishing returns rather quickly no matter how much money you throw at it! smile.gif

I just wanted to post my observations so that new people won't expect miracles when it comes to multiple subwoofers...yes, they help and more is always better. Just keep in mind that "better" is a relative term.


From 2 subs to 4 subs if co-located is quite step up in tearms of increase SPL, and that is +6 dB which you can hear loud and clear, so it is step up smile.gif
post #7 of 17
Don't forget that if you have a calibrated system then each sub will be working less hard to reach the desired volume level, assuming a multi-sub setup, which should reduce distortion and improve sound quality smile.gif
post #8 of 17
Thread Starter 
Quote:
Originally Posted by basshead81 View Post

I thought your reason for adding more subs was to smooth the response? I went from 2-3 XV15's to offer a better response across multiple seats. I was suprised to see that I gained another 4db at the LP. For my room 4 is not going to be very cost effective . Perhaps you should of contacted Tom before pulling the trigger. smile.gif

And it did smooth the response a lot, especially away from the MLP. Don't get me wrong, I do not regret the purchase in the least! smile.gif

Quote:
Originally Posted by derrickdj1 View Post

The benefit of multiple subs is mainly for the room response and not to increasing spl or extension. You may get more spl and extension but, if the system is calibrated not much difference. I read somewhere 2 subs will get you 75-80% for a good room response. Three will put you near 90% and four subs will put you close to 100% in terms of a good room response. No real benefit to go beyond 4 subs.

Quote:
Originally Posted by ZivkoF View Post

From 2 subs to 4 subs if co-located is quite step up in tearms of increase SPL, and that is +6 dB which you can hear loud and clear, so it is step up smile.gif

Quote:
Originally Posted by MemX View Post

Don't forget that if you have a calibrated system then each sub will be working less hard to reach the desired volume level, assuming a multi-sub setup, which should reduce distortion and improve sound quality smile.gif

Agreed. Allt I'm trying to say is the overall sound quality improves at a smaller and smaller rate as you add more subs to the equation....is it worth it? To me, that's a big fat YES! To others with maybe less disposable income....maybe not.
post #9 of 17
My mistake Alan, I thought you were disapointed going off of your initial post.
post #10 of 17
One of the nice things about getting more consistency is that EQ'ing the MLP makes the other seats better instead of worse. On the other hand, my wife might be happier sitting in a null.
post #11 of 17
Thread Starter 
Quote:
Originally Posted by rcohen View Post

One of the nice things about getting more consistency is that EQ'ing the MLP makes the other seats better instead of worse. On the other hand, my wife might be happier sitting in a null.

Ain't that the truth. biggrin.gif
post #12 of 17
Quote:
Originally Posted by Alan P View Post

So, I've ended up with 4 PSA XS15s in my relatively large living room (4880 cu. ft.) and I've noticed through this process the following that relates to the law of diminishing returns:

2 subs = 75% better than 1 sub*
3 subs = 25% better than 2 subs*
4 subs = 10% better than 3 subs*

(* in terms of perceived sound quality and using identical subs)

I recently went from 2 subs to 4 subs, and while I didn't really expect 4 to be "twice as good" as 2, I was kind of surprised that it wasn't more of an improvement than it was.

As in all things audio, you can reach the point of diminishing returns rather quickly no matter how much money you throw at it! smile.gif

I just wanted to post my observations so that new people won't expect miracles when it comes to multiple subwoofers...yes, they help and more is always better. Just keep in mind that "better" is a relative term.

So, doing the math...

2 subs = 175% better than 1 sub

3 subs = 219% better than 1 sub

4 subs = 241% better than 1 sub

Still seems like pretty good gains to me!!!!! biggrin.gif
post #13 of 17
Quote:
Originally Posted by willscary View Post

So, doing the math...

2 subs = 175% better than 1 sub

3 subs = 219% better than 1 sub

4 subs = 241% better than 1 sub

Still seems like pretty good gains to me!!!!! biggrin.gif

I think it's

2 subs = 75% better than 1
3 subs = 119% better than 1 ((1.75 x 1.25) -1)*100%
4 subs = 141% better than 1 ((1.75 x 1.25x 1.1) -1)*100%
post #14 of 17
Thread Starter 
Hey! Don't bring math into this!! tongue.gif
post #15 of 17
Quote:
Originally Posted by Alan P View Post

2 subs = 75% better than 1 sub*
3 subs = 25% better than 2 subs*
4 subs = 10% better than 3 subs*
Perhaps, subjectively speaking. From an engineering standpoint if you consider two subs to be twice as good as one then the progression is that it takes four to be twice as good as two, eight to be twice as good as four, sixteen to be twice as good as eight, and so on. Getting increasingly worthwhile results isn't so much a matter of diminishing returns as it is diminishing funds.
post #16 of 17
Quote:
Originally Posted by Bill Fitzmaurice View Post


Perhaps, subjectively speaking. From an engineering standpoint if you consider two subs to be twice as good as one then the progression is that it takes four to be twice as good as two, eight to be twice as good as four, sixteen to be twice as good as eight, and so on. Getting increasingly worthwhile results isn't so much a matter of diminishing returns as it is diminishing funds.

So very true. My funds run out long before my desire for new and better.

post #17 of 17
Quote:
Originally Posted by KidHorn View Post

I think it's

2 subs = 75% better than 1
3 subs = 119% better than 1 ((1.75 x 1.25) -1)*100%
4 subs = 141% better than 1 ((1.75 x 1.25x 1.1) -1)*100%

Yup...I should not have used the word "better" with my totals. Had I just said 219% of 1 sub, it would have been correct. The word "better" implies a starting point at one sub while the percentages I used were from a baseline of zero. One sub is already 100% so 119% better than 100% is correct. smile.gif
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