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Are more subwoofers always better?

3K views 48 replies 18 participants last post by  Bill Fitzmaurice 
#1 ·
Is this true? Are more subwoofers always better or are fewer subwoofers sometimes better for specific rooms (not talking about appearance/aesthetics but only performance). Basically, can you get a worse frequency response but adding more subwoofers?
 
#3 ·
Thanks.

I was wondering because I've read that someone actually got better bass (better frequency response and/or better sound quality) by using 2 subwoofers instead of 4 in the room. I just wanted to know how that could be possible.
 
#4 ·
I only have one sub. Well, one sub each in two different rooms. Both are great, thank you, and doing their jobs. The more subwoofers you add, the more you can smooth troublesome room modes and the more output one can attain. It comes at a price, and that price is integration and how a second sub will react in your room and to the other sub. Now, could I have better bass with more than one sub in each room? Perhaps, but I only need to fill one seat in each room, and since I'm a simple man, I like things simple :).
 
#5 ·
Typically yes. But, the room itself can is a huge factor. There was someone one this board who couldn't get 2 Rythmiks to work well in his room. However, I would say that's the exception, not the rule. I use to have two SVS 20-39s in my room and they worked a lot better than just one. Much smoother. Now, with my THT I don't feel that 2 would be necessary, as I find locating the sub impossible and no matter where I sit it sounds awesome. That being said, I'll be building another next spring and stacking it on the other one, basically I want more spl, and unfortunately in my room I don't have another corner to put another one in; when I first placed it I had it right behind the MLP, which was a great ride but it sounded really boomy and inaccurate. Once I stuck it in the corner, so much smoother and accurate.

So yes, two can be better than one, three better than two and on and on. But again, depends on your room, what you're looking for and how much you want to spend.
 
#11 ·
If you co-locate the subs they might not help the room response, just play a little louder. If you put multiple subs in the wrong places they can hurt the frequency response. Done properly, multiple subs should always help, but like Bill and everybody said there is a point of diminishing returns.

IMO - Don
 
#14 ·
Without any qualifications to the question, the answer is flat out NO, as the result depends on the room and where the subs & listeners are located.

Once you qualify the locations, the listening area of interest, and if measurements have been taken to confirm things. Start here in the recent thread about thebland's room & subwoofer setup. If you simply turned on the front/rear subs and listened to the response in RED, you would come to the conclusion that more subs are worse:


Digging further through the thread, if you only had one row of seats in the room, 1-4 subs all placed at the front wall in this room could give you something similar to this (no EQ here, where GREEN shows the back row for comparison):


One vs. 2 vs. 3 rows in a room greatly increase the difficulty in achieving uniform response, and greatly increases the likelihood that multiple subs *can* provide a better result... If they are placed and integrated in useful locations.
 
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#24 ·
Mark, what if the thread topic read, "Can one have too many subwoofers?"

Let's say "in theory" one built a room with all vertical walls housing nothing but arrays of subs. Let's go one step further and say that literally almost any space not used for a speaker, was housing a sub.

With all of that surface area being subs with radiating cones, would their be a necessity for room treatments/bass traps?

I guess the answer is a bit more complicated than yes or no, but with the proper DSP do you think it could be done?
 
#16 ·
I won't get into the fray here because, while I have 4 subwoofers, every one is in a different room. My only comment is that, in the audio business you have to add perspective to what every one says. What one person calls a sonic epiphany, someone else might describe as a subtle difference.

My home theater is pretty modest and sports only a single 15" sub. But the sub is powerful enough to shake the walls and the seat of the pants. It fills the room without hinting of its location and sounds great. In other words it is satisfying. Would another one be better or would 3 more be better still? Maybe. The graphs certainly show smoothing of room modes. Is that important? Maybe. It isn't important to me because my sub is already satisfying. I've measured my sub and I know it has a significant peak at 30hz and it starts dying at 25 hz. Is that important? Perhaps but not to me. The sub is quite satisfactory to me. I don't know what adding a matching sub would do in my home theater because I haven't tried it. Why? Because what I have is satisfactory and my guess is that adding one would be something less than an epiphany. It might provide a better graph but I doubt that it would change my life meaningfully. Why spend money to fix what isn't broken?

Subwoofers have become a hobby. You can read about some of the more over the top installations in this very forum. For me subwoofers are not a hobby. They are a way of reproducing low frequencies better than my speakers can by themselves. So try to put some perspective into what you read in the forum. You may be somebody who is obsessive about bass or you may be someone like me who merely appreciates what a good sub can add to an audio system. Your own approach to audio may have more to do with how many subs you should buy than the feelings of others.
 
#18 ·
Ok, good to know. Thanks Bill. Still not sure if it would just be easier just to build another THT, seeing as I've already built one. Which, by the way, it rocks.
 
#19 ·
When I had one, the front right corner was the best. I got a second one and would of liked to of placed it in the rear left corner, but room layout prohibited this. 1/3 from the front wall on the left side works well. It also worked well with the wife.
 
#29 ·
This should clear things up, for those whom are reasonable and seeking truth:

"Colocate as Don50 used it; simply means to place two or more items, persons, machines, etc., in the same location, or proximity, as practically permitted." - my original statement, context preserved...

Now, Thomas Mundorf who solved a major issue for Metallica, whom was desiring a circle center stage and to be able to create an array with even output in every direction, including energy below 100Hz which cannot be model in software.

Listen to Big Nicks initial statements about how Tom got the sub arrays to mutually couple; he colocated them ;-)!

Meyer, Midas, Metallica - it doesn't get any better until you colacate, and fly a 40 or so subs above the stage.




 
#31 ·
LOL - no he didn't... the math was first outlined in a practical manner by Tesla. Thomas back in and around 1993-4 was the first to apply it, as you just viewed. It is common practice now, when application calls for it.;) - truly a funny statement!

Reminds me of the old Nike commercials - Boo Knows - but instead it's Earl Knows...
 
#32 ·
Would 4 subwoofers be too many in this room? I needed speaker stands for my main speakers (thinking about Seaton Sound Catalyst 8C all around for the 5 channels) so I thought I might as well get 4 subwoofers and place the Catalyst 8C speakers on them (the center Catalyst 8C will be on a stand). The subwoofers would be 2 SubMersive HPi+ with 2 slaves.

Would getting 2 SubMersives placed up front under the front left/right Catalyst 8C speakers with stands for the surrounds be better?

Here is a quick/very rough drawing of my room.

 
#33 ·
Would 4 subwoofers be too many in this room?
Impossible to say. I'd get two to start, place one in the front of the room, one in the back, take the required measurements, apply the necessary EQ. If they do the job you have enough subs. If they don't get one or two more.
 
#34 ·
Your room has almost the same dimensions, leading to doubling of room modes. You might find placing the subs asymmetrically, or in pairs at odd points along the wall (e.g. front and 1/3 or 2/3 points) may provide better room response. Best is to try and see, preferably using measurements.
 
#35 ·
The room is almost the same dimension L x W, potentially leading to doubling of room modes. Placing the subs at the front wall and 1/3 or 2/3 points may lead to better response. You could do it in pairs, but that's a fairly small room for four subs. I would personally try two first.
 
#39 ·
Thank Mark. I did read the other post and that helped clear up a couple of questions. I have 4 sub and calibrate them in a similar fashion, front 2 and rear 2 with delays. I have nowhere near as sophisticated calibration gear but, it get a decent result. I do see how there is room for improvement with better gear.:)
 
#46 ·
This seems like a decent place to ask this question regarding mutual coupling. Since it's seemingly accepted that two subs are mutually coupled when they are less than a 1/4-wavelength apart, that implies that for a given separation distance, they are mutually coupled below some threshold frequency, and "distinct" (i'll use that as my term for not mutually coupled) above that same frequency. Being a geeky engineer, i plotted it (see attached graph).



My question is, should you strive to have that threshold outside the normal operating range of the sub? Or in other words, if that threshold falls right in the 20 - 60 hz range, does it create problems? If you want to have them mutually coupled all the way to 80 hz, you'd have to have them
 
#47 · (Edited)
Keep in mind the purpose of mutual coupling, which is to have two or more subs essentially act as one, with their outputs fully constructively summed. There are circumstances where that's useful, mainly in pro-sound applications, where response throughout most of the listening area is mainly determined by the speakers, not the room. In that case mutual coupling usually works best, by preventing power alley effects.
http://www.prosoundweb.com/article/in_search_of_the_power_alley/

In homes room modes and boundary interactions are just as responsible for response at the LP as the speakers themselves. Mutually coupling subs in that case won't improve response, as all of the subs in the stack will excite the same room modes, and suffer from the same boundary interactions. Splitting them has each exciting different room modes and different boundary effects, which will usually give a better result than mutual coupling.

As to your math, if the subs are, for instance, 3.5 feet apart, they'll couple at all frequencies below 80Hz. If you had them 9 feet apart they'd couple at all frequencies below 32Hz. That's not to say that they don't couple at all above the 1/4 wavelength frequency, they do, but with response dips based not only on their distance apart but also the listener's position relative to them.
 
#48 ·
Ok, thanks for that. So if you have room mode issues causing dips in the FR at the MLP at say 40 or 50 hz, then having dual subs placed
 
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