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Multiple shallow subs

HooStat

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#1
Based on a recent thread on inexpensive subs, I was looking at the Monoprice slim sub (there is a 10" and a 12"). Link here: https://www.monoprice.com/product?p_id=35847

According to Brent Butterworth's spreadsheet (https://docs.google.com/spreadsheets/d/1KjlXBWMPAHgU_V9DAHSdIZ_ke0MxwH6ekt3vTIlYOJU/edit#gid=0) it has decent performance for the $150- $200 price.

I have an entertainment center on which my TV sits. This is 100" wide and 26" tall, and it sits almost 10" into the room. Given this, I could fit 3-4 of these behind it. I am just wondering if anyone has thoughts on how this might work. My perception of the benefit is that it is inexpensive and would presumably provide plenty of volume (i.e., 3 would provide 4.7 db more than the single sub). We don't actually listen that loudly, so that is not the concern as much as having the headroom when needed, and having the subs out of sight. Given that 3 of these costs the same as most inexpensive single 12" subs (e.g., SVS, Rythmik, etc) it seemed like an interesting solution.

I could add a more traditional sub elsewhere in the room to smooth things out.

Also, maybe there are other subs that are about 10" wide (say, stacked 8" drivers) that I don't know about. If there are, I would appreciate learning about those too.

I would appreciate any other thoughts people have. I imagine that trying to EQ this might become challenging, for example.

EDIT: I said 20dB more but it is more like 10log(3) more which is 4.8dB. Though someone said 9dB below. Either way, my error. Forgot that dB are on the log scale and not additive.
 
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Willem

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#2
Multiple subs improve the sound quality but only if you put them in different locations. So by all means have one of these slim ones behind the screen, but preferably locate the three others elsewhere.
 

sigbergaudio

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#3
Not sure how you are calculating this, but three subwoofers will NOT give you 20dB more volume than a single sub. It will give you at most 9dB more, depending on the frequency. Typically at the very low end. Higher up in the frequency range you will not get a lot more, since it's the bottom end that is limiting the subs.

Also note that if I understand the Butterworth sheet correctly it's 1m peak, so the numbers are actually 9dB higher than the comparable number in the data-bass.com database (which is 2m RMS).
 

Unclevanya

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#4
Aren't those particular subs designed for use flat on the floor? I thought the intent was to put one under the couch not vertical behind furniture.
 
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#5
Also note that if I understand the Butterworth sheet correctly it's 1m peak, so the numbers are actually 9dB higher than the comparable number in the data-bass.com database (which is 2m RMS).
Wait really? I didn't catch that before. Wow, that makes the SVS SB-12NSD that I've been eyeing even more of a steal.
 
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HooStat

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Thread Starter #6
Not sure how you are calculating this, but three subwoofers will NOT give you 20dB more volume than a single sub. It will give you at most 9dB more, depending on the frequency. Typically at the very low end. Higher up in the frequency range you will not get a lot more, since it's the bottom end that is limiting the subs.

Also note that if I understand the Butterworth sheet correctly it's 1m peak, so the numbers are actually 9dB higher than the comparable number in the data-bass.com database (which is 2m RMS).
You are correct. I think it is more like 4.8 dB (10log(3)), but even if I am wrong, it certainly isn't 20 dB.
 
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HooStat

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Thread Starter #7
Aren't those particular subs designed for use flat on the floor? I thought the intent was to put one under the couch not vertical behind furniture.
They work in any orientation. But they are definitely more stable on the floor. I think I would prefer to see if I can get something 10" wide and use 2 of them. But that might not exist unless I DIY it.
 

sigbergaudio

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#8
You are correct. I think it is more like 4.8 dB (10log(3)), but even if I am wrong, it certainly isn't 20 dB.
Double the number of subwoofers typically give a maximum of 6dB increase (in the frequency range where they are capacity constrained, so typically the bottom end). So when you already have two, you need two more to double it again.
 

andreasmaaan

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#9
You are correct. I think it is more like 4.8 dB (10log(3)), but even if I am wrong, it certainly isn't 20 dB.
If the subs are all next to each other they will sum coherently to give you an additional 20log(3) = 9.5dB for 3 subs, or for 4 subs 20log(4) = 12dB.

10log(n) applies where the signals are not coherent. But where the sources are close in relation to each other or close to equidistant in relation to a listener (1/4 wavelength or closer) the correct formula is 20log(n). The wavelength of 80Hz for example is around 4.3m, and at 40Hz it's around 8.6m and so on.
 
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