2 subs twice as loud?

[simon21 10+ year member]

I would think by intuition that by having 2 subs it would get twice as loud as having one sub, with each sub getting the same power. I have also heard that a second sub will make it only 5% louder. Can anyone explain this to me?

Thanks

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[davidfre21 5,000+ posts]

ive always had the same idea, but it cant be true because there would be new sound records. it think if u double everything u gain like 3dbs

 

[cjj2d 10+ year member]

I am wanting to add a second 15 mag and I already have a matching PPI amp for it. Just have to find someone to sell me their mag. **** things are already sold out.

 

[helotaxi 5,000+ posts]

It will ad 3dB, same as doubling power. 3 dB is twice as loud since the dB scale is not linear. Your ear is not linear either so it requires 10dB increase for it to sound twice as loud generally and that also means 10 times the speakers or 10 times the power.

 

[Berry47 10+ year member]

It will ad 3dB, same as doubling power. 3 dB is twice as loud since the dB scale is not linear. Your ear is not linear either so it requires 10dB increase for it to sound twice as loud generally and that also means 10 times the speakers or 10 times the power.

This is 100% true. Noise grows on an exponential scale.

 

[DirtySchemer 10+ year member]

I've been a bit confused on this too. I've heard that doubling the speakers will increased output by 3db, but I'm not clear on the assumptions. Does this mean that:

2 12" sub receiving 100 watts each is 3 db louder than 1 12" sub receiving 200 watts?

or

2 12" sub receiving 200 watts each is 3 db louder than 1 12" sub receiving 200 watts?

 

[kingpin_jeffie 10+ year member]

This is 100% true. Noise grows on an exponential scale.

actually its a logarithmic scale.

 

[Pete 10+ year member]

the dB scale is logarithmic.

1 12" with 200 whats is 3 dB quieter than either 1 12" with 400 watts OR 2 12" with 200 watts.

It is also true that 3 dB is twice as loud, but our ears perceive twice as loud as 10 dB.

Oh, and as for it being easy to achieve new spl records... you can quickly see how out of hand it would get to raise 3 dB when you get to high spl and power levels.

Start with 2 12" subs and 500 watts. to add 3 dB you need either 4 12" subs OR 1000 watts. To add 3 dB again you would need to use 8 12"s or push 2000 watts. Add 3 dB again and you have a total of 16 12" subs or 4000 watts. One more time would be 32 12" subs or 8000 watts. We added either 30 subs or 3500 watts to gain a total of 9 whole dB... ouch. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[mud 10+ year member]

A deciBel tenth of a Bel, the original measurement of sound/volume/loudness/whatever. Mathematically, the number of bels is calculated as B = log10(P1/P2) where P1 and P2 are power levels.

 

[Razza8503 10+ year member]

the dB scale is logarithmic.1 12" with 200 whats is 3 dB quieter than either 1 12" with 400 watts OR 2 12" with 200 watts.

It is also true that 3 dB is twice as loud, but our ears perceive twice as loud as 10 dB.

Oh, and as for it being easy to achieve new spl records... you can quickly see how out of hand it would get to raise 3 dB when you get to high spl and power levels.

Start with 2 12" subs and 500 watts. to add 3 dB you need either 4 12" subs OR 1000 watts. To add 3 dB again you would need to use 8 12"s or push 2000 watts. Add 3 dB again and you have a total of 16 12" subs or 4000 watts. One more time would be 32 12" subs or 8000 watts. We added either 30 subs or 3500 watts to gain a total of 9 whole dB... ouch. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Actually thats 12dB genius //content.invisioncic.com/y282845/emoticons/uhoh.gif.c07307dd22ee7e63e22fc8e9c614d1fd.gif

 

[Urmama 10+ year member]

the dB scale is logarithmic.1 12" with 200 whats is 3 dB quieter than either 1 12" with 400 watts OR 2 12" with 200 watts.

It is also true that 3 dB is twice as loud, but our ears perceive twice as loud as 10 dB.

Oh, and as for it being easy to achieve new spl records... you can quickly see how out of hand it would get to raise 3 dB when you get to high spl and power levels.

Start with 2 12" subs and 500 watts. to add 3 dB you need either 4 12" subs OR 1000 watts. To add 3 dB again you would need to use 8 12"s or push 2000 watts. Add 3 dB again and you have a total of 16 12" subs or 4000 watts. One more time would be 32 12" subs or 8000 watts. We added either 30 subs or 3500 watts to gain a total of 9 whole dB... ouch. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

not in this world //content.invisioncic.com/y282845/emoticons/smash.gif.499e08a4a35ffaf54f4c8194fb8fe8ed.gif

too many variables to break it down that simple, + law of diminishing returns

as far as are ears percieving a 10 dB change as twice as loud, that scale is not linear, and frequency dependent

 

[Pete 10+ year member]

OK razza... 12 db, I doubled it one more time than I thought I did, I'm stupid.

Irmana - I agree this is completely over simplified. Mathmatically it is correct assuming that each sub has the same amount of air space, all subs are exactly in phase, you are playing only one frequency, there is no lack of power for the amps, etc. I was just illustrating the principles that answer the question that started this thread.

 

[BoomFoo 10+ year member]

I love complicated crazy talk!!!!!

 

[simon21 10+ year member]

2 subs wouldn't cancel each other out to some degree?

 

[nweibley 10+ year member]

Not nearly as much as they would constructively interfere.

Another thing: the human ear is subjective. The whole 10dB is just a good rough guide.