SPL values combined vs dissimilar

Vaughan · 26th June 2009, 04:10 PM

Hi there,

Just wanted to ask a question in connection with setting up subwoofers : either gain matching or level matching.

It's been said that if you gain match two subwoofers, the SPL values will differ if both subwoofers are placed in different locations.

So obviously the SPL generated per sub will be dissimilar.

The other approach is to level match. Calibrating each sub to equal SPL levels. Now if both subwoofers were to generate equal SPL levels, you will achieve a 6 dB output advantage (especially if in phase).

Now what I would like to know from some here is : if you combine two dissimilar dB values, you won't gain that same 6 dB output (even if both subwoofers were in phase) ?

What I know about coupling and maximizing output is that in order for that to happen both subs would need to be in phase and in level.

Just want to have some discussion on this from the physics majors....

Vaughan · 26th June 2009, 07:42 PM

Anyone have any views on this ?

weltersys · 29th June 2009, 09:49 PM

Vaughan,

The combined level of two non-correlated dB values varies from a maximum of 3 dB gain to less than 1/2 dB gain over the larger amount when the difference is 10 dB.

Do you have a specific question?

26th June 2009, 04:10 PM	#1
Vaughan diyAudio Member Join Date: Jan 2004	SPL values combined vs dissimilar Hi there, Just wanted to ask a question in connection with setting up subwoofers : either gain matching or level matching. It's been said that if you gain match two subwoofers, the SPL values will differ if both subwoofers are placed in different locations. So obviously the SPL generated per sub will be dissimilar. The other approach is to level match. Calibrating each sub to equal SPL levels. Now if both subwoofers were to generate equal SPL levels, you will achieve a 6 dB output advantage (especially if in phase). Now what I would like to know from some here is : if you combine two dissimilar dB values, you won't gain that same 6 dB output (even if both subwoofers were in phase) ? What I know about coupling and maximizing output is that in order for that to happen both subs would need to be in phase and in level. Just want to have some discussion on this from the physics majors....

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26th June 2009, 07:42 PM	#2
Vaughan diyAudio Member Join Date: Jan 2004	Anyone have any views on this ?

29th June 2009, 09:49 PM	#3
weltersys diyAudio Member Join Date: Jan 2008	Vaughan, The combined level of two non-correlated dB values varies from a maximum of 3 dB gain to less than 1/2 dB gain over the larger amount when the difference is 10 dB. Do you have a specific question?

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