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Cabin Gain??? jonathan, fishy, anyone....HELP!!!

 

cabintrouble
Unregistered guest
ok,

i ran my sub/enclosure combo in WinISD, it said that the SPL (under the "SPL" tab, not the "max spl" tab) that the sub should put out w/ 500w is 114dB. But i had my SPL metered and i got 131dB at headrest. Assuming that i put all the info about the box into WinISD correctly, does this mean that i have a cabin gain of ~17dB???
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2087
Registered: May-04
Pretty much. WinISD isn't really all that good for guessing SPL, just see how much power it takes to hit 150 :-) Anyway, you probably have a good amount of cabin gain, 17db could be about right at a certain frequency.
 

cabintrouble
Unregistered guest
if i use WinISD to build a new box and it says that the sub will put out ~117dB, then i should still get ~17dB of cabin gain at the original frequency that i hit 131db at....right?

i'm gonna tune my box higher if it will give me the increase in SPL, and i may build a bigger box. would that help me increase SPL???
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 2093
Registered: May-04
Both a bigger box and higher tune will generally net more SPl.
 

cabintrouble
Unregistered guest
in general, about how many dB would a bigger box net.

i ask because in WinISD, it says that my current box has about +3dB gain and a new box i designed have about +8dB. could these figures be correct?

ps,
both are ported boxes. one is 2cu ft tuned to 34hz. the other is ~6cu ft tuned to 47hz.
 

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 360
Registered: Sep-04
Cabin gain theoretically "begins" at a certain frequency and increase by 12 dB per octave. In other words at frequencies below this every time your frequency is halved the acoustic "power" is increased by a factor of four........ theoretically.

This article explains it pretty well:

http://www.diysubwoofers.org/projects/vitara/

BTW, has anyone used this guy's spreadsheet? I loadeed Excel and gave it a shot but became completely lost.

It really would be nice if I could get an enclosure design system goin that could include at least an approximation of how cabin gain affects output.

Aside from home applications I'm beginning to think winISD is only good for comparing car subs not designing enclosures from scratch.

And don't say LEAP. That be way too expensive.

:-)

-Fishy
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