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jacko
09-28-2005, 04:52 PM
What is the general rule for subs being in big, small, ported, or sealed boxes and creating an SPL or SQ box based on T/S parameters alone. I know that qts and vas and fs has a lot to do with it... other than that i'm a total noob? If anyone could explain or post a link THANKS!
-Tyler

squeak9798
09-28-2005, 04:56 PM
Sealed:

Qr = Qtc/Qts
Vr = Qr^2-1
Vb = Vas/Vr
Fb = Qr*Fs
F3 = Fb*((1/Qtc^2-2+((1/Qtc^2-2)^2+4)^0.5)/2)^0.5

If Qtc>(1/2)^.5
then dBpeak = 20*log(Qtc^2/(Qtc^2-0.25)^0.5)
Else dBpeak = 0

where,

Vb = net box volume (litres)
Fb = box resonant frequency (Hz)
F3 = -3dB frequency (Hz)
dBpeak = maximum peak or dip in system response


Ported:

Vb = 20*Qts^3.3*Vas
Fb = (Vas/Vb)^0.31*Fs
F3 = (Vas/Vb)^0.44*Fs
dBpeak = 20*LOG(Qts*(Vas/Vb)^0.3/0.4)

where,

Vb = net box volume (litres)
Fb = box resonant frequency (Hz)
F3 = -3dB frequency (Hz)
dBpeak = maximum peak or dip in system response
Dv = internal diameter of port (cm)

squeak9798
09-28-2005, 04:59 PM
General rule of thumb is Qts of .4 or above is best suited for sealed, below that best suited for ported.

Along with that, EBP (Qes/Fs) of closer to 50 is better suited for sealed, closer to 100 is better suited for ported, and in the middle can go either way.

Chevyaudio
09-28-2005, 05:10 PM
Squeak, look at the Sealed spl box size recomendations on the Type R, why are they so small, and also those are all Gross box volumes, so after displacement, the 12 inch type R will be in about .35-.4 cubes....WTF?

http://img279.imageshack.us/img279/2412/vvvv2cu.png

tRiGgEr
09-28-2005, 05:20 PM
That graph is .5ft^3 sealed. That is normal. And it needs to be .5ft^3 after displacment...

Chevyaudio
09-28-2005, 05:23 PM
at the bottom of the first chart it says all volumes are Gross volumes.

Chevyaudio
09-28-2005, 05:23 PM
.5 seems a little small to me.....

Chevyaudio
09-28-2005, 09:01 PM
Jmac that is the Chart on Alpines Website. I was just looking around online and i found it.