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cunokyle
05-20-2007, 05:23 PM
Ok, I am using WinISD to help design a purely SPL enclosure for events. The only thing is, that I have entered EQ info for cabin gain(Linkwitz transform) and now all my calculations are returning similar SPL levels for every tuning frequency. Not sure if I did it correctly or if I should just not enter the EQ info to the program to determine tuning frequency.

My internal vehicle length from wall to windshield is a little over 7ft(2.2meters) so I used the following info:
internal car length = 2.2m
Linkwitz transform
f0 =80
fp =15
Q0 =0.707
Qp =0.707
from http://linearteam.proboards12.com/index.cgi?board=winisd&action=display&thread=1087022128.

Now however, my SPL number in WinISD is always pretty much the same +/- a half decibel or so from 30hz to 60hz no matter which tuning frequency I tune to. Is this an accurate result? Will the tuning frequency have pretty much no impact on SPL numbers? That doesn't seem right to me, but maybe I am missing something.

cunokyle
05-21-2007, 11:56 PM
Looks like I may just to pay more attention to things. The site there states that the SPL numbers are not correct when using the eq stuff with WinISD.

Quote:
WARNING

The Following graphs are incorrect when using a Linkwitz transform to predict "Cabin Gain"
Transfer function phase
Group Delay
Maximum SPL
Amplifier apparent load power
Cone excursion
Passive radiator - all
Port air velocity
So, looks like I will have to design it without cabin gain info plugged in.