help with a bandpass enclosure

idahoxj

Member
2005-06-11 4:49 am
idaho
Hey guys, I am building a sealed rear chamber bandpass enclosure for my jeep and when I try to figure out the port size I get a rediculously long port size. I think its becuase I am using just the front chamber volume. Should I use the total volume of the entire box?
These are all the specs.

The box
vf=3.664ft^3
vr=9.626ft^3
Qpb=0.88
Fb=28.51
gain=2.39
F(l)=17
s factor= 0.6
I am planning on the box being roughly 45"x17"x32"

The speakers
Qts=.72
Vas=4.908
Fs=23.2
Qes=.84
SPL=85

Thanks in Advance.
 
what was the diameter of the port you wanted? If you go to a smaller diameter the port will get shorter. But as the port gets narrower the air speed picks up, supposedly when this gets to high you can hear the air move. I have built speakers with a resulting air speed that should be audible, but by that time the music is so loud I can't hear it. I realize this dosen't answer your box volume question but it may come in handy if your numbers are good.
 
You're trying to tune it way to low. Tune it around 50hz or higher ... unless you want your in-car response to "peak" at about 20Hz and not play much of anything above 30.

if the vas is in ft^3 then I should one sub looking nice in ~1.5ft^3 rear and 2.9ft^3 front tuned to 48Hz via 6"x6"x8.375" D port ... might play a little low for most people tho ... passband of ~40Hz ... 30Hz to 70Hz
in-car should be pretty mean from mid 30's to mid 50's with a gradual slope above 50 ...