using a 4 ohm passive xo...in an 8 ohm system..

currently, i gotta project on going.. im building 2 passive sub boxes...

the only thing is i can't find any passive sub xo's @ 8 ohms..

so im contemplating getting an 4 ohm'er...cause its abundant and vailable..

the specs on it are..

200 watts rms
crossover @ 120hz
12db/octave slope
4 ohm..

how do these specs, when both the sub and the power being supplied @ 8 ohms...

(so far what ive been able to figure out that.. the passive xo is in a 2nd order linkwitz-riley setup...
thus the coil mH would match an xo of 240hz @ 8 ohms. but the cap doesn't..)
 
ChesterFuzzin' said:
passive sub xo's

Don't do it -- i firmly believe that any XO below 200 Hz should be active -- it makes a HUGE difference.

To get any quality in the coils & caps needed for an XO at that frequency, some careful shopping (ie ApexJr) could yield you a pr of plate amps for not a lot more -- maybe even less -- than quality bits for a passive XO.

and i can't really recommend generic XOs at all since no driver has textbook constant R impedance.

dave
 
i just tested it out... sounds fine..

I just hooked up a spare 8 ohm 12" woofer i had lying around to the 4 ohm xo...and connected it to the left channel of my receiver..

and played a bunch of tunes to test it out...

it sounded fine... ( most of the higher frequencies i wanted cutout..were cutout...)...

anyhoos.. i further looked into the setup.. and the way i see it

the passive xo running @ 8 ohm basically would have a crossover @ 240hz..
but have an octave slope somewhere between -6 and -12 db.