My subwoofer challenge

nist7 · Post by **nist7** » Fri Mar 25, 2005 11:04 pm

I pose this question because I want to use my 80wx4 amp for both the front stage and rear fill. I am leaning towards Shivas. But Tempests, Atlas, and maybe others *might* work also in this application?

Here is the scenario: two 12" or 15" subwoofers in about 4 cubic feet of total, sealed volume with polyfill. Each sub will have about 80 watts of available RMS power. And no, that was not a typo. I mean eighty watts.

The subwoofers must be able to output sufficient SPL to compliment a similarly powered set of quality, 2-way comps in a small coupe. The subwoofers will be firing into the vehicle cabin with the backseat down.

Can this be done?

If yes, how?

If no, why?

Jonathan · Post by **Jonathan** » Fri Mar 25, 2005 11:12 pm

If you're able to, why not just bridge the rear channel and run the sub off of that? You'd get more SPL out of one sub with that much power than you would with 80 per sub. Either of those subs would be very good with that level of power, too.

nist7 · Post by **nist7** » Fri Mar 25, 2005 11:19 pm

Jonathan wrote:If you're able to, why not just bridge the rear channel and run the sub off of that? You'd get more SPL out of one sub with that much power than you would with 80 per sub. Either of those subs would be very good with that level of power, too.

Someone needs to invent more efficient subwoofers!

But yes Jonathan, my bridged rear channel would give out about 140w of RMS power, which would be plenty.

I think one of my research projects in college will be to build a subwoofer that is able to output an unprecedentedlevel of SPL with low power feed. Should be interesting

Jonathan · Post by **Jonathan** » Fri Mar 25, 2005 11:28 pm

The Shiva works very well with low power, you'll just get better results out of a single sub with higher power than two subs with less. I thought your amp would be along the lines of 300-320 bridged into 4 ohm, I was just basing that assuming the 80x2 would be at 4 ohms, though.

audiobass10 · Post by **audiobass10** » Sat Mar 26, 2005 6:26 am

A single Atlas 12 or 15 would be my pick. Both are extremely efficient and feature xbl^2.

ridr4lif · Post by **ridr4lif** » Sat Mar 26, 2005 8:24 am

Hmm...sounds like an interesting project and i cant wait to see it unfold.
But i agree w/ Jonathan about bridging 2 of the channels and running a single 12 or 15. You will most likely be louder w/ that setup.

TEDD

Post by **GlassWolf** » Sat Mar 26, 2005 1:32 pm

same initial thought I had.
bridge channels 3 and 4, and run a single 12" sub.
The sub's sensitivity (not efficiency, see FAQ section) is only going to have so much effect when you're driving that much cone mass. It takes power to get a strong enough magnetic field to control a large speaker accurately. Otherwise you get a sloppy sub due to low power, which will give a similar result to having an amp with a really crappy damping factor.

I've run a pair of older LE12D Cerwin Vega 12" subs with 160wRMS each from a 2 ohm stereo Orion 280GX and they hit very hard in ported enclosures in a small hatchback. One 12" sub with ~150wRMS should only be about -4dB down from that which will still be a hard hitting system, and it'll only take up a little over 2cu ft in space from your trunk or hatch, too.

nist7 · Post by **nist7** » Sat Mar 26, 2005 1:47 pm

hmmm....a 12" Atlas sounds good to me right now.

Maybe polyfill should also be used to 'enlarge' the enclosure?