Question on power for DIY 2x15 cab

bw79072 · #1 12-20-2012, 03:02 PM

I am about to begin construction on a 2x15 similar to johnk_10's Starliner, but using Emi Legend CB158's instead of the 3015's.
Here's the question...the Legends are rated 300rms/600program watts each...as far as amp power is concerned, should I rund something in the 600w range to match the rms rating, OR 1200w to match the program rating, OR something somewhere in between? All input (especially from the guru guys) will be greatly appreciated.

BassmanPaul · #2 12-20-2012, 03:17 PM

Do you realize that the cB158s might not work very well in John's cabinet design?

bw79072 · #3 12-20-2012, 04:03 PM

Similar, not a direct copy...winisd shows almost flat from 50hz up to about 2.5k, and 128db with 450ish watts in 6cu.ft. @ 45hz, iirc...numbers may vary a little, am on my phone right now...

wcriley · #4 12-20-2012, 04:12 PM

Well, then it sounds to me like 450 watts would be plenty.

Bass_Pounder · #5 12-20-2012, 04:22 PM

Quote:

Originally Posted by bw79072

Similar, not a direct copy...winisd shows almost flat from 50hz up to about 2.5k, and 128db with 450ish watts in 6cu.ft. @ 45hz, iirc...numbers may vary a little, am on my phone right now...

If your running specs in WinISD, it should tell you where your displacement power limits are.

bw79072 · #6 12-20-2012, 04:29 PM

The 425w or so is where it hit xmax...so anything over that would be an invitation to disaster? That was my thinking, but wanted confirmation from those who are more learned on the subject.

rpsands · #7 12-20-2012, 04:33 PM

It doesn't work exactly like a sine wave would seem to indicate. Firstly, most basses put out a lot more at the first harmonic than the fundamental. Secondly, basses have a much higher crest factor than sine waves.

So a bass wave might have a peak of 800 watts but the average wattage might be more like 200. Or something like that.

Bottom line, get something you like that sounds good and turn it up until it's loud enough or you hear the speakers protesting.

oerk · #8 12-20-2012, 04:34 PM

Meh. You can't rely on the amp's numbers. Some amps rated at 450W won't put out anywhere near that wattage.

I would go with a 500W+ amp, and try to keep an ear on the speakers to hear when they start distorting.