2. amps-preamps
  3. 1131913685

Bi-Amping

Hi everyone,

Well I steped up to dual power amps and bi-amping my custom made (self built) speaker system that I have finally finished- Cerwin Vega 15 inch subs, Vifa 8" bass and 6.5 Mid bass, dual Vifa 3 inch SoftDome mids, with a Morel 30's for the tweeter. The subs are @ 80Hz (via the B&K), the speakers are crossed @ 300Hz, 500Hz, 700Hz, and 3200Hz- 2nd order for the lows and 3rd order for the highs. One amp runs the subs and the other the speakers.

I am using two (2) Proton D-1200's, a B&K PT5 preamp, with an Audio refinement CD player. I am running Monster MCX 2s wire (4- 15' foot runs), Audio Quest power cables, and Monster M850i Interconnects, this is connected to a dedicated 20A wall outlet.

My room size is 28x14, shot gun style, painted dry wall, and half carpeted/harwood flooring, 8' room height.

My question is: I was expecting a more powerful sound then what I have presently. While everything did open up, it seems the DB output did not increase substantially, as a matter of fact, it seems I must now nearly max the volume control on the B&K to achive similar output when I was using a single amplifer. All be it, the sound is more refined and much tighter, the DB output did not increase. And I am concerned that the B&K is having trouble outputing enough voltage to run two amplifiers.

Is this the norm? Am I not suppling enough "juice" to the amplifiers via the wall outlet? Or, do I have to large a "hole" between the subs and the Speakers?

While this does sound very impressive, I am not as "jazzed" as I thought I would be.

Any ideas, comments, help?
alpha_03

Showing 1 response by gregm

gregm
3,411 posts
 
But I do not understand why the pre-amp needs to be cranked all the way up just to get nearly the same sound (dB) I had previously
Your ears are fine, and yr setup seems correctly done. What's happening is you're losing energy in the pre->2amp connection. That's because you have halved the input impedance of the amps by putting them in parallel -- i.e. the "combined" load the pre sees is now very difficult and it is struggling to provide the appropriate amount of energy (and isn't making it). The two amps together are sucking up the pre. Remember, when you halve the voltage, the wattage drops to 1/4th.
The rest (room, you need a shrink, 3way xover, etc) don't apply;^) Cheers!
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