can i use 2 channels of a adcom gfa-7000 to power a pair of m-80's and the other one for my 150?
no. not a good idea at all.
ok thanks for reply ,do you how good an adcom amp is good,it suposed to be 130 per channel at 8omh and 200 at 4omh
if the amp is at least 3 channels there should be no problem,by the way,isnt that a 5 chan amp?
Dan, it isn't entirely clear what you're asking. You used "combining", but then just described using 2 of the 5 channels of the 7000 for mains and a 3rd for the center, which is just a normal setup. If by combining you were asking if some unused amp channels could be bridged, the 7000 has no provision for that; or, were you possibly speaking of bi-amping the M80s.
i think what he means is combining two of the 4 channels for each speaker, ( to give more power i assume ) and using the 5th channel for the center. By combining i assume he means splicing speaker cables out of both channels into one.
i would like to run speaker wire from 2 channels to one speaker ,2wires 2channels 1 speaker to double the power sence all channels in amp are mono built it that is not posible then what is bi amping?
and to add if that don't work do you think that amp at 130 to 8omh amd 200at4omh will be LOUD powering m-80's in a 20 by30 foot room?8 foot ceiling thanks for info
Daniel,
Some current and vintage models of Adcom power amps (such as the GFA-5002 and GFA-5006) are designed to be "bridgeable" -- you can combine two channels in 180-degrees out-of-phase and drive one speaker by these two channels in a bridge-circuit configuration. But unfortunately, your GFA-7000 is NOT designed bridgeable.
Anyway, although your room is fairly large, 200W/ch would be plenty given the high sensitivity (efficiency) of the M80s.
I just drew up some diagrams on bi-amping and bi-wiring in this thread.. take a look...
http://www.audiokarma.org/forums/showthread.php?s=&threadid=10219
Okay Dan, as sushi pointed out, some amps have provisions for bridging two of their channels into one, which would in fact give you double the power. Since the 7000 doesn't have provision for that, if that was a major reason for buying it, don't.
Bi-amping, which could be done with the M80s since they have two separate sets of terminals to the high and low drivers, doesn't double the power. The way that you would have to do it, without an external crossover, would have minimal if any benefit. Each amp channel would still have to carry the full range signal and the power of only one amp would be available to a driver, not two. Don't bother.
There are some cases with speaker that biamping would improve sound quality of a speaker. For instance with a low power amp (less than 100w @8 ohms) attached to a speakers that needs lots of power (Hales, Maggies, Thiel are some that come to mind) the sound quality improves by biamping those speaker having one power to the lower drivers and the other to power the highs. One thing to note though the M80 are pretty efficient and are not power hogs ... having the the 7000 has ample power the difference in sound between driving standard stereo to driving biamped maybe be negligeable. Mind you if I had extra power that is not being used why the hell not...I would definitely biamp the M80 using up 4 amplification. Use the last amplification for the centers. And i do know it doesnt mean that it is 2x louder. It is not. (I do have me center biamped with 2 x 60w) But it does sound nice.
In reply to:
I do have me center biamped with 2 x 60w
Blimey! Do ye now? Arrrr...
Sorry matey ... watched Pirates of the Carribean just recently.