bi-amping

I am about to order a 7125, but I have no idea how
to bi-amp axiom m80's using this amp and a parasound
2x125 watt amp (HALO A23) for mains. Doesn't the audio line feed come from one source to one source thus leaving one amp un-used to bi-power main speakers? I think that this may not work. Until the new pre-pro is here, I am using a HK 525 receiver. Any suggestions on how to hook up? The axioms are 4ohm and 400 watt max power... thanks in advance for straight shootin a reply!!

There are two forms of bi-amping: active and passive. Active involves building crossover networks that are applied after the pre-amp and divide the signal into separate signals for the different drivers of the speaker. You are going to be doing passive, which involves retaining the crossovers inside the speaker and instead simply splitting the pre-amp signal with a Y-splitter (see here for a pretty hefty example of such a splitter). The splitter's two outputs then go to the two amp channels that are used to drive the single speaker.

I am currently bi-amping directly from my Yamaha receiver, but I want to switch to an Outlaw amp. My Yamaha RX-V1600 has the pre-amp outputs, so I was looking at getting either the 7125 or the 7700. Since I am only using a 5.1 speaker system with Polk RTi10 mains and Polk in-wall surrounds, I was thinking about getting a 7125 and bi-amping the mains with the 2 extra channels on the 7125. The alleged "hum" issue on the 7700 has kind of scared me off these until I get a pre-pro with balanced outputs. Does getting the 7125 and bi-amping with it make sense?

Thanks,

TL

All of the "hum" issues I've seen with the 7700 have been traced back to ground loops, which is a risk with any amp or receiver, so I wouldn't be particularly concerned about that. On the other hand, bi-amping the mains with the 7125 would be a simple enough task if you wanted to do it.

most people would only bi-amp using two of the same amps. better yet just buy one more powerful amp...

I read an interesting article about bi-amping in a recent issue of HiFi+ magazine. It basically said to use the same amp to bi-amp a specific speaker. In other words it was saying that if you had a stereo amp use the L and R channel from that amp to bi-amp your speaker. It says that level mathcing is extrememly difficult acros two different amps. The article made sense to me.

If you are goign to get a 7125 then use that amp to bi-amp you mains. You would use your HK as a preamp. You could use the 7125 to bi-amp your front speakers (That would use 4 channels of the amp). That would leave you with 3 remaining channels (For center, and surrounds).

Obviously the issue with this is you now have an extra Parasound A23 amp. If you like the A23 just get another one of those and use one of each to bi-amp your mains.

Good Luck. Personally Bi-amping is something that I have always wanted to try, but never gotten around to doing it.

Regards,

Charlie