How to Bi- Amp old McIntosh gear.

This might sound like a dumb question but....
I have a pair of Joseph Audio RM-25's which I can remove the jumpers on and run each speaker with one amp. I have 2 McIntosh MC2505's and a C-28 pre-amp. Can someone please tell me the correct or best way to wire this combo up. McIntosh says one one, Audio Classics another. When I change bass or treble, it changes it in both speakers, even though I am using right or left controls. Please put this into simple terms, thanks.

Sounds like your speakers have two sets of posts for the same crossover. I think mine are the same which I have determined makes biwiring a questionable proposition. Bi-amping my be in the same predicament. Hope others can confirm this for me too. Arthur
Yes the Joseph's have 2 sets of posts on each speaker for bi-amping. I have it set up now and it sounds great. Each amp has 2 channels, each channel runs one set of speaker posts. My question is what is the right way to connect the equipment?

Hi Brian,

I bi-amp my Maggies with 2 rebuilt Hafler amps now. You'll find that there are two schools of thought on how to bi-amp:

Vertical: Here you use one stereo amp to drive the low and high side of one speaker. One amp per channel, so to speak. This is the way I do it with the Maggies. One channel to the woofer and the other channel to the tweeter.

Horizontal: Here you use one stereo amp to drive one woofer on each left/right speaker. The other stereo amp is then used to drive the tweeters. I've tried this but prefer the Vertical wiring approach.

You might want to visit the Vandersteen web site as I recall he used to have a much more detailed discussion on his recommendations with his speakers, which I used to have.

Hope that helps.


at one time I was using a Quad set of mac mc 30,s to drive Joseph audio rm25si,s.I settled on the horizontal approach as although amp gains were close the two pairs were of slightly different vintages and used the set with black gate caps to drive the tweeters and the pair with mostly rels to drive the woofers,if both of your amps for sure identical in every respect,try both and use ears to decide.