Monoblocks did not work

I don't know if your CA400s are also balanced or not, but I recently vertical bi-amped a pair of McCormack amps using RCA ICs, and I accidently switched one amp to the balanced mode and got sound like you describe.

Do the CA400s have balanced switching of some kind? Other than that, I would make sure all speaker cables are attached to the correct speaker and amp terminals for the way the monos need to work. Good Luck. Craig

Hello Nilthepill:

Yo are on the right track except you strapped your amps mono. By bridging you increased output power hower reduced current from the amps thus losing some control of the speaker by the amplifier as now the amps see the load at half the previous impedance. In other words, If your speakers are a 4 ohm load, in bridged mode each amp sees a load of 2 ohms. This would account for the bright and hardness you now experience!

If you can biwire your speakers, remove the jumpers and do so. I am assuming that you have one long run of interconnect, and have the amps next to the speakers. If so, you'll find with a short run of speaker cable you can use almost anything! As to splitters, even a cheap pair of Rat Shack splitters will give you an idea of what is possible.
Use them on the amp end and then use one channel of each amp on the woofers, and the other channel of the amp on the tweeters. I can virtually guarantee this will result in improved sound!

Paul

Thx you all for your input. Garfish, Classe does have switch for mono/stereo operation as well as Balanced/RCA operation. Am running Balanced. Radio shake would have Y-splitter for balanced configuration? Will check it out. Redwiki, I don't know about opening the amp and bridging the RCA's( I am no techno either).

I think this is what I should do to go towards vertical bi-amping. Use the other pair of speaker cable and try out the biwiring with my existing STEREO amp. If the sound does not deteriorate, I try Vert biamping using radio shake y splitter. If works (meaning not deteriorate ) get the remaining pait of straightwire IC( Same as my existing brand, works great in my system) with straight wire Y-splitter at premap end and hope for best.
If not use the extra amp for (open a welding shop or something) my rear Dunlavy surrounds and just use he Multichannel Classe CAV-150 for cente channel only. Oh well! thx all.

Skip the bridging and go straight to bi-amping. While active biamplification is best, you can still get some gain by doing this passively. As you've noticed, most amps do not sound good when bridged. Sean
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Nilthepill:

Shame on me, I assumed you were using single-ended interconnects. Rat Shack will not have any balanced Y
adaptors. Tough call here. I still believe your sound will improve from biamping, however you will need balanced y connectors (not sure these are available) or a second run of balanced cable (if) your preamp has 2 sets of balanced outputs! Good luck!

Paul