Adcom 5800 - Nelson Pass, others
 

I'm baffled as to why my 5800 is having such a tough time driving my ML CLS2A's(glary mids and tizzy treble). Granted, the CLS impedance dips to less than 1 ohm @18-20kHz but I always thought the beefy power supply and 16 output devices/ch of this beast could handle the job. Can this be remedied by bias adj or some other relatively easy tweak? Appreciate any input?

Jerry

I think you at least want to check on the bias value of the 5800.

The prototype had a lot of capacity and a very healthy bias, which
ordinarily would allow it to do the job. I had a pair of ML Monolith
variants at the time it was developed, so I know it worked well
into them.

The Martin Logan CLS went through a few changes during its lifespan and I didn't hear all of them, but to be quite frank with you I never found them acceptable. Why? Exactly what you describe--glassy, forward upper midrange and less than optimal top end.
In other words, are you sure it's the amp that's the problem?
Speaking only for myself, I wouldn't take a pair of CLSs on a silver platter. They were actively offensive to me. Yes, I know they reviewed well and some people swore by them, but to me...well, you get the idea. Don't blame the amp if it's the speaker.

Grey

Hi Grey

I know it's the amp because my VSP Trans/Mos 200w works very well with the CLS. A friends Hafler 9505 Transnova also was quite good. BTW, one must use tubes somewhere in the chain of amplification when running CLS'S. I use an AL MOD 2D pre. Perhaps your listening experience with the CLS was affected by incompatible power amplification. You should'nt go all solid state.

Jerry

Thanks Nelson. How high should I reset the bias?

Jerry

Is yours the version with the fan?

The first thing to know is that I adore tubes. The second thing to know is that I own tubes. The third thing to know is that I've designed with tubes. That said...no speaker should force you to listen to use tubes in order to sound tolerable.
If you're trying to use a warmish sounding amp to tame the aggressive mids and highs of the CLSs, consider an Aleph.

Grey

Yes, it has the fan.

I love tubes also. In fact I Wish I could afford a high powered tube amp to drive my CLS but I think you're missing the point. Their notoriously tough load can give many so called "high end" solid state amps a hard time. And oddly enough, just for grins we tried a Berenger Euro that my friend uses strictly as a sub amp. It did a respectible job sonically(this amp is NOT euphonic sounding), because it could deliver enough volt/amps to handle the nasty impedance of the ML. The hard aggressiveness is not a speaker issue, but rather an amp issue.

Jerry

>>BTW, one ohm speaker can design only moron
Upupa Epops, 4\2006

http://www.diyaudio.com/forums/showt...944#post898944