How to deal with microphonic 300B tubes.

What tubes are you using?

They are tubed with the Kron KR-300B LSX tubes from Czechoslovakia.

Herbie's Tube Dampers wouldbe the first thing I'd try. Call Herbie first to find out which one's would work best with the KR's. I think the KR internal(and external)structure is more heavy duty than TJ's, WB's, etc.so may need a special version.

I tried a friends on a few of my tube amps recently and the improvement was easily noticable. Clarity, focus, and silence that I had no idea was missing. As a result, I've ordered a fullset for my ams and preamp.

Do an archive search hear and on Audio Asylum's Tube forum for user opinions.

Herbie's Audio Lab

6Moons review(1/2 down page)
Positive Feedback review
TNT Audio review(1/2 down page)
Enjoy The Music review(1/2 down page)

Jay,

I had a similar problem with KR 300b XLS's in my Cary 805c's. You may want to try KR 842VHD's. I found the 842's to not have any problems with microphonics in my system. I think they will work with the LX-20 version of your amp, but make sure to check with Cary.

Be aware, though, that the 842's will sound much different. I found them to be smoother and warmer sounding, but with some loss of bass impact and musical weight.

Jeff

Thank you for your input. The Halo do seem worth trying - - I have used dampeners before, and they always seemed to help. And the Halos are designed to let the tube still convectively cool, which I like.

The ringing I have been hearing is a fair bit more than I've ever encountered from a tube before, and very focused on a frequency. Maybe the Kron tubes are more prone to this, I don't know.

I don't believe that the Cary's can run the 842's. They don't say this in the manual, but they do warn you not to try any other 300B's other than the Krons.

I'll have to try out some of Herbie's magic.

Jay