2. amps-preamps
  3. 1131597962

How to deal with microphonic 300B tubes.

I have a used set of Cary CAD-300SE LX-20 mono amps, and I just love them with my Coincident Victory speakers. But I occaisionally get a weird, intense ringing microphonic from them, especially noticable when an FM announcer's voice hits just the right pitch.

I have them just sitting on my tiled floor, no attempts at vibration stands yet. I'm sure this could help a bit, but I am also thinking that tube dampening could be needed.

Any suggestions? Are there appropriate tube dampening strategies for 300B's?

Thanks,

Jay
jbrrp1

Showing 2 responses by jbrrp1

jbrrp1 OP
423 posts
 
They are tubed with the Kron KR-300B LSX tubes from Czechoslovakia.
jbrrp1 OP
423 posts
 
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
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