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
jeffreyds
111 posts
 
What tubes are you using?
jbrrp1 OP
215 posts
 
They are tubed with the Kron KR-300B LSX tubes from Czechoslovakia.
darkmoebius
899 posts
 
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.

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