Ringing heatsinks

One of my current amplifiers is a Classe' CA300 and while performing a cable swap, I accidently hit the heatsink with my finger nail and it rang like a tuning fork. I tried the same manuever with an older Classe' DR8 amp and it didn't ring like that. Then I wondered what effect this had on the sound of the amp since the transistors are mounted to the other side of the heat sink. I inserted a rolled up towell on either side of the amp between the shelf and the heat sinks and on top of the heat sinks rested some pieces of mdf wood to dampen the ringing. This does not pose a heat problem with the CA300 as the fins run pretty cool. The sonic change is very noticeable eliminating a glare in the treble and a vast improvement in focus through the vocal regions. The overall presentation is smoother and more lifelike. I'd like to hear from anyone else with a CA 300/400 or another brand with ringing heat sinks as to whether they find any improvement in the damping I've suggested.
Ag insider logo xs@2xrhljazz
Michael Green of MGD fame spoke to me about this during a conversation. While he wasn't specifically talking about Classe' amps, he mentioned that things of this nature DO greatly contribute to the sonics of components. In one specific case, he was brought in by an un-named manufacturer or electronics as a consultant. It seems that they were intrigued by his theories and wanted to see what "knowledge" he could pass onto them in terms of improving their products. I guess that they had a nagging problem with a specific amp sounding "metalic" and having a ringing or "glare" problem. Michael told them to "re-resonate" their heatsinks and the problem would disappear. The only thing that "disappeared" was Michael out the door. The electrical engineers just about shoved him out of the place at a high rate of speed. I guess that they thought his theory was just a little "bunk". Sean
Jazz: I read somewhere on the web that owners of the Bel Canto EVO amp have had good results damping the sinks as well as other parts. The info may be at Audio Asylum (though I am not certain) and there was mention of specific materials that worked well that you may want to try.
I think I read somewhere that one of the tweaks employed in
the Belles "hot rod" version amp was dampning material for heat sinks. Perhaps a Belles amp owner would comment on this.
I must admit that I have never heard of this. Intriguing idea. I have a Classe CA-300 that I am using in stereo to power the bass woofers of my speakers. After reading you post, I tried the ping test and it seems that they do resonate. The amp sits on an amp stand so dampening the heat sinks are going to be a bit tricky. I'll report back any findings. Thanks for your post! Regards; -Jerie
If you go to Soundstage.com and look at the review for the Belles Hotrod amp, the reviewer suggests putting rope caulking material on the underside of the fins. I just bought a box at Sears Hardware for $3.50 and am going to try it.
Post removed 
The Belles Hot Rod employs Cramolin damping compound to damp resonances. Andy Bartha sells something he calls "whatchamacallits" (I don't know what these are, nor how to access his website, although he supposedly has one) anyway these are also used for heatsink resonance damping. Might be worth a call to 954-583-7866 to find out more? Unless perhaps someone here has experiences to share please?
Doug Blakburn's Soundstage.com review of the Belles Hot Rod 150A speaks about your exact problem. He used the Cromolin VC Damping material. Soundstage.com also has a review of the Cromolin material. It may be worth a look.