Amp heat sinks are ringing


I have been working to reduce the slap echo in my room by using quick hand claps, and various foam panels to attenuate the noise. I have discovered that my Classe CAM 200 monoblock heat sinks are actually ringing- they can be excited by handclaps, and heard across the room. There are 10 heat sinks per amp, about 2" deep by 8" high. Running my fingers along the heatsinks makes them ring like a bell!

I am concerned that this ringing might be excited when I am listening to the system, and may add extra treble noise.

Does anyone have any suggestions for damping out the noise? I am concerned about using a material that can withstand the heat, and not impede the airflow?

thanks for your help!
gnobber
All SS amps do this to varying extent. While you can cure / reduce the ringing, doing so will also change the sound of the amp. If you doubt that this could affect the sound, take some vibration readings at the output device using an accelerometer. Those that are "tweaky" have known about this for a LONG time. Nobody has mentioned it as solving this gets to be a pain in the ... You have to find a way to mass load the fins without reducing their natural convection properties. If done properly, you will solve the problem and increase cooling capacity, but it is neither pretty nor simple.

This is why i mentioned building "sound absorbing covers" to go over one's rack in a DIY rack thread. Obviously, some type of ventilation system must be used though. The other alternative is to do what both Dekay and Ernie have done and that is to mount some of your gear in a different room. Sean
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I don't know if I'm in the ballpark on this one, but I had a resonance problem with the motor on my hot-water tank system. I found these magnets at a surplus store about the size of a domino that I strategically placed on the offending ringing area and it changed the frequency enough so it is no longer a problem.
This is the first I've heard of this problem with the CAM-200s-- I'll have to go home tonight and see if mine do it, although where they are located I would never hear the heatsinks ringing, but I should hear their effect on the sound coming out of my speakers.

As for putting something over or under the heatsinks I think they get too hot to make that an option.

I would think that it would be a fairly simple matter of "wedging" a piece of appropriately size rubber (maybe a 1/4" long piece of the appropriate diameter automotive heater hose?) in between fins at their midpoint-- you'd not really adversely affect airflow or cooling area, and you should greatly reduce or eliminate ringing since you've just effectively halved the unsupported length of the fin-- this would have to alter its resonant frequency substantially.

Maybe 2 rows, one 1/3 of the way down, one 1/3 of the way up, of small pieces of appropriately size rubber (or cork) material would be more effective.

What effect this would have on the amp's sound is debatable, I guess-- although I can't see how eliminating a resonance there that's being excited by room sound would be anything but a positive for sound quality.
Goldmund understands and addresses this problem..

http://www.goldmund.com/old/Millennium/mechanics.html

Unfortunately, finding someone to make a heat sink clamp out of brass or aluminum ain't gonna be cheap 'n easy.
Pm: It's not a matter of whether the change is good or bad, but that it DOES change. As such, the sound that you are used to and may have worked hard to achieve can be altered for better or worse.

Gs: Thanks for the link to Goldman's solution for this problem. Like i said, it ain't pretty or simple : ) Sean
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