Amp heat sinks are ringing

There are a couple of alternatives that I have used succesfully:
1- Use small strips of bycicle inner tube less than 1/2 in wide rolled up to adequate thickness and push them between adjacent fins down to close to the fin base (shoot for this dimension when you roll the strips not the outside gap between fins). If you choose to do this in the lower part of thew vertical fin they'll be hardly noticed with several advantages, it´s a reversible tweak, tube is black as the fins are if needed can be done at middle height, add more etc. The effect on convection is minimal and you can kill the vibes.....
2- Use a small wire or better a small aluminum piece and adhere it to the fins with a hot melt adhesive gun in the underneath the lower portion of fins.
3- You can also bridge the fins with the holt melt adhesive and decrease the ringing acordingly.

Some options are far more effective than others and easier to implement depending on how careful you are the other too can be used but there's more potential problems So weight the options and the compromises you might get into.
I prefer the first one since it´s easy and totally reversible.
Have fun and kill the ringing.

Got it Sean-- but many of these fixes are easily reversable so I think we should plunge on in and see what happens- at least that's what I'm going to do.

Didn't read the whole thread -did anyone suggest using spring-type wooden clothes pins? Clamp the suckers ON!

My Forte 4a amp has singing fins. I use stiff slivers of rubber at varying spots throughout the fins to dampen the ringing. the total area of the slivers is only a thousandth of the area of the fins. Bulky things to dampen the fins on a hot baby like my Forte would be bad. The 20 or so rubber slivers I use are 1/4 inch square and about 3/4 inch long are fine, I carved them from big chemical industry bottle stoppers.

Perhaps someone suggested this and I just missed it.

The easiest thing to try first is just apply one continuous strand of electrical tape across edges of the fins connect them via the tape, which changes their ability to vibrate. You may have to run more than one layer, but if your fins are black and you use black tape, the fix is almost invisible to the eye (and cheap too).

I thought this was a fairly common tweak, but maybe not.