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Tubes and vibration - Atma-sphere MA-1

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I wonder, have anyone experimented with tube damping with Atma amps, especially, the MA monoblocs?

I am concerned that small errors due to vibration (e g airborne vibration) in each of the output tubes, times 14 output tubes per channel, amount to distortion. I have a small OTL desktop amp with one driver and one output tube only, sounding amazingly clear (Audiotailor Jade). In my MA-1 amps, the driver tubes sit very tight, but the output tubes are loosely fastened and rattle easily.

To test, I made two wire rectangles from clothes hangers, and fastened them to the top of the output tubes with small balls of blutac, damping the structure a bit more with balls in between the tubes.

Results - only first impression so far, but yes, perhaps some benefits. More coherence? I will keep them for more testing. In my notes: drums and cymbals are better separated, better treble, bass also? Perhaps some darkening of sound and detrimental effects...

Special tube damping is part of some recent costly designs (like the Einstein The Tube mk2, said to sound better than mk1 because of it). But if cheap tweaks work, why not?

Perhaps other tube amp owners have tried similar things?
Note, I have tried ordinary tube dampers, like Herbie's on some of the output tubes, without much difference (have not tried on all 28 tubes though). If the socket sits loosely, damping a bit from above may be a better idea.
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o_holter
atmasphere's avatar
atmasphere
12,088 posts
 
The sockets on the MA-1 and all our amps are supposed to let the tubes wiggle a bit. Any good tube socket should do this to avoid shortening the life of the tube.

The contacts are tin-plated. Tin, like gold, does not corrode easily or quickly, and it is a lot harder so the socket can last for decades as a result.
o_holter OP
980 posts
 
Thanks Atmasphere. This fits with my experience. The sockets are loose for a reason ("let the tube run free"). My testing shows that this works well. What remains to be seen is if a little bit of top damping makes it work even better.
bombaywalla's avatar
bombaywalla
1,958 posts
 
if you search the archives here, you'll see that several people have tried damping the tubes. Note that, from these discussions, it is important where along the length of the tube you damp - damping at the top or middle or bottom seems to have different effects. Got to play with it some w.r.t. your specific situation. FWIW.
geoffkait's avatar
geoffkait
23,365 posts
 
For Sylvania 6SN7GTs, bad boys, I find that two Herbies dampers are better than one, one on the glass about 1/3 of the way up the glass, the other on the base. Yabba dabba doo!
o_holter OP
980 posts
 
The frame I am experimenting with is easy for anyone to make, use a metal clothes hanger. I like cheap tweaks, sometimes they work. Not yet sure, in this case. Version 1 had the frame resting direct on the top of the tubes with blutac. After two days, the blutac did not feel very good, to my finger tips, and the mod did not sound so good. Over-heating I think. Half-baked. I was lucky to find some small furniture polyester dots around the house, I am now trying a version two with these below the blutac. The frame gives a lighter touch to the tubes. Not sure yet, how it sounds, but my family tends to take up the listener position - usually a good sign.
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