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                  Posted by Romy the Cat on 
06-23-2011
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                   fiogf49gjkf0d A few years ago somebody, I think it was “drdna” from California, told that he has a habit to listen the mechanical noise of the tube hold the tube at his ear by hitting the balloon of the tube. I did not exactly acknowledge it at that time as it was not my experience. I do not use the tube that have some after-shake or any long vibration in the tube guts. When I get a new tube I shake and ping it and it I hear anything that is bit off the bitten path then I just put the tube in the box with faulty tubes and do not use it. 
  However, I have discovered recently the there is more to it.  Even the tube that I pass as acceptable still have a minor Shaky differences and to my surprise I learned how to hear that difference from the loudspeakers. So, if you use tube amps or multi-amping then make sure that the tubes from right and left on the identical channels of your multi-amps do have the same shaky residue. It means the MF from R and L or the Fundamental channels from right and left must have the same echo in the glass and to have the same decay in response to mechanical vibrations. 
  Rgs, Romy the Cat
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