2. amps-preamps
  3. 1138726066

Tubes and microphonics

I want to know when microphonics affect the sound.
I have a Sonic Frontiers Line 2SE Preamplifier. I tried many tubes like Valvo, Siemens, Reflector 6H23NEB.
Recently I bought two matched pair of Amperex 6922PQ White Label Made in USA. I think that the Amperex are better than the others, but I could see that they are less silent.
When I knock the cover of the preamplifier I can hear the knock clearly in the speakers. That not happen with the others tubes. The 6H23NEB are the most silents.
I think that Amperex have more gain than the others. But I don´t know when that is critical to the sound.
Please let me know your experience with your tubes and preamplifiers.
Thanks,
Pablo
elduende14

Showing 5 responses by jax2

jax2
3,031 posts
 
Pablo - the 6922/E88CC family are very microphonic, as you probably know. You may want to try some tube dampers to help out with that. I've used Herbie's and Mapleshade and either works very well. Tubes in preamps are usually very sensitive to vibrations and will amplify them (as they are prone to) at the speakers. It's more of a surprise that you do not hear the knocking on the cover with other tubes, than it is that you would with the Amperex. Anyway, give the tube dampers a try if it is a problem. Herbies are inexpensive and effective.

Marco
jax2
3,031 posts
 
Sorry George, no experience with that specific tube that I can recall. Mostly compared the German tubes in that family. My favorites in the application I was using them in were the Siemens CCa's.

Marco
jax2
3,031 posts
 
George - Unfortunately, yes, they are quite expensive and sometimes counterfitted or sold in less than desirable condition for large coin. If you go that route definitely go with a reputable resource. Expect to pay $75-150/tube (crazy!). Alternatively, in current production (or NOS if you like) I'd give a try to the Russian Rocket tube, I think they are 6H30 and are drop-in for most 6922 applications, but take care in which variety of that tube you use. I think BAT uses them in their gear. Worthy of a listen and much cheaper than NOS. YMMV and check on the application with your specific piece of gear.

Marco
jax2
3,031 posts
 
I could be wrong but, I don't think the 6H30s can be used as direct replacements for the 6922s without some adjustment.

You are quite right, my bad. It is a 6H23 that I was thinking of. Thanks for picking out the mistake.

Marco
jax2
3,031 posts
 
Just one clarification Pablo - The Siemens I liked best were the E88CCa. They are not the same as the E88CC. You can see the entire range of various brands and pricing here to give you some idea of the relative price range. I never heard the Valvo or Amperex, and even if I had it would have been in a different piece of gear so the differences between tubes would not correspond exactly to your experience with your SF2SE (nor, of course, would my preferences necessarily correspond with your own). I would always encourage others to roll their own and make their own judgements where these things are concerned. Just sharing my own experiences here. YMMV.

Marco
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