Originally Posted by tomb
With respect, how many samples is that? Microphonics vary with the tube. Some can pick up vibrations and reflect them tamely, others can thump a speaker cone to full excursion. One tube might only react when you thump it with your finger directly, others start ringing when you exhale. A few of us tube-lovers in DIY have asked questions about subminiature tubes for years, but the inherent microphonics always ended the pursuit. Tube microphonics were always something to avoid - or at least begrudgingly tolerate only in certain scenarios (like they're $750/pair?). Yet, you're going so far as to suggest that they may add to the harmony!?
You seem to be shifting the argument. Your argument was that these tubes would keeping vibrating for minutes on end. I responded with evidence contrary to that.
In regards to your "number of samples" counterargument: In my experience, the microphonics of a tube, while they may vary with each individual tube, are the pretty much the same among each model (with the same plate structure.) For example, the KR PX4 I mentioned before is a highly microphonic tube. You tap on the glass, you are going to hear that! The EML 45 mesh is amazingly resilient and non-microphonic. I haven't heard KR PX4s which were less microphonic than others, nor EML 45 meshes which were microphonic, unless they were defective. To my knowledge, Raytheon hasn't made versions of the CV6088 with differing plate structures.
The ringing (sort of like a the ringing of bell which then decays over time) usually happens upon two scenarios: when flipping the on/off switch; and when plugging in headphones. Both of these actions physically shock the tubes more than any other action - it's the shock of the switch snapping from one position to another, and the phono jack snapping into the contacts. After this, it's extremely difficult to get the tubes to ring or even present deleterious effects for any extended (a few seconds) period of time. I could tap on the chassis, jump up and down on the floor (the kids do that for me in the house), smack on my desk, etc. Is it more sensitive than most other tube amps I've dealt with? Yes? Is it something I can live with? Absolutely for $119. Should the Vali be used as DJ's headamp at a nightclub? Probably not.
While I have been enamored with the sound quality of the Vali, I've also been extremely forthright of its negatives: tube microphonics, 8 ohm output impedance (soft bass, not the best control), and noise floor (not good with IEMs, Grados, AT, etc.).
Finally, I don't really know exactly what you are getting at concerning your own aborted or failed forays into sub-miniature tube DIY amps. As an MOT, you should at least have the grace to give Schiit, another MOT, the benefit of the doubt that they know what they are doing, considering that you don't even have the amp in your hands.
Edited by purrin - 10/14/13 at 8:19am