How to isolate turntable from footstep shake or vibration

Mijostyn, if everything boiled down to your personal experience, the world would be a simpler place to live, for sure. Tubes ARE microphonic, regardless of my or Ralph’s opinion. FYI, you may pay extra for quiet tubes from certain vendors, but what you’re paying for is lower than average levels of electronic noise, a good idea in a phono stage, but that spec says nothing about microphonics of that particular sample, which is a separate issue not usually measured by vendors, because microphonics will vary from one installation to another, even from one tube socket to another. 9-pin miniature triodes like your 6922s have a lesser tendency to be noticeably microphonic, compared to, say, octal base triodes like 6SN7 or 6SL7, so you’ve lucked out with your unit. But know that tubes can also become more microphonic as they age. Also, since the 6922 has modest gain factor, I am guessing your phono is a hybrid design, using transistors in combination with the 6922. This is another reason you might feel immune to the problem.

If the military can make electronics that are immune to vibration so can the high end audio industry.

Yup! One of the ways the military does it is vibration mitigation solutions- for example EAR makes a bituminous based extensional damping compound that gets used in submarines. When tubes were involved they used isomeric mountings on the tubes sockets to limit vibration transmission to the tubes themselves.


BTW 6922s tend to be more microphonic than the 12Axx family of tubes since they were intended for instrumentation rather than audio. That you have a set that is so low in microphonics that you can't hear it when tapping on them is really unusual- so much that its in the realm of outright miracle.

@atmasphere,  I don't believe in miracles. ARC put tube "prophylactics" (damping rings?) on the tubes. I have no idea if this cuts "microphonics" 
@lewm , I'm not talking about hitting the tubes with a baseball bat, just light tapping. Yes the PH3-SE is a hybrid design. I think it uses a FET front end.  At some point you have to rely on experience. (and people you trust)

The next question is if tubes are microphonic how much energy or input does it take to make them sing and how does this affect sound quality. Will putting a tube phono stage on an isolation base change the degree or level of microphonics and can this be quantified. What about solid state. My preamp is digital. When I get home I'll put a wooden block on it and bang the block with a hammer to see what happens. That is way more energy transferred to the chassis than anything being transmitted by air or through it's feet. Once turntable is set up I'll do the same to the phono stage, the Oppo and the Apple mini to see what kind of noise I can generate. Next, I'll put my cell phone's volume up all the way and put it on speaker phone. Then I'll put the phone directly on each piece of equipment and I'll run a slow frequency sweep through the phone (what ever frequencies the phone will transmit). With the phone in direct contact with each unit that should transfer more energy to the unit than any system can. The the volume on my system turned all the way up we will see if we can hear anything!

ARC put tube "prophylactics" (damping rings?) on the tubes. I have no idea if this cuts "microphonics"

:) of course it does! Warren Gehl of ARC came up with that material (he also designed the Sumiko Analog Survival Kit) and it is one of the best materials I've seen for controlling microphonics in low signal tubes.

The old MFA luminescence preamplifier was one of the best sounding single-ended preamplifiers ever designed, and it used 6SN7, 6EM7,and 6SL7 tubes, all of which are octal-based triodes with large glass envelopes. I owned a luminescence that would sing if I turned the music up too loud and it was very obvious what was going on. I was able to tame them after a while. And with dampers. Sadly for those who love them as one of the best sounding small signal triodes ever built, the 6SN7 is one of the culprits for being especially microphonic. In fact, the best and most rare ones are often the most prone to microphonics. It’s a problem you live with, if you love the tube and how it sounds. Another thing to consider is that the level of microphonics for a given tube in a given circuit often is related to the signal gain developed inside the tube. I am beginning to suspect that in your AR preamplifier the 6922 is used as a cathode follower. Cathode followers develop no gain, and that may be why you are having no problem with microphonics even when tapping on the tube. Just a guess.