Doesn’t the Techdas turntable come equipped with an air suspension built into the pillars that support it? I thought it did. |
What user510 said. In addition, altering the distance between the platter bearing center and the tonearm pivot must necessarily create a speed anomaly, as the belt must stretch or contract to accommodate changes in the distance between the motor pulley and the platter, where the motor is not mounted on the suspension. |
Hanging with magnets would not be a viable option unless the magnetic field strength was meticulously matched to the total mass of the turntable. Even the weight of the LP itself would have to be considered, and you’d have to take care not to rest objects on the plinth surface. Otherwise you would either have the equivalent of an unsuspended state (magnets in physical contact) or the sudden equivalent of nothing holding the turntable up as it crashed to the shelf or earth. Suspending the turntable footers between opposing magnets, top and bottom, might work. |
Wolf, as you probably know better than I, if you actually play guitar, guitar amps are distortion generating machines. The distortion is intentional. This is one reason why overstressed tubes are preferred by the cognoscenti in guitar amplification, unless you disagree. One form that that distortion takes is due to the microphonics of the tubes adding to the other distortion generating characteristics of the circuit. Don’t you think? Speaking for myself, when I hear a really prominent electronic guitar solo, I think I can hear components of the distortion that are due to tube microphonics or are very characteristic of distortion caused by microphonics. I just don’t think there is much effort to avoid microphonics from guitar amplifiers in general.
Furthermore, I and others have been saying all along that microphonics are more or less of a problem with certain tube types and with tubes used in circuit in different ways. Hi gain tubes that have a large glass envelope tend to have the most problems with microphonics. Small nine pin miniature tubes like mijostyn‘s 6922s are perhaps a bit less prone to microphonics, but Atma-sphere seems to disagree. Tubes used as cathode followers, i.e., to convert voltage into current and add no gain are less prone to microphonics. If one cannot hear a certain kind of distortion or noise in one’s audio system, that does not mean it is totally absent. It just means you can’t hear it. Which often is good enough. |
Use, 6SL7 is even more microphonic than 6SN7. But not as irreplaceable if ultimate sonics are the goal. Gain notwithstanding. |
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. |
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. |
I apologize for being too harsh, Mijo. Was trying for humor. By the way, my OTL Atma-sphere amps originally used the high current Russian triodes (6C33C) designed for use in their jet fighters on board radar. This was deemed advisable because tubes are immune to nuclear blast emissions whereas SS is not. The US countered with an even higher current triode, the 7241, which until not so long ago was used in our own radar installations, at Andrew’s Air Force Base in MD, for one example. It may still be in use, for all I know. Anyway a few years ago I converted my amplifiers from the 6C 33C to the 7241. They are way more expensive and harder to find, but the sonic benefits seem worth the effort and expense. |
Mijo, Mijo, Mijo. You consistently mistake your own observations and opinions for science and facts. Tubes are microphonic, some more than others, and most tube gear does benefit from isolation and dampening. Not necessarily with spring suspension. Like I said, some guys even isolate, suspend, or dampen their solid-state gear, although the rationale for that is perhaps less obvious. If you ever looked inside a Halcro preamplifier, for one example, you would see that the entire printed circuit board has been sprayed with a rubbery coating to dampen vibration of the individual components. And that is solid state to the utmost. |
Mijo, I am rather surprised at your attitude toward isolating "electronics". Perhaps you eschew the use of tube equipment as absolutely as you prefer spring suspended turntables, but anyone who does use tube equipment will know full well that tubes are sensitive to vibration, because all tubes are at least to some degree microphonic, and many types, especially some of those with larger glass envelopes, can be very microphonic. Some of the more expensive tube equipment makers (e.g., Allnic) even go to the trouble of isolating tube sockets in an energy-absorbent gel. Without exception, I have found tube preamplifiers (phono and linestages) to benefit from isolation, and tubes benefit from "dampers". As to transistors, according to Wiki one of their main advantages over tubes is a lack of sensitivity to mechanical vibration. And yet, many do use expensive isolation devices, for good or ill, with transistor gear. Those persons would tell us what a huge improvement they experienced. Certainly, CD and DVD players do benefit from isolation, for obvious reasons related to the laser reading the disc.
Now, as regards the F22, in order for that airplane to fly, its piloting computer must be oriented in space at all times, so it can "know" how to maintain level flight and issue the correct commands in response to its pilot. I have no doubt that its piloting computer must be encased in some sort of module that keeps it aware of level flight and is isolated from vibrations, because, like a phonograph stylus, if it is vibrating, even though its component parts are not sensitive to vibration, it might not be able to sense how to create stable flight. Or perhaps it senses its own micro-instability and corrects for that.
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Haha on me. Thank you, thecarpathian, for correcting me. I was indeed thinking of the Tacoma bridge, not the Verrazano. Only today did I see my error. Anyway, the point of my analogy still stands, or falls.
If the Verrazano were to shake itself to death, THAT would be spectacular. |
MC, You might be correct about the cause of the bridge collapse. I mentioned it more for the sake of humor than anything else, and my guess is or was that the resonant frequency of the bridge suspension(s) and the wind velocity had something to do with it. But I certainly did not back up my remark by actually researching the cause. If you look at the famous video of the bridge shaking itself to death, it appears that the suspensions, one on each side of the bridge expanse, are resonating at different frequencies, which causes the road bed to be twisting and tilting so crazily, which eventually led to disaster. I dunno.
Anyway, we all agree that putting a turntable with a built in spring suspension on top of a spring-suspended shelf is usually not a good idea, unless the doer has a good understanding of the physics and the proper instruments to determine what might work. This is not a knock on spring suspensions per se.
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Usually it’s a very bad idea to “suspend” on springs a turntable that already has a built in suspension. So I am surprised that a few recommended adding a sprung shelf. The two suspensions will inevitably fight each other which could end up with positive feedback of vibration. Remember the Verrazano Narrows bridge collapse. |
