And a mechanism for damping the oscillation at the resonant frequency. Otherwise, the TT will constantly bounce at its resonant frequency, once excited. How does a car do without shock absorbers? This has been an issue with spring loaded TTs since the original AR was launched. The AR was actually better than some that came later, in that regard.
|
The world of modifying these vintage turntables is such a tiny one, I can only wonder why you cannot include the name(s) of these "renowned" engineers so others might benefit. And the engineer might also benefit in terms of increased earnings. In any case, the Krebs modification is worthwhile based on my listening to the Mk3 before vs after, if that interests anyone. Richard Krebs resides in New Zealand. I have never met him. He is lately known for the K3 turntable which is his build, now sold by Oswald Mills Audio for huge bucks.
|
You might want to investigate the modifications made by Richard Krebs for Technics SP10 Mk2 and Mk3. He spent a lot of time investigating the stators and how to stabilize them. I have had my own Mk3 modified according to Richard's Ideas, by a local tech who learned the procedure from Krebs himself and is one of a few persons in the USA qualified to perform the modification. The idea being that these motors have enough torque such that the stators are subject to movement in a direction opposite to that of the platter, when torque is required. This causes the servo to "read" a speed instability where there may be none, and thus a kind of oscillation is possible where the servo is calling for unnecessary speed correction. This in theory can cause an audible coloration. Unfortunately, the actual modifications are shrouded in mystery; I can only say the changes seem to involve the stators. I can also say that even though I heard no real "problem" with the Mk3 a priori, the Krebs mod really did rmake the Mk3 sound more like real music. I did hear, and have so stated in this Forum, a slight "gray-ish" coloration in the SP10 Mk2, when I owned one. I assume the Krebs mod would be beneficial to reduce or eliminate that issue in the Mk2. The good news is that the Krebs mod on the Mk2 is less expensive than on the Mk3 I am quite sure the Krebs mod(s) do not include the introduction of Panzerholz or the like.
|
If a stator bowl is what I think it is, you may as well redesign and replace the whole motor. And once you’ve done that, you need to address the function of any speed control mechanism. If you go deeply into that area, you may succeed in never having a functional turntable, as one problem leads to another.
|
Terry, no, I am not talking or thinking about a loss of high frequencies in the audible range. Suffice to say I prefer the L07D without its peripheral ring. Any adjective I choose is bound to give someone somewhere the wrong impression. Language fails us.
|
FWIW, Kenwood made a peripheral ring back in the early 80s for the L07D. If you use it, there’s a special setting on the power supply/motor control module so the servo then compensates for the added inertial mass. Yet the ring seems to slightly downgrade the SQ of the turntable. Darkens or closes in the sonics, slightly.
|
Ok, so I neglected to mention the washer. Sue me. I don’t use it with flat LPs, and again I thought the discussion was about sonic effects of weights and clamps, not record warps. But inevitably it seems headed that way. There’s only about a dozen other threads on that subject. Carry on.
|
We know, but weights and clamps typically contact only the label. What they otherwise do is push the LP into closer contact with the platter or the mat, and that’s where ideally you want delrin or graphite.
|
You don’t need a threaded spindle to use a clamp. The well regarded SOTA clamp is a simple reflex clamp that clamps the spindle and pulls itself against the label as you flip the clamping lever. It’s been around for decades. I’ve use it with 5 different TTs, none of which have a threaded spindle.
I thought we were talking about the sonic benefits of weights or clamps, not their use to flatten warps. That’s an entirely different subject.
|
These are only opinions, but yes. You need to listen for yourself. In some cases, I can imagine that one might prefer no weight or clamp.
|
Depends upon the TT drive system, whether there is potential to damage the bearing or drag on the motor. Some use what I view as ridiculously heavy weights, 500g and much more. I would stay at or below 250g, as an arbitrary rule of thumb. Clamps can be very light, because their effect depends upon a physical push provided by a threaded mount or a clamp mount, and certainly a well made clamp is putting no strain on the motor or bearing; it’s pushing the LP against the platter mat and platter. If you believe that your platter mat is an important component for dissipating energy generated at the stylus/vinyl interface (and I do), then the use of a moderate weight or clamp is justified. Very expensive, sometimes very heavy, weights made of exotic materials that make magical claims for improving sound quality, beyond any improvement one may perceive from a "sensible" weight or clamp are a manifestation of audiophilia nervosa, in my opinion. For example, Shun Mook.
|
There’s a difference between a clamp and a weight, both in weight and function.
|
