Spindle oil

Guys...I guess you still don't "get" the concept behind the Sony arm. Perhaps my explanation was not the best.

The gist of the thing is that the Sony arm IS A PIVOTED ONE. What moves with the linear motion servo is the pivot point. Even if the servo were to "cog" (which it doesn't for reasons I have explained) this would only cause the arm angle (tracking angle) to vary by some tiny amount, at a frequency too low for any sonic effect to be audible. There are no sideways forces on the stylus from the servo.

Herman...perhaps it would help if I drew an analogy to driving a car in steady moving traffic on the interstate. You press the accelerator to a certain point which moves you along with the traffic. Sometimes you ease up a bit, or press down a bit so as to vary the speed according to local conditions. If you are a good driver (servo) these corrections are so gradual that your passengers never notice. In similar manner, the Sony arm smoothly varies the pivot point movement speed, but it never stops or reverses direction, which is what I think you mean by cogging. Because the arm is always moving in the same direction, at nearly constant speed, friction direction reversals, which can destabilize to fine control servo, do not happen.

Sean...The arm tracking is a completely separate servo. Actually, If I remember right the TT has five (count em!) microprocessors. Platter motor control, Fast arm movement, Fine arm movement (while playing the record), vertical arm control (biotracer), and one more to run the show.

I'm a terrible driver

El: I know how the Sony arm works and understand how it is allowed to pivot at the rear i.e. it isn't "anchored" at the rear like the older HK / Rabco motor driven designs. Having said that, even the HK / Rabco has enough "slop" in the arm assembly to allow a certain amount of lee-way should sidewall thrust come into play.

As such, i was trying to keep the discussion somewhat "universal" in scope and not just concentrate on that one specific product. There were many other mechanically driven linear trackers out there and that is what i was talking about. After all, the comment pertaining to "why aren't these designs more common in the industry now if they were so good then" was previously used. I was trying to respond to that and at the same time, keep things current with the comments being made about your Sony. Hard to be both specific and general at the same time without some form of confusion arrising : )

Herman: Maybe the Bose servo-suspension is what you need in your car : ) Sean
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Sean...By the way, that Bose writeup on active suspension reads as if Bose invented it. Interesting reading, but typical Bose propaganda. Many people have worked on active suspension over at least four decades. GE was doing it when I went to work with them in 1961.

Bose may not have invented it, but maybe they'll be the first to impliment it in a manner that is both effective and user friendly. After all, with all of the profit margin that they make on their plastic products using the lowest grade materials, they can surely afford to invest in quite a bit of R&D. It's obvious that they aren't re-investing the funds that they make off of audio into improving their audio products, so why not shovel it into another line of products all-together? Sean
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