Servo Controlled Arm

Rotarius...I think you are talking about the vertical "Biotracing" servo, which is quite separate from the linear tracking arm. Sony made pivoting Biotracer arms also.

By the way, I made a typo in my last posting. The spec tracking angle error is 0.05 degrees, not 0.5.

The Biotracer arm tracks very warped LPs with not the slightest problem. (That's why). If you lift the arm manually is has a strange "limp noodle" feel to it. The downforce remains constant dispite movement of the arm up and down as with a warped record. The downforce, VTF, is applied electronicly, so it can be tweeked while a record is playing. The arm itself is mass balanced (no downforce) and this minimizes sensitivity to vibration.

This time is about servo quasi-tangent arm. I think getting rid of anti-skating force on a linear tracking servo arm is at least ONE advantage over the conventional 9" pivot arm. It's not geometrically perfect but the tracking error is still smaller than a 9" arm. It's not a gimmick if executed right. I agree with Kirkus that the problem sometimes it's not the servo but the tonearm itself. I have a Pioneer PL-L1000 that uses a linear motor, like a mag-lev train, to glide and match the dynamic pivot movement of the arm, ie, it moves left AND right(!!), but the roller bearing quality is not on par with the motion and it's just not smooth and quiet enough, perhaps implementing with air bearing would do the trick but then again, one would compel to just simply use a conventional PASSIVE air bearing arm. I prefer the old Rabco way and simply move one direction and calculation the amount of offset and just let it roll. The Yamaha PX2 is quite successful in this regard and it sounds good. The Goldmund T3 is just a glorified Rabco, really.

I would like to see someone to come up with a servo gliding arm base so the user can mount the tonearm of his/her choice - perhaps attaching some sensors to the counterweight, arm-tube, or even at the cartridge position, for the servo system to detect the offset. This way the audiophile can use their favorite tonearm AND turntable. It will be a neat accessory. Gimmick? Maybe, but I bet it's fun. :-)

No gimmick as low tracking can attest add virtually no distortion due to precision dipersion an u have an arm that simulates cutting lathe for the master stamper

Hiho...An important detail about the Sony linear tracking servo is that it does not move in and out, as you suggested. It only moves in. (Unless you pick up the arm). This is because the servo only modifies the RATE of movement, which is always in. Because of this feature, bearing friction (which is very low) does not result in jerky motion. (In technical circles this is called stiction). Finally, with a servo, friction, as long as it is constant and especially doesn't change direction, is not very important. The purpose of the servo is to create a virtual frictionless bearing.

Eldartford, I was mainly referring and complaining about the Pioneer PL-L1000 servo arm that it uses a linear motor and it moves laterally BOTH directions, ie, left AND right. Almost like a air-bearing arm, hence the tendency to jerky motion on eccentric records. Pioneer is the only manufacturer I can think of that did something like this. It works great in theory but it puts a lot of demand on quality of the roller bearing. It certainly is fun to operate though. Yes, I still prefer the Sony, Yamaha, Technics, Rabco, or Goldmund approach. Thanks for the comment.