Servo Controlled Arm

Guys, you are barking at the wrong tree here. The JVC QL-Y3F turntable is NOT a tangential linear tracking arm. It is a pivot arm with what is called an ED(electro-dynamic)Servo arm to control damping and behavior of arm movement in using electronic means.

vinylengine.com/library/jvc/ql-y3f(DOT)shtml

Here's a blurb from The Vintage Knob site: thevintageknob.org/VICTOR/QLY7/QLY7(DOT)html

"The goal was to eliminate as much as possible the ED Servo (Electro-Dynamic) tonearm's own resonances and stray vibrations : there is no bearing (per se) but two motors which drive the arm's movements vertically and horizontally."

"Tracking force, anti-skating and Q Damping can therefore be operated from elsewhere than the tonearm's base : the minutious mechnical controls included in the tonearm of the QL-F6 were scrapped for "micro-computer" control - a very cool word in 1980!"

"VTA is adjustable with a lock on the non-electronic side of the tonearm."

JVC was an innovative company and their turntables are excellent quality. Their more conventional tonearms that came with their QL series turntables are true sleepers.

By the way, I am not a fan of linear tracking servo arm either but they still have merits even if they can't keep tangency through out but the elimination of anti-skating force and it has its sonic merit and the evenness and consistency of sound through out the entire record side is not to be sneered at. Of course you can argue it still exhibits miniscule force. Playing a record in the real world situation very often negates absolute tangency so any idea or innovation to help the needle navigates this dynamic journey is welcome.

But back to Drewmbl's question as to why don't we see more servo arms in the way JVC implement, I don't have an answer. But I suspect cost and complication is the reason. JVC was a big corporation that could afford to spend millions on R&D on such technology but certainly not for the now niche market of tonearm, which is a cottage industry now. A lot of Japanese turntables got criticized because because they are direct drive and many features automatic mechanism which to the audiophile community that's losing "street cred" right there. Many never even bother to listen to some of these gems.

One thing I don't understand is that why can't more people come up with a passive tangent arm, not the servo kind, without using the damn air-bearing. I know Clearaudio is the lone manufacturer here but surely there's gotta be another way of dragging the needle across the record without using a pivot arm. I saw an experimental turntable once that uses water to flow the arm as bearing. Hmm....

Kirkus, thank you for your insightful comment. Very informative on the shortcomings of these servo arms regarding the cartridge mass interacting with the arm mechanism.

You are also correct on the linear tracking servo arms like the Rabco and Goldmund. I used to object to such design for the same reasons the above members mentioned but I have since revised my thoughts on them. Doing away with anti-skating and tracking consistency across the entire side of a record and less stress and wear on the cartridge cantilever are all positive features to me. After all Goldmund is planning to release their $30,000 Reference 2 table with a linear tracking servo arm, T-8, a T-3 arm on steroid.

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.

I just received a JVC QL-Y5F today and the servo controlled tonearm does work! It sound very good and very stable and no problem tracking warp record. Now, I really wonder why people don't use more of such design...

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. :-)

Eldartford, thanks for the comment and explanation. I understand the financial difficulty in such project but I just wish audiophiles are more open-minded about such devices and not write it off so handily by preconceived notions. Look what happened to decades of engineering in direct-drive turntables being almost completely dismissed by audiophiles. Many esoteric turntables are made not even based on real engineering and, in fact, by someone with a band saw in their garage, while the flagship product by whole team of R&D in a electronics giant never even got noticed in The Absolute Stereophool land. It's our loss. Sometimes, I wonder what would happen to analog if CD were introduced a decade later than its original date. Think of the possibilities in vinyl playback...