Nude Turntable Project

Halcro,

09-12-13: Halcro
And here is the equally famous Takai Lab Final VTT-1 belt-drive turntable similar to Dover's.....although he has the Parthenon model I seem to recall which is quite different to this one?

The Final in the picture is missing most of the TT. It is a VTT1 Platter & bearing with non standard Lead Console plinth, and a Pioneer DC motor drive. It is missing the original SPZ plinth and it is also missing the original sine & cosine wave regenerated power supply and original motor.
Here's an early Final VTT1 with the SPZ plinth.
http://www.hifido.co.jp/KWfinal/G0301/E/0-10/C09-43580-46106-00/
In my VTT1 the wine/cosine generator is separate from the motor and uses a separate power amplifier for providing motor drive.
The Takai/Final Labs preceded both the Melcos and the big micro's by 7-8 years. The Melco's are interesting - they use embedded titanium in the bearing assembly, and the thrust pad is mounted on a spring designed specifically to the platter mass. The platter uses the Okubo mass formula to obtain equilibrium and minimise bearing "friction".
The Takai/Final Labs have an inverted bearing, placing the platter centre of gravity well below the bearing point, whereas the Melcos/Micro use the conventional bearing. The Takai/Final Labs also use sine/cosine wave generated power supplies for the AC motors. The Melco's & Micro's are less sophisticated in this area.

Is no one interested in the magnetic fields concentrated at the normal arc of the cartridge? It would be helpful and interesting if someone with a smartphone would install the Tesla app and repeat my experiment.

Is this a problem? Does it effect all DD turntables?

I have ordered mu-metal sheets to try and redirect the magnetism away from this area. More on that in a week or so.

Gary

according to this, it is a problem, Aigenga. I believe Lewm investigated these issues with his Kenwood.

Sorry I don't have a smart phone but next time friends come over I'll have them do it.

The symptoms of rfi and emi contamination that site articulates are certainly troubling. I don't detect them in my set up, but I suppose along each of the dimensions things could be better--so who knows. As I noted above, I stuck some pieces of TI Shield underneath my subplatter right above the motor cover. Perhaps that is doing me some good? And if I used a heavy platter mat I would use the shield directly beneath it--but the boston audio mat 2 wasn't heavy enough to flatten the piece I cut. I think the mu metal is thinner.

What does the app actually detect, EMI or "magnetic fields"? Those are two different phenomena. I would expect it detects EMI. I don't think this is endemic to every single DD turntable ever made; I would expect it is something to think about on a case by case basis with any particular DD. However, as Banquo mentioned, the L07D cognoscenti recommend implementing a shield between its motor and the platter. It seems to me that Kenwood already did that: the platter "mat" is actually a 5-lb piece of quarter-inch-thick stainless steel, which while not being a perfectly efficient shield, does act as a shield. Nevertheless, I did buy a piece of TI Shield from M Percy. I cut it in the shape of an LP and tucked it in under the stainless steel platter mat, so it does not show. I then was able to imagine that it made an improvement; I don't trust such uncontrolled observations when made by the guy who did the work and spent the money (me), but there you have it. One could do the same or similar for the TT101 or any other DD. A copper platter mat would do some good as an alternative. The SP10 Mk3 has a massive piece of bronze or brass in its surface, which probably affords some shielding. Unfortunately, last time I looked on M Percy's website, there is a notation to the effect that TI Shield is No Longer Available. I don't know whether that means it is out of production or only no longer sold by Percy. He does also sell ERS cloth, which could be made to do the job.

Note that any shield must be grounded to be fully effective. I am assuming that, since the TI Shield on my L07D is fully in contact with both the base platter and the SS mat, and since they are in continuity with the bearing, my shield is grounded. (TI Shield has layers of copper on both sides; it is quite conductive. Be careful.)

The app measures micro tesla or mili gauss - both seem to be measures of magnetic fields. If I said that I know much more than that I would be lying.

I don't yet know if I will cover the motor area - leaving ventilation space or make the mu metal sheets part of my mat, one way or the other.

Gary