Nude Turntable Project

I currently have a L07d in a thousand pieces. It uses extensive complex shielding around the motors many parts. Quite necessary I think, since the coils are close to the upper platter surface and are oriented vertically, focusing their flux up and down as opposed to horizontally on some other designs.

Chris, the increase in flux strength on the SP10 MK2 when stopped is due to the brake solenoid. Powered at stop, off when running.
I don't bother with the brake at all, using the EM braking of the motor itself to pull down the platters speed at stop.

Chris, the increase in flux strength on the SP10 MK2 when stopped is due to the brake solenoid. Powered at stop, off when running.

two comments Richard

1) You confirmed that this app on my phone actually works. this is kind of cool.
2) I'm impressed with your findings.

I currently have an L07d in a thousand pieces.

I look forward to reading about how you fit an ET2 on that. :^)

But Boy, would I really like for someone like you to get yours hands on a thread drive design TT - NOT - a belt drive design that has been converted to thread.

I would love to read your impressions ...

Cheers

09-18-13: Ct0517
I am however surprised at Dovers comment.

I dont think it is ideal to have electromagnetic fields floating around the cartridge, irrespective of what type of TT is used.

I mean considering he uses a Dynavector tonearm and preferred ET2 Magnetic damping. :^)

Ct0517 - your comments are incorrect.
Though I own a Dynavector arm I have not used it for a long time. It is handily outclassed by my Fidelity FR64S, Naim Aro and Eminent Technology ET2 arms.
Please refer to my post in your ET2 thread...

05-16-13: Dover
By the way I still own a Dynavector 501 which has a very high horizontal effective mass, and whilst the bass is quite punchy, the musical timing, soundstaging, and resolution is well down on both my Naim Aro and Fidelity Research FR64S ( yes I own 2 of these as well ).

Another correction:
Very minimal magnetic damping is used on my ET2, none on the Denon 103 set up, and it is well away from the cartridge and cable. This too was explained in your ET2 thread.

03-03-13: Dover
The configuration I use is:
Decoupled counterweight in the horizontal mode ( spring bypassed )
Lightened tonearm
Minimal magnetic dampening

09-19-13: Ct0517
But Boy, would I really like for someone like you to get yours hands on a thread drive design TT - NOT - a belt drive design that has been converted to thread.
I would love to read your impressions ...

I agree, it is folly to convert a belt drive to thread drive, unless all the engineering principles on motor selection, pulley design and platter/bearing design have been revisited and are clearly understood. For example, the optimum pulley for a thread drive will have quite a different profile than that of a belt, as well as the motor design, power delivery and platter mass. An example of this is the Verdier, where the motor is not strong, and addressing this should be a prerequisite before converting to thread drive.
It is quite an ask to go from tinkering around with DD turntables to designing a thread drive. A thorough understanding of engineering principles would be a prerequisite. I would recommend you search on Dertonams posts on thread drive in this forum for authoritative and informed analysis of thread drive principles. Dertonam has had a wealth of experience with the Micro Seiki thread drive TT’s that were designed specifically for thread drive from the outset, as is the Final Audio Parthenon thread drive TT.

Dover, Funny you say that about "converting" the Verdier to thread drive. Nearly all, if not actually all, the Verdiers I have ever seen have been using thread drive. I actually thought it was "stock". One well known emporium near me that sells Verdier places the motor about 3 feet away from the platter and uses a thread drive. I've often wondered how the heck they can keep the thread from slipping down the smooth sides of the platter.

Richard, You voiced my own thoughts on the pitfall of a coreless motor; the orientation of the magnet and coils is at 90 degrees to that of a conventional motor, and this would result in max field strength in the vertical direction. Plus, the coreless motor is very close to the underside of the platter, much closer to the platter than a conventional motor in a Technics or other similar DD. I've noted that the L07D motor is a completely discrete unit, sealed in a casing shaped like a movie version of a flying saucer. Do you think the casing is made of mu metal or something with similar shielding properties? If so, why do we perceive that adding another shield under the platter mat makes a further improvement?