Vintage DD turntables. Are we living dangerously?

Hello Lewm

This one is the one I just finished on Saturday, this is one amazing table. Total weight with the Steve Blinn  large Isopeds, (highly recommended btw) is 88 Lbs 

This plinth is also available for the Mk2, below is one that I recently delivered to a customer, this one had the Stillpoints Ultra 6 for footers, also highly recommended but more than 3 times the cost of the Steve Blinn Isopeds

https://systems.audiogon.com/systems/4909

The Victor is a work in progress :-)  have not had the time to look at it for the past week or so - have you got yours up and running, if so how do you like it ?

Good Listening



Peter

@lewm while the first sp10 released in 1969 the SP20 released in 1976

This is what i have about Technics SP-20 from this source:
forgive me for google translate from Japanese:

And high performance at that take advantage of the development know-how of the SP-10mkII, Quartz phase-locked control DD turntable. Starting torque 1.5kg · cm, a large turntable of its own weight 2.5kg (inertial mass 345kg · cm2), and to rotate at a constant speed in a quarter rotation from the start. Due to the large starting torque and powerful magnetic circuit, there is no change in the rotational speed using 150 pieces of the tone arm of the needle pressure 2g. In addition, it is also possible to use a cleaner during a performance. With pure electronic brake to provide users with a smooth stop of the turntable. It has adopted a strobe LED illumination by fringes of Article a row. Finish and has prevented the surface change and wrinkle finish was special surface treatment of the aluminum die-casting.


TECHNICS SP20 PRICE: 60,000 yen (1976）

Driving System : Servo Controlled Direct Drive

Speed : 33-1/3 and 45 rpm

Platter : Aluminum diecast 32cm, weight 2.5 kg.

Starting torque Characteristic : 1.5kg × cm // Less than 0.7 （90゜） second to reach normal speed (33-1/3 rpm).

Load fluctuation : 1.5kg x cm within 0％

Rotation speed deviation : ±0.002％

Wow & Flutter : Less than 0.025%（JIS C5521）wrms.

S/N Ratio : 60dB（IEC17B） // 73dB（DIN45539B）

Power Consumption : 4W

Inertial mass : 345k × cm2

Outline Dimensions : 368.5 × 99 × 368.5mm

Weight : 8.0kg

I assume this is not as good as SP10 MK2 for sure, but must be better than old classic SP10 with different (older) platter design etc.

Lew if you’re not familiar with gun metal CU-500 mat from Micro Seiki i’m pretty sure you know at least their CU-180. However the CU-500 is thicker and heavier (2.7 kg) and very rare along with their super heavy gun metal record clamp Misco Seiki ST-20 (not as easy to find as Micro Seiki ST-10).

I don’t have any pictures of my stuff on audiogon, but this is picture of my own Misco Seiki CU-500 to check in high resolution on SP10mk2. And this is another view on the same CU-500 on the same deck.

And old picture of my teak wood plinth for SP10 with EPA-100 and Technics EPC-100c MK3 cartridge retipped by AXEL in Germany (curently for sale or trade btw:).

2.7 kg!!!!!!  That is nearly doubling the weight of the entire platter of an SP10 Mk2.  I would never do that to any DD turntable.  You could probably get away with it on a Mk3, because the base platter weighs 22 lbs to start with.  The servo is tuned to the rotational mass of the platter. You may well have enough torque to get that much extra mass moving, but you are probably losing something in terms of performance.  Perhaps Peter and JP can chime in on this subject.  Lots of modern day users of vintage DD's do these things. Keep in mind that M-S made the mat for their belt-drive turntables. In any case, I won't be looking for a CU-500 for my Victor.

The SP20 sounds like an economy version of SP10 Mk2.  You sacrifice 78 rpm, probably some electronic sophistication, and the cost of an outboard chassis, to save some cost.  I'm sure it's excellent.

Forgot to say that my TT101 is running but not "up and running". Time got away from me this weekend, and I have yet to mount a cartridge. I did install the chassis into the QL10 plinth, which I have modified extensively with metal arm board and metal re-enforcements underneath the MDF stock plinth, to add mass and structural rigidity, and constrained layer dampening.

Has anyone unearthed any data on the Victor UA7045 tonearm, particularly its effective mass?  I have an FR64S mounted on the Victor plinth, but I might want to go back to the UA7045, if it would be a better match for a higher compliance cartridge than is the FR64S.