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Restoring and Improving A Thorens TD-124 MKII
Restoring and Improving A Thorens TD-124 MKII
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Old Today, 07:49 PM   #2671
anatech is online now anatech  Canada
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Restoring and Improving A Thorens TD-124 MKII
Are you calling the upper platter lift-off device a clutch?

I have repaired a number of TD-124 turntables over the years and keep forgetting they do not have a clutch, whereas the rest of the newer models do. My error with that mental slip. With the tight belt and idler wheel, the motor is tightly coupled to the sub-platter. Any attempt at using a clutch would have resulted in a large, beefy affair.

I do remember that at the time when the TD-124 was being marketed, most manufacturers were advertising how quickly their tables would reach playing speed - something a radio station or maybe an early DJ would benefit from. I can't remember which turntable it was, but one of them would reach 33 1/3 RPM in 1/3 of a revolution.

It took a few years before the more familiar figures for stability and rumble figures became normal, and those specs are more useful to a domestic use table might be.

As for the upper platter, what would adding mass to that be good for? Once it makes contact with the rubber pads, It "connects" to the lower platter and takes on its mass as far as the record is concerned. If you want to improve that coupling, I can see where a different connection than the rubber bumpers (for want of a better description) would work. A thin Sorbothane product might make a huge difference without adding any weight to the top platter. Just make it the same thickness as the original bumpers and you wouldn't need to change anything in the setup. Using more of them would distribute the connection and maybe even damp the upper platter more.

-Chris
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Old Today, 08:05 PM   #2672
Dilbert is online now Dilbert  Canada
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Hi Chris, I think there is confusion in that some of us call the device that disengages the upper and lower platters, a clutch.

My concern is with the cast iron lower platter impacting the VTF of cartridges with strong magnets, as the Ortofon SPU series are reputed to have.

Also, as Nigel pointed out there may be some EMF being induced as well.
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Old Today, 08:12 PM   #2673
user510 is online now user510
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Quote:
Originally Posted by anatech View Post
Are you calling the upper platter lift-off device a clutch?

I have repaired a number of TD-124 turntables over the years and keep forgetting they do not have a clutch, whereas the rest of the newer models do. My error with that mental slip. With the tight belt and idler wheel, the motor is tightly coupled to the sub-platter. Any attempt at using a clutch would have resulted in a large, beefy affair.

I do remember that at the time when the TD-124 was being marketed, most manufacturers were advertising how quickly their tables would reach playing speed - something a radio station or maybe an early DJ would benefit from. I can't remember which turntable it was, but one of them would reach 33 1/3 RPM in 1/3 of a revolution.

It took a few years before the more familiar figures for stability and rumble figures became normal, and those specs are more useful to a domestic use table might be.

As for the upper platter, what would adding mass to that be good for? Once it makes contact with the rubber pads, It "connects" to the lower platter and takes on its mass as far as the record is concerned. If you want to improve that coupling, I can see where a different connection than the rubber bumpers (for want of a better description) would work. A thin Sorbothane product might make a huge difference without adding any weight to the top platter. Just make it the same thickness as the original bumpers and you wouldn't need to change anything in the setup. Using more of them would distribute the connection and maybe even damp the upper platter more.

-Chris
The TD124 always had a clutch. It functions by lifting the upper platter up off the spinning flywheel below it and also by dropping the upper platter onto the spinning flywheel below. This function was intended to give the deck appeal to radio stations in that you had instant-on sound on que. Its sole purpose.

re: more massive upper platter and what it might be good for. One thing would be to move the phono cartridge further away from the iron platter below it, thus eliminating any electro magnetic interraction between the iron platter and the phono cartridge. Particularly moving coil cartridges, such as an SPU, which have much stronger magnets than do moving magnet and moving iron cartridges -- generally.

Another suggested benefit would be the added mass which would thus add additional force to the moment of inertia at the rim. Thus, a greater driving force.

Still another benefit would be the use of alternate materials which have lesser tendencies to ring -- and -- further isolation from any bearing and drive train noise that would otherwise find a way into the record groove. Intended result - quieter noise floor as well as lower distortion being generated at the point of pickup.

re: rubber pucks and coupling between upper and lower platter. The goal would be to -- de-couple -- the upper from the lower platters in so far as noise transfer between them is concerned. At one time I believe Jim Campbell in PA was selling a silicone puck as replacement for the original rubber pucks Thorens used on the TD124. I tried a set and thought that it worked to good effect, although the silicone pucks did not handle the wear and tear of the action and began to break up around the edges. Though they continued to function just fine, and perhaps they dropped the noise floor just barely enough to be percieved as an improvement in clarity when listening for the difference very closely.

-Steve
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Old Today, 08:30 PM   #2674
anatech is online now anatech  Canada
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Restoring and Improving A Thorens TD-124 MKII
Just a thought then.

It would seem to me that some extra distance between the lower and upper platters would be a benefit - yes?

There is a make of platter mats that is slightly tacky on one side that comes in various thicknesses. I intend to buy a couple for my newer Thorens tables where I used to use a Platter Matter. These would serve the dual purpose of spacing the platters apart for the thick ones, and decoupling the platters acoustically while also damping the top platter. An older Platter Matter could be used as an experiment, but they become hard on the top surfaces. So they will at least let you know if the thickness would be effective.

Another thought would be to have a circular steel plate stamped out and sandwich it between two platter mats. This would shield the cartridge from the lower platter. Degauss that part first and maybe also the lower platter.

-Chris
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