Newbie alert !
I read somewhere in forum itself that direct drives when correcting speed is tuned to the platter weight, i.e. whenever speed changes occur the electronics supply exact torque required to the platter. Is that true ?
Regards.
No, the Technics are a properly implemented analogue PLL.
BTW, can you give me a link to where it (incorrectly) said that please ?
Dave
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Don't forget that the MKIII HAS THE WHOLE ROTOR ASSY as an integral part of the platter and that this fact is responsible for the increase in weight over that of the MkII. That which is the platter per se appears to be the same as in the MKII.
This link gives a good overview of the various models in the range - along with other contenders. Scroll down to find the MkIII.
This link gives a good overview of the various models in the range - along with other contenders. Scroll down to find the MkIII.
Firstly, the missing link:
TECHNICS SP-10 : SP-10Mk2 : SP-10Mk3 Direct Drive DD Professional Studio Turntables Panasonic
@ DaveC
Just looking at the pics it seems that the rotor is a very substantial and heavy affair. If you measure the thickness of the platters from both models there may be some variation and that may (partially) answer your question.
EDIT:
I see that the MkIII platter has a copper core. That will account for quite a bit of extra weight.
SP 10 Mk III
"Technics went even a step further in designing the perfect turntable. In 1981 the SP-10 Mk 3 was introduced. It had a platter consisting of a copper alloy inner section and an aluminum outer part, weighing a mere 10 kg = 22 lb. and the complex electronic circuitry to regulate the speeds and constancy of the rotation of this heavy platter. The total unit itself weighs 18 kg (=40 lb.). This machine was not sold in great quantities because digital media were emerging on the horizon and few owners of an SP-10 mk2 saw the need of switching to this newer version of turntable. In hindsight they may regret it."
TECHNICS SP-10 : SP-10Mk2 : SP-10Mk3 Direct Drive DD Professional Studio Turntables Panasonic
@ DaveC
Just looking at the pics it seems that the rotor is a very substantial and heavy affair. If you measure the thickness of the platters from both models there may be some variation and that may (partially) answer your question.
EDIT:
I see that the MkIII platter has a copper core. That will account for quite a bit of extra weight.
SP 10 Mk III
"Technics went even a step further in designing the perfect turntable. In 1981 the SP-10 Mk 3 was introduced. It had a platter consisting of a copper alloy inner section and an aluminum outer part, weighing a mere 10 kg = 22 lb. and the complex electronic circuitry to regulate the speeds and constancy of the rotation of this heavy platter. The total unit itself weighs 18 kg (=40 lb.). This machine was not sold in great quantities because digital media were emerging on the horizon and few owners of an SP-10 mk2 saw the need of switching to this newer version of turntable. In hindsight they may regret it."
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Um, yes it will, that is my point, and remember I have both on the bench here. To be honest the rotor assembly to me, is a red herring, not sure why it was mentioned
But whatever, the weights are as shown and they are the rotational weights whatever.
Dave
Dave
Thanks Dave. Here is the link #103. I have Technics Direct Drive Turntable, on which I intend to put small center weight (possibly hollow acrylic with 1mm ball bearings) and probably inside the platter a damping ring (Don't know the material). My question is being cheap turntable would this extra load require more current and eventually overburden the critical components ?
Thanks and regards.
OK, got that. Few people understand the analogue PLL mechanism of the Technics turntable, and fewer still have measured it dynamically.
However a lot of people think they do know and the internet is awash with incorrect regurgitated hearsay. Even the other link on this page got the weight of the MKII platter wrong by 20%.
And no, you will not harm your turntable at all.
How I test
AES Membership
However a lot of people think they do know and the internet is awash with incorrect regurgitated hearsay. Even the other link on this page got the weight of the MKII platter wrong by 20%.
And no, you will not harm your turntable at all.
How I test
AES Membership
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Thanks again Dave. That's comforting to know. I do attentively follow yours and others informative posts.
Just wanted to know PLL control and found this. Though I am electronically illiterate I read the articles. So one more probably silly question. I see there is a magnet in one removable part of the SP10 motor. I was wondering since coils and magnet attract/repel each other can one mechanically mod it in such a way that while the motor is running it minutely lifts itself along with the platter ? This would result in less bearing noise. The ball bearing would not leave the thrust pad though.
Just wanted to know PLL control and found this. Though I am electronically illiterate I read the articles. So one more probably silly question. I see there is a magnet in one removable part of the SP10 motor. I was wondering since coils and magnet attract/repel each other can one mechanically mod it in such a way that while the motor is running it minutely lifts itself along with the platter ? This would result in less bearing noise. The ball bearing would not leave the thrust pad though.
ClearAudio uses separate magnets to lift the platter. I was thinking about the ring magnet of SP10 and wondering if we move the position of the magnet would it lift by itself (fractionally ofcourse. Just enough to lessen the load on ball bearing) to align with the stator coils while running. If at all that is possible
Regards.
Regards.
So, I just caught up on this thread:
About the Mk2a,yes indeed proprietary chips create a vacuum (not sure if I can use the S word here), but is the motor hardware (as in design, interface, drive coils and such) the same across different SP=10 models? It seems that worst case, you could make new boards with the MkII electronics to put in a Mk2A chassis.
For that matter, you could make completely new electronics. I've got a nonfuctioning SL-1500 I've wanted to fix and/or make new electronics to drive with an ARM microcontroller. It's amazing what's possible now with cheap electronics, OTOH it's amazing what they did 45 years ago with all those three-terminal devices.
Wanting to know what's so special about this SP-10 thing, I got the MkII service manual and am looking it over. Almost all the TTL chips are flip-flop dividers to go from the quartz oscillator down to the sync/PLL/strobe frequencies, and thus easily understood. The rest of it ... I don't recall seeing this many discrete transistors in a (mostly/partly) analog circuit before. The block diagram helps a lot. It appears to use three sense coils as well as three drive coils. Has someone written a good circuit/operation description that might be available online? The service manual is actually better than I expected in this regard. I've only looked at it for a few minutes - I'll definitely study it in more detail.
About the Mk2a,yes indeed proprietary chips create a vacuum (not sure if I can use the S word here), but is the motor hardware (as in design, interface, drive coils and such) the same across different SP=10 models? It seems that worst case, you could make new boards with the MkII electronics to put in a Mk2A chassis.
For that matter, you could make completely new electronics. I've got a nonfuctioning SL-1500 I've wanted to fix and/or make new electronics to drive with an ARM microcontroller. It's amazing what's possible now with cheap electronics, OTOH it's amazing what they did 45 years ago with all those three-terminal devices.
Here's a thread where someone attempted to build a new motor control circuit for the SP10MkII. I believe some of your questions will get answered there, or in the constructor's own web pages referred to in the thread.
New Technics SP10 motor controller specification
