The necessity for absolute tt speed control

[Lagonda]

Would pls attribute the quote. Thank you.

Don't forget Tim, that the TT's here are all heavy platter designs where instantaneous adjustment of speed would take a very powerful motor (even more than the beast being used) and no slip or crimp of belt or drive wheel for successful implementation. Your table has no lag/ slip in drive train, and a light platter, like Mikes NVS.

 

[Mike Lavigne]

Don't forget Tim, that the TT's here are all heavy platter designs where instantaneous adjustment of speed would take a very powerful motor (even more than the beast being used) and no slip or crimp of belt or drive wheel for successful implementation. Your table has no lag/ slip in drive train, and a light platter, like Mikes NVS.

"Mike's NVS" has a 40+ pound platter, but the motor is very powerful. OTOH the motor is essentially part of the platter. you can use a wedge to keep it from starting. but......once the thing starts moving you can't casually stop it with your hand.

 

[Lagonda]

"Mike's NVS" has a 40+ pound platter, but the motor is very powerful. OTOH the motor is essentially part of the platter. you can use a wedge to keep it from starting. but......once the thing starts moving you can't casually stop it with your hand.

Is it a 40 lbs platter ? I stand corrected ! That is heavy for DD

 

[Mike Lavigne]

Is it a 40 lbs platter ? I stand corrected ! That is heavy for DD

yes it does. and it is. if you look at it closely it's a composite resin aluminum sandwich 3 inches thick and solid. Innovative Drive, the company that designed and builds the NVS, uses a resin composite for the platter that mimics vinyl for optimal synergy.

INNOVATIVE DRIVE

www.innovativedrive.com

my stainless Rockport System III Sirius platter weighed 55 pounds.

 

[Lagonda]

yes it does. and it is. if you look at it closely it's a composite resin aluminum sandwich 3 inches thick and solid.

my stainless Rockport System III Sirius platter weighed 55 pounds.

I have never seen any of them in real life.

 

[tima]

Having experimented with both, I find music reproduction superior, without speed feedback and continuous speed corrections.
Continuous speed correction is an indication of other issues not necessarily related with the motor

I can agree that continuous speed correction suggests continuous error which suggests a flaw somewhere. However continuous feedback does not imply continuous correction.

 

[ddk]

I can agree that continuous speed correction suggests continuous error which suggests a flaw somewhere. However continuous feedback does not imply continuous correction.

With dd turntables continuous feedback is continuous correction, just the nature of the beast. In simple terms feedback is used to tell the platter where to go and how fast, of course the sonic effects are somewhat different from feedback loops applied to belt drives.

david

 

[Mike Lavigne]

I can agree that continuous speed correction suggests continuous error which suggests a flaw somewhere. However continuous feedback does not imply continuous correction.

talking to Win on this subject he spoke about the idea of feedback on an 'occasional' basis to check speed. every couple of minutes to correct for drift, and the correction relatively benign, whatever that meant, but he never found that drift was an issue. so never executed any process for it. not sure if that is a typical way to do it or a new idea.

if i have not related Win's words appropriately i apologize. that is my memory.

i also recall speaking to Andy Payor about the feedback process on the Sirius III Rockport, which was sampling millions of times a second. his power supply/controller/motor was way over the top......and not real world for audio gear.....more industrial tool design real world.

 

[ddk]

talking to Win on this subject he spoke about the idea of feedback on an 'occasional' basis to check speed. every couple of minutes to correct for drift, and the correction relatively benign, whatever that meant, but he never found that drift was an issue. so never executed any process for it. not sure if that is a typical way to do it or a new idea.

if i have not related Win's words appropriately i apologize. that is my memory.

i also recall speaking to Andy Payor about the feedback process on the Sirius III Rockport, which was sampling millions of times a second.

Saskia's motor is AC Synchronous not DC, speed is adjusted with frequency, no monitoring or feedback loop needed just set and forget.

david

 

[Lagonda]

Saskia's motor is AC Synchronous not DC, speed is adjusted with frequency, no monitoring or feedback loop needed just set and forget.

david

Are you sure about that David ? I have a suspicion that it uses a Studer/Revox capstan motor, and depending on model , they are AC or DC and the early AC ones like my Studer A 80 motor are not fully synchronous , they drift a little and are normally natively regulated by a constant servo system adjusting the voltage inside a limited range with a transistor.

https://www.reeltoreel.nl/studer/Public/Products/Recording_Analog/CapstanPapers/JAES-69-17-4_AFStosberg_NewCapstanDriveConcept.pdf

 

[ddk]

Are you sure about that David ? I have a suspicion that it uses a Studer/Revox capstan motor, and depending on model , they are AC or DC and the early AC ones like my Studer A 80 motor are not fully synchronous , they drift a little and are normally natively regulated by a constant servo system adjusting the voltage inside a limited range with a transistor.

He's using a Papst motor.

david

 

[Lagonda]

He's using a Papst motor.

david

These are Pabst motors, in the 70's they stopped relying on main line frequency for speed control and used first AC motors with voltage servo feedback loop, and later DC Pabst motors that look a lot like the AC ones with electronic control instead of the earlier mechanical/ magnetically systems these later Pabst motors have more wires going into them.

 

[ddk]

These are Pabst motors, after ca 1976 they stopped relying on main line frequency for speed control and used first AC motors with voltage servo feedback loop, and later DC Pabst motors that look a lot like the AC ones with electronic control instead of the earlier mechanical/ magnetically systems these later Pabst motors have more wires going into them.

AFAIK the controller in Mike's version, Saskia 1 was frequency based Saskia 2 comes with a different controller, this one I believe does have some type of feedback and adjustment loop. Of course I could be wrong just going by a conversation I had with Win a few years ago.

david

 

[Lagonda]

AFAIK the controller in Mike's version, Saskia 1 was frequency based Saskia 2 comes with a different controller, this one I believe does have some type of feedback and adjustment loop. Of course I could be wrong just going by a conversation I had with Win a few years ago.

david

I think the Australien developer of that 3 phase controller is a WBF member, and has posted something here about it recently, i will try to find it.

 

[spiritofmusic]

From what I read, he designed the motor in isolation from the rest of the TT. He never got a chance to test it in situ with the rest of Saskia I.

 

[Lagonda]

It looks like the guy from Australia developed the first 3 phase controller, the description of the motor and its speed look suspiciously like the one from my earlier post, but he says it is synchronous. So you where right.

Saskia model two

enjoying the Saskia model two/Tosca/Etsuro Gold tonight. listening to some new vinyl. 'Circles', Mac Miller. https://www.amazon.com/Circles-2LP-Clear-Vinyl-Miller/dp/B083P8RCQX/ref=tmm_vnl_swatch_0?_encoding=UTF8&qid=&sr= i'm not normally a rap sort of person, but this is maybe a crossover...

www.whatsbestforum.com

 

[Mike Lavigne]

AFAIK the controller in Mike's version, Saskia 1 was frequency based Saskia 2 comes with a different controller, this one I believe does have some type of feedback and adjustment loop. Of course I could be wrong just going by a conversation I had with Win a few years ago.

david

my understanding is my model two controller has the ability to use feedback in some way, but it's not operational. it's definitely different than the earlier version.

 

[tima]

With dd turntables continuous feedback is continuous correction, just the nature of the beast. In simple terms feedback is used to tell the platter where to go and how fast, of course the sonic effects are somewhat different from feedback loops applied to belt drives.

Are you saying feedback drives voltage? If speed is correct does that count as correction?

 

[microstrip]

These are Pabst motors, in the 70's they stopped relying on main line frequency for speed control and used first AC motors with voltage servo feedback loop, and later DC Pabst motors that look a lot like the AC ones with electronic control instead of the earlier mechanical/ magnetically systems these later Pabst motors have more wires going into them.

Yes, sometimes the same motor can be operated synchronously or asynchronously depending on the controller. Systems that rely on drag to control the speed must be asynchronous.

Unless we have the full details of the implementation it is hard to consider if it is voltage or frequency feedback - some motor controllers have two loops of feedback - one for optimum drive, the other for speed accuracy.

Three phase drive of three phase synchronous motors is trivial - we can fine tune phase and amplitude of each drive for maximum smooth. There are several suppliers of such units - I remember for example, Jaap Pees of Hanze HiFi that developed an unit for the EMT 927 that is used by several owners.

 

[ddk]

Are you saying feedback drives voltage? If speed is correct does that count as correction?

Speed is held with constant monitoring and continuous adjustment by the management software and a microprocessor not free spinning like an ac synchronous motor.which requires none of that.

david