Saskia model two

spiritofmusic

Well-Known Member
Jun 13, 2013
9,059
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E. England
#81
As you know Bill, Vic the designer of my rim/idler Salvation could not get an optical feedback system to work re moment to moment micro correction of speed. Whatever he tried led to a coldness or greyness in sound. Even the neat trick of measuring and correcting microvariations in voltage swings as speed changes led to changes in motor voltage output (or something like that), led to negatives in SQ.

Vic settled on simple analog "set (via strobe disc) and forget (for a few days at a time)".

Maybe Saskia also dispenses w speed measure/adjust loop?
 

bonzo75

Member Sponsor
Feb 26, 2014
11,880
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#82
Hi Mike,

Is the Saskia AC or DC motor? How is speed controlled accurately in this implementation? I know the Blackstone uses an optical encoder type approach. Wondered whether Saskia did similar.

Cheers
It's a 3 phase pabst. That gives the hustle and flow
 

spiritofmusic

Well-Known Member
Jun 13, 2013
9,059
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#83
Yes, but how does it keep correct speed?
 

Mike Lavigne

Member Sponsor & WBF Founding Member
Apr 25, 2010
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#86
Hi Mike,

Is the Saskia AC or DC motor? How is speed controlled accurately in this implementation? I know the Blackstone uses an optical encoder type approach. Wondered whether Saskia did similar.

Cheers
hi Bill,

don't know about AC or DC motor.

Win did describe how the Saskia motor controller regulates speed. but it was in the mix of other info and was pretty deep. i know that (1) it's an analog controller, (2) it does not have a feedback loop so the speed does not 'hunt', and (3) it is software up-gradable.....there is a connection on the back side for that purpose. an optical reader is installed under the platter which is currently not functional. you can see it in the 3rd picture down in this post (that black post sticking up next to the bearing tower);

https://www.whatsbestforum.com/threads/saskia-model-two.28727/#post-591275

at some point that may be part of an upgrade.

one big difference between the original Saskia and the model two is the controller/power supply which Win had help designing. next time i speak to Win i will revisit this topic and take some good notes. sorry i can't be more detailed at this time. btw; that power supply/speed controller weighs 40 pounds and 70 watts to run....not trivial.

the moral of the story is 'first do no harm'. i think when you have awesome speed performance that there is a point at which making things more complicated moves you in the wrong direction for the music. i love that Win is not looking for adding complexity for it's own sake. but he provided for a step forward when/if that can happen.
 
Last edited:

Audiophile Bill

Well-Known Member
Mar 23, 2015
2,474
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113
UK
#87
hi Bill,

don't know about AC or DC motor.

Win did describe how the Saskia motor controller regulates speed. but it was in the mix of other info and was pretty deep. i know that (1) it's an analog controller, (2) it does not have a feedback loop so the speed does not 'hunt', and (3) it is software up-gradable.....there is a connection on the back side for that purpose. an optical reader is installed under the platter which is currently not functional. you can see it in the 3rd picture down in this post (that black post sticking up next to the bearing tower);

https://www.whatsbestforum.com/threads/saskia-model-two.28727/#post-591275

at some point that may be part of an upgrade.

one big difference between the original Saskia and the model two is the controller/power supply which Win had help designing. next time i speak to Win i will revisit this topic and take some good notes. sorry i can't be more detailed at this time. btw; that power supply/speed controller weighs 40 pounds and 70 watts to run....not trivial.

the moral of the story is 'first do no harm'. i think when you have awesome speed performance that there is a point at which making things more complicated moves you in the wrong direction for the music. i love that Win is not looking for adding complexity for it's own sake. but he provided for a step forward when/if that can happen.
If there is an encoder, surely there has to be some form of feedback circuit to then adjust the speed if it is detected as straying?
 

Mike Lavigne

Member Sponsor & WBF Founding Member
Apr 25, 2010
7,769
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#88
If there is an encoder, surely there has to be some form of feedback circuit to then adjust the speed if it is detected as straying?
sorry if i was not sufficiently clear.

there is an optical reader but it is NOT functional. it's there in case they can advance the performance by adding a feedback circuit. so far they have not done that.....i don't know how far along they are to adding that, if at all. what i recall is that doing that is a possibility.....but ONLY if it improves the performance.
 

Audiophile Bill

Well-Known Member
Mar 23, 2015
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#89
sorry if i was not sufficiently clear.

there is an optical reader but it is NOT functional. it's there in case they can advance the performance by adding a feedback circuit. so far they have not done that.....i don't know how far along they are to adding that, if at all. what i recall is that doing that is a possibility.....but ONLY if it improves the performance.
Oh I see. Got it.

I wonder how it maintains its speed stability in the current model then?
 

spiritofmusic

Well-Known Member
Jun 13, 2013
9,059
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E. England
#90
Bill, does Vyger run an optical encoder/feedback loop to aid micro speed adjustment? Or do you just get it to the right speed via help w strobe disc/Timeline etc? And maybe readjust manually every few days/wks/months?
 

Mike Lavigne

Member Sponsor & WBF Founding Member
Apr 25, 2010
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#91

Audiophile Bill

Well-Known Member
Mar 23, 2015
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#92
Bill, does Vyger run an optical encoder/feedback loop to aid micro speed adjustment? Or do you just get it to the right speed via help w strobe disc/Timeline etc? And maybe readjust manually every few days/wks/months?
I actually don’t know in honesty. It doesn’t change speed from month to month. I went around 7 months between checking and it was still exactly what it was. Definitely no readjust required at all in my experience.
 

tima

Industry Expert
Mar 4, 2014
915
449
63
#93
I actually don’t know in honesty. It doesn’t change speed from month to month. I went around 7 months between checking and it was still exactly what it was. Definitely no readjust required at all in my experience.
What do you use to check yr Vyger's speed?
 

spiritofmusic

Well-Known Member
Jun 13, 2013
9,059
1,063
113
E. England
#94
Bill, that is scary good. I wonder how much harder it is to get a high torque idler like Saskia to the same level of accuracy.

I'm about to buy the current iteration of Roadrunner speed measuring device. My idler/rim Salvation needs a nudge to correct every other day.
 
Likes: Lagonda

ddk

Industry Expert
May 19, 2013
3,963
498
83
Utah
#96
If there is an encoder, surely there has to be some form of feedback circuit to then adjust the speed if it is detected as straying?
Not necessarily, you control ac frequency, ramp up and ramp down speeds of the motor nothing to do with feedback loops. Software upgrades if any usually have to do with ramping times, this way you have programing flexibility incase further fine-tuning is needed

david
 

tima

Industry Expert
Mar 4, 2014
915
449
63
#97
I have a Clearaudio strobe disc and I use 2 platter apps on iPhone - one called RPM and the other called Turntabulator.
Do the phone apps give the same reading?

Not a comment on what you're doing: I'm curious if there is variability across the use of phone apps for measuring speed, not because of the apps but because of the phones. I'd like to see an experiment with say ten instances of the same phone and app simultaneously, to assess variability and consistency
 
May 30, 2010
15,501
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Portugal
#98
If there is an encoder, surely there has to be some form of feedback circuit to then adjust the speed if it is detected as straying?
The AirForce one makes an intelligent use of the encoder - it uses feedback during startup to reach the exact speed and afterwards forgets about it, driving the phases of synchronous motor with the optimized constant amplitude and frequency .
 

Audiophile Bill

Well-Known Member
Mar 23, 2015
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#99
Not necessarily, you control ac frequency, ramp up and ramp down speeds of the motor nothing to do with feedback loops. Software upgrades if any usually have to do with ramping times, this way you have programing flexibility incase further fine-tuning is needed

david
Thanks David. What is the optimal way for controlling frequency in TT external power supplies?
 

Audiophile Bill

Well-Known Member
Mar 23, 2015
2,474
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The AirForce one makes an intelligent use of the encoder - it uses feedback during startup to reach the exact speed and afterwards forgets about it, driving the phases of synchronous motor with the optimized constant amplitude and frequency .
Okay makes sense. Thanks Micro.
 

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