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Spider27

Most Ideal type of motor for turntable

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It got me curious types of motors are used in turntables and I spent some time last  few days browsing internet and found that there are two main types of motors are used for turntable as far as I understand.

 

Belt Driven Turntable: AC motors

Direct Drive Turntable: Brushless DC motor

Vintage Idler Turntable: AC motors

 

I am sure there are a few exceptions that Belt Driven uses Brushless DC motors but none of direct drive TT uses AC motors if I understood correctly.

 

Why Brushless DC motors which has more torque with precious speed control are not used in belt driven turntable? If is because of cost? Or Belt Driven turntable does not require high torque so use  cheaper AC motor? If it is cost issue, it does not make sense since very high end belt driven turntable manufacturers (Linn, Kuzuma, Mitchell, Rega, ClearAudio) still use AC motors. Or, is there a benefit of using AC motors against Brushless DC?

 

And, how about hybrid stepper motors which some people claim that is the best of both servos and DC motor? If I understand, none of turntable utilise this type of motors. 

 

Could you please enlighten me on this? 

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2 hours ago, Ian McP said:

 

Couldnt hear much of what he was saying because of that crap music in the background.

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26 minutes ago, Wimbo said:

Couldnt hear much of what he was saying because of that crap music in the background.

It’s a brushless 3 coil DC brushless programmable motor,  in other words a DC brushless stepper motor.

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Posted (edited)

@andyr should chime in.

 

the motor is one part of the equation, the other factor that completes the equation is the circuit that drives it.

 

If I were to get back into TT I’d be looking at what @andyr uses,  he has access to a prohibited member here who knew exactly how to control that motor.....  Better than any other high profile company.  There was a thread here that shows what LInn uses and what he had achieve on a scope.

Edited by Addicted to music

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1 minute ago, Addicted to music said:

@andyr should chime in.

 

the motor is one part of the equation, the other factor that completes the equation is the circuit that drives it.

 

If I were to get back into TT I’d be looking at what @andyr uses,  he has access to a prohibited member here who was but he knew exactly how to control that motor.....  Better than any other high profile company.  There was a thread here that shows what LInn uses and what he had achieve on a scope.

Check out the new Sota motor and power supply I posted as well.

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1 minute ago, Wimbo said:

https://sotaturntables.com/products/eclipse-package/

New power supply and motor. Belt drive.

They have the best suspension for the money,  I’ve actually seen this done with my own eyes at Tivoli HiFi in Camberwell when they were the appointed sales agent......    

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5 hours ago, Spider27 said:

I very high end belt driven turntable manufacturers (Linn, Kuzuma, Mitchell, Rega, ClearAudio) still use AC motors. Or, is there a benefit of using AC motors against Brushless DC?

 

 

Linn use a Brushed DC motor in their Radikal along with propitiatory electronics....

 

quite as anything I've heard...no pun intended... 

 

Tase.

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5 hours ago, Spider27 said:

 

And, how about hybrid stepper motors which some people claim that is the best of both servos and DC motor? If I understand, none of turntable utilise this type of motors. 

 

Could you please enlighten me on this? 

Motor technology have come along way since the 80s when I was getting involve with TT.    

Im actually surprised that companies like Rega still use simple AC motors that actually sync with the mains...    most TT manufacturers haven’t looked at or haven’t seen the tech that’s available,  why change something that’s going to cost in R&D when your current product works well!    if you want the latest and greatest then go for DC brushless synchronise stepper motor..   Brushless for reliability and efficiency, synchronised stepper so they know exactly where that position is with X amount of drive pulse,   to reduced torque pulses some have gone to the extent that the  magnet is housed on the outside and it is used to spin!  They also have Hall effect sensors so there speed can be monitored .   But I’d bet that even the motor shown in the above clip will have a coil on a shaft to spin, nothing wrong with that.   It all depends on the technology you wanna engage in.  Like I said before you also need a dedicated circuit to drive it for the application.  Just chose your poison.

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Posted (edited)
8 minutes ago, Tasebass said:

....like to see this repeated using a Unipivot...

 

Tase

Mmmm,  bet ya it’ll be a different result with a LInn....and I would not  try it on a ......LInn. 😜

Edited by Addicted to music

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3 minutes ago, Addicted to music said:

Mmmm,  bet ya it’ll be a different result with a LInn....and I would not  try it on a ......LInn. 😜

Not with an DV XV1s on the end of it....:tongue:

 

 

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42 minutes ago, Addicted to music said:

Motor technology have come along way since the 80s when I was getting involve with TT.    

Im actually surprised that companies like Rega still use simple AC motors that actually sync with the mains...    most TT manufacturers haven’t looked at or haven’t seen the tech that’s available,  why change something that’s going to cost in R&D when your current product works well!    if you want the latest and greatest then go for DC brushless synchronise stepper motor..   Brushless for reliability and efficiency, synchronised stepper so they know exactly where that position is with X amount of drive pulse,   to reduced torque pulses some have gone to the extent that the  magnet is housed on the outside and it is used to spin!  They also have Hall effect sensors so there speed can be monitored .   But I’d bet that even the motor shown in the above clip will have a coil on a shaft to spin, nothing wrong with that.   It all depends on the technology you wanna engage in.  Like I said before you also need a dedicated circuit to drive it for the application.  Just chose your poison.

Thank you and great to know that DC brushless synchronise stepper motor are now getting used such as Thomas Schick. 

 

May I ask what synchronise means in this case? Does it mean that stepper motor gets micro stepping so increase number of steps in a round for accurate positioning and less vibration? 

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Posted (edited)
1 hour ago, Spider27 said:

Thank you and great to know that DC brushless synchronise stepper motor are now getting used such as Thomas Schick. 

 

May I ask what synchronise means in this case? Does it mean that stepper motor gets micro stepping so increase number of steps in a round for accurate positioning and less vibration? 

synchronise motors are motors where the rotor speed and the speed of the magnetic field is equal.

asynchronous motors is a motor who’s rotor rotates at less than the synchronous speed.

You can microstep a stepper motor,  this explains it a lot better how you can do it and you can see how they control the position in steps...   Notice he got this stepper motor out of an old printer.....  notice the magnet is on the rotor and the coil stationary.   

 

Edited by Addicted to music

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Hello,

For me the most ideal type of motor for turntable is the direct drive motor.

It is neat, elegant and can be made as precise as one will. It can be very powerful (studio decks) or not.

It has no expendable  parts (belts, idlers... ) so it is also very long lived.

And cherry on the cake, it is independent of mains voltage and frequency.

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2 hours ago, georgesgiralt said:

 

Hello,

For me the most ideal type of motor for turntable is the direct drive motor.

 

 

So there are no downsides to a direct-drive motor, George?  :lol:

 

2 hours ago, georgesgiralt said:

And cherry on the cake, it is independent of mains voltage and frequency.

 

 

So is an AC motor driven by a frequency circuit - such as the 'Number9', which I  use.  The frequency fed to the AC motor by the motor controller determines the speed of the motor - and, hence, the platter.  The voltage fed to the motor - again, controlled by the motor controller - affects the sound you hear.  (Hint - higher sounds better than lower; but you need a way of 'tuning' the capacitance between the two motor windings, to minimise motor vibration.

 

Andy

 

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Any one care to comment on my basic understanding that the main issues with the different motors are that;

 

DC motors are always hunting for the correct speed and that the control electronics manage how "wrong" it is?  But, the motor has less vibration than an AC motor.

 

And AC synchronous motors have the same speed relative to the number of poles and the waveform frequency but vibration is greater due to cogging where the motor "lurches" toward and past with the changing rotational forces as the poles rotate, the effect of cogging being related to motor voltage i.e. lower voltage less cogging effect and from what Andyr has said "tuning the capacitance".

 

@andyr are you "tuning" the capacitance or changing the phase angle between the sine waves being fed to each motor winding?  I understand the Valhalla uses capacitance to change the phase angle but would have thought the number9 would have been generating two independent sine waves.

 

 

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Theory aside, nothing beats a big idler drive with a big-arse "washing machine" motor hanging off it.  Seriously IMHO :) 

 

If you want to build a big sinewave power source to feed it - and hence control the frequency of the power, and so the speed, that too is good, but make it a good one with plenty of drive.

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Posted (edited)
3 hours ago, tesla13BMW said:

 

Any one care to comment on my basic understanding that the main issues with the different motors are that:

 

DC motors are always hunting for the correct speed and that the control electronics manage how "wrong" it is?  But, the motor has less vibration than an AC motor.

 

 

That's my understanding, too.  :)  The speed of a DC motor is controlled solely by the voltage fed to it - hence how the motor controller controls this voltage is key to how well the motor delivers a constant 33 1/3rd or 45rpm.

 

Quote

 

And AC synchronous motors have the same speed relative to the number of poles and the waveform frequency but vibration is greater due to cogging where the motor "lurches" toward and past with the changing rotational forces as the poles rotate, the effect of cogging being related to motor voltage i.e. lower voltage less cogging effect and from what Andyr has said "tuning the capacitance".

 

@andyr are you "tuning" the capacitance or changing the phase angle between the sine waves being fed to each motor winding?  I understand the Valhalla uses capacitance to change the phase angle but would have thought the number9 would have been generating two independent sine waves.

 

 

Yes, bad phrasing on my part, Chris.  :(

 

One of the key 'Number9' features IMO is the ability to vary the phase angle between the 2 sine waves fed to the AC motor.  This enables you feel  the optimum phase angle - by holding the motor in your hand, whilst you change the phase angle.  NB: the optimum phase angle certainly isn't 90 deg - which is what a cap gives you!  :lol:

 

I suspect that this minimum level of vibration could be down at the level of a DC motor - negating the key advantage of a DC motor!  :)  Why I say this is that minimising motor vibration enables you to increase the voltage fed to the motor; this has a positive effect on SQ but, as you said, increases the level of motor vibration.  Having minimised motor vibration by selecting the right phase angle, I am able to run my 24v Premotecs at 28v!  (In fact, 30v sounds better - and 32v sounds even better - but higher voltages reduce the life of the motor; I found 28v does not shorten the life of the motor - so that's the 'sweet spot' in terms of SQ vs. motor life.)

 

Andy

 

Edited by andyr

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54 minutes ago, andyr said:

my 24v Premotecs

Hi Andy

I see Rega and Linn, with the Lingo 4, are now also running 24v motors. Do you know if these are Premotecs, the same, or similar to yours?

 

Cheers

 

Grant 

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@gnnett the Lingo 4 has gone lower again using a 12VAC motor.

 

As I understand it the Number9 24VAC motor that Stephen Tuckett uses is identical to the Rega motor other than it is a flange mount.

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Hello Spyder,

 

I suspect that the "most ideal type of motor" will depend on the operating principles that the TT designer chooses for a particular design:-

  • heavy vs light platter
  • sprung vs unsprung system
  • resistance-type vs free-spinning bearing

No one motor type is ideal for all these design decisions.

 

Regards

Grant Slack

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37 minutes ago, gnnett said:

Hi Andy

I see Rega and Linn, with the Lingo 4, are now also running 24v motors. Do you know if these are Premotecs, the same, or similar to yours?

 

18 minutes ago, tesla13BMW said:

@gnnett the Lingo 4 has gone lower again using a 12VAC motor.

 

As I understand it the Number9 24VAC motor that Stephen Tuckett uses is identical to the Rega motor other than it is a flange mount.

 

Grant, I can confirm that the 2x 24v AC motors I'm using on my 'SkeletaLinn' are standard Premotecs.  I've only ever seen Premotecs with a flange mount - so can't comment on what Rega motors actually look like.  :(

 

However, this 24v Premotec was the first motor that Steve chose to use with his 'Number9' (because he was going after the Rega customer base); he now offers output modules for a number of other motors - including VPI and Linn (110v).

 

Andy

 

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