TT motor voltage.

Paul Dimaline · 3rd March 2006, 08:16 PM

OK, I am going with a Premotec synchronous motor for my DIY Idler drive project. With my chosen motor, here (35104 or 35504) I have a choice between 24 or 220 volt operation, (these are the only ones stocked by the UK distributor, all others are dependant upon a minimum order number)

Specifications seem to be the same for both voltages so which one do you think I should go for? I,m thinking perhaps the 24 volt would be less likely to upset the cartridge, or wont it matter?

Paul.

Mark Kelly · 3rd March 2006, 10:00 PM

Don't use either.

Synchronous motors are very difficult to handle in idler drive applications because a synchronous motor has no torque reserve the way a DC or induction motor does. To see what I mean by this look at the torque curves on the attached web page - you will see that both the induction motor and the DC motor will provide significantly higher than their rated torque during the run - up.

A synch motor does not do this, it starts at full speed and if that requires more than its rated torque then it doesn't start at all. If you use a motor with enough torque to start it will cause a lot of stress on the idler mechanism as it jumps to speed in a matter of milliseconds. I use a three phase EC motor (basically an advanced version of a synch motor) in my 301 and I had to change the drive electronics so it started at half speed then went to full speed to reduce this problem.

Turntable Motors

Paul Dimaline · 4th March 2006, 05:24 PM

Mark, thanks for the info and I found your site very interesting.

I see what you mean, I think! My biggest problem is that I have no knowledge or expertise in designing or building electronic circuits, that is the reason that I wanted to go the synchronous motor route.

Also the design I have in mind probably goes against the popular norm for TT design. I am going to build an Idler drive, but without the idler wheel. The motor will be pivoted and drive a sub platter directly. If the idea looks like working I will take the design further and decouple the main platter from the sub platter. I anticipate much tinkering and tweeking so i cant afford to spend large amounts of money on it at this momment.

Is the main problem going to be one of sudden take up of the drive train? If so I have an idea how to get round that. As I am not going for a high mass platter I doubt the motor will stall....

3rd March 2006, 08:16 PM	#1
Paul Dimaline diyAudio Member Join Date: Feb 2004 Location: Lincolnshire, UK	TT motor voltage. OK, I am going with a Premotec synchronous motor for my DIY Idler drive project. With my chosen motor, here (35104 or 35504) I have a choice between 24 or 220 volt operation, (these are the only ones stocked by the UK distributor, all others are dependant upon a minimum order number) Specifications seem to be the same for both voltages so which one do you think I should go for? I,m thinking perhaps the 24 volt would be less likely to upset the cartridge, or wont it matter? Paul.

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3rd March 2006, 10:00 PM	#2
Mark Kelly diyAudio Member Join Date: Feb 2006 Location: Geelong	Don't use either. Synchronous motors are very difficult to handle in idler drive applications because a synchronous motor has no torque reserve the way a DC or induction motor does. To see what I mean by this look at the torque curves on the attached web page - you will see that both the induction motor and the DC motor will provide significantly higher than their rated torque during the run - up. A synch motor does not do this, it starts at full speed and if that requires more than its rated torque then it doesn't start at all. If you use a motor with enough torque to start it will cause a lot of stress on the idler mechanism as it jumps to speed in a matter of milliseconds. I use a three phase EC motor (basically an advanced version of a synch motor) in my 301 and I had to change the drive electronics so it started at half speed then went to full speed to reduce this problem. Turntable Motors

4th March 2006, 05:24 PM	#3
Paul Dimaline diyAudio Member Join Date: Feb 2004 Location: Lincolnshire, UK	Mark, thanks for the info and I found your site very interesting. I see what you mean, I think! My biggest problem is that I have no knowledge or expertise in designing or building electronic circuits, that is the reason that I wanted to go the synchronous motor route. Also the design I have in mind probably goes against the popular norm for TT design. I am going to build an Idler drive, but without the idler wheel. The motor will be pivoted and drive a sub platter directly. If the idea looks like working I will take the design further and decouple the main platter from the sub platter. I anticipate much tinkering and tweeking so i cant afford to spend large amounts of money on it at this momment. Is the main problem going to be one of sudden take up of the drive train? If so I have an idea how to get round that. As I am not going for a high mass platter I doubt the motor will stall....