Direct Drive - any advantage to coreless motors?

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Max N
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Direct Drive - any advantage to coreless motors?

Post by Max N » Tue Aug 06, 2019 1:07 am

Do coreless motors offer any advantages over cored motors when it comes to direct drive turntables?
I know they offer less cogging, but is the cogging already negligible in the best cored motors?

The motion platforms we use in the simulators at work use coreless motors, but we were able to get the force we wanted at an acceptable weight so it was an easy choice. We had to pay quite a lot of money to get acceptable feel for the steering, early attempts with cored motors gave a lot of cogging feel. In the end we used an outside an company who had a lot of experience with control loading for simulators. The trick parts there are the control system and a very good torque sensor to close the loop.

Neal
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Re: Direct Drive - any advantage to coreless motors?

Post by Neal » Tue Aug 06, 2019 9:03 am

I think the answer is yes to your question Max. Well, Technics seem to think so... https://www.technics.com/uk/products/gr ... 210gr.html
Only the Sith deal in absolutes.

Max N
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Re: Direct Drive - any advantage to coreless motors?

Post by Max N » Tue Aug 06, 2019 3:23 pm

That’s interesting information, thanks Neal.
Were any of the vintage JVCs or Kenwoods cordless I wonder....

Ant
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Re: Direct Drive - any advantage to coreless motors?

Post by Ant » Tue Aug 06, 2019 4:06 pm

I think my QL-Y5F has a coreless motor iirc

Max N
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Re: Direct Drive - any advantage to coreless motors?

Post by Max N » Tue Aug 06, 2019 8:41 pm

Ant wrote:
Tue Aug 06, 2019 4:06 pm
I think my QL-Y5F has a coreless motor iirc
Hmmmm
I've been thinking of getting one of the JVCs for a while, largely based on your recommendation!
Maybe I'll do a bit more research while I'm saving up.....

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Re: Direct Drive - any advantage to coreless motors?

Post by Neal » Tue Aug 06, 2019 9:25 pm

Max N wrote:
Tue Aug 06, 2019 3:23 pm
That’s interesting information, thanks Neal.
Were any of the vintage JVCs or Kenwoods cordless I wonder....
Yes, I have a KD990 that has a coreless motor, there are probably others...
Only the Sith deal in absolutes.

Ant
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Re: Direct Drive - any advantage to coreless motors?

Post by Ant » Tue Aug 06, 2019 10:05 pm

I think the jvc tt71 motor unit is coreless aswell, those are in the ql70 and ql7. Loads of these types of motor units in Germany at fairly reasonable money
Also the denon range may be coreless but I'm not sure.
I know Greg is really happy with his dp80, and the dp2000 I used to have was a lovely unit but wasn't quartz lock or pll.
That one had something like a tape head that read the ferrite strip on the inside of the platter edge.
Out of all the dd units I've had the only ones I didn't really get on with were the technics ones, not the sp10 15 20, never had one of those, the ones with the sl1200 style motor where the platter is the rotor. Their earlier self contained motors like the matsushita mkl 15b and its variants in the sl2000 and my jbe and various kenwoods are in my experience better motors.
Had a couple of sonys, but nothing that was particularly nice so I couldn't say what their better motor units are like
Goldmund used a jvc motor in their studio turntable in the early 80s too, and lad used jvc motors for their dj decks too.

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IslandPink
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Re: Direct Drive - any advantage to coreless motors?

Post by IslandPink » Tue Aug 06, 2019 10:26 pm

Yer in danger of becoming an expert on these things, Ant.
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

Ant
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Re: Direct Drive - any advantage to coreless motors?

Post by Ant » Tue Aug 06, 2019 10:54 pm

Nope just a boring git :D
This is a nice one, arm is a ua5045 which is no slouch either. Looks higher mass than it actually is and is abit longer than a rega, about 230 s/p distance
Bit dear though
https://rover.ebay.com/rover/0/0/0?mpre ... 3843546852

Edit: tt71 isn't coreless, it's the later ones that are

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rowuk
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Re: Direct Drive - any advantage to coreless motors?

Post by rowuk » Wed Aug 07, 2019 5:35 pm

I think that most people that really listen would be at odds to say what the sonic contribution of a specific technology is. The problem is figuring out how much is the plinth, mechanical grounding, weight and damping of the platter and then maybe finally the motor. My experience is that the motor has the smallest effect on the sonics as any well maintained motor technology is at or below the threshold of audibility. The most vulnerable part is the platter bearing (which could also be the motor bearing). Generally vintage turntables do not get the tender loving care that they should have and the bearings develop flat spots.

I am using a Kenwood KD600 motor in my record deck. 20-pole 30 slot brushless DC servo motor
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IslandPink
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Re: Direct Drive - any advantage to coreless motors?

Post by IslandPink » Wed Aug 07, 2019 6:05 pm

Nice unit !
rowuk wrote:
Wed Aug 07, 2019 5:35 pm
I think that most people that really listen would be at odds to say what the sonic contribution of a specific technology is.
I would disagree. Having had a few decks of different types over the years, I would say that it becomes fairly obvious that the low bass and timing are mainly affected by the torque of the motor and the method of drive ( belt/idler/direct ). In the midrange there's a lot of overlap, and all parts of the system can contribute - there may be some swapping or blending that can be taken advantage of. In the HF there's still plenty of overlap, but the headshell and arm play proportionally a bigger part.
One thing that came as a surprise is that platter mass will only take you so far in getting low bass and timing. Having had an LP12, then a Garrard 401, then bought a new Nottingham Hyperspace, I was quite amazed at the further improvement in going from the weak belt-drive motor Nottingham supply to a rim-drive pod with a more powerful motor ( Verus ).
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

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rowuk
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Re: Direct Drive - any advantage to coreless motors?

Post by rowuk » Wed Aug 07, 2019 6:44 pm

IP,
yes, but with each of those changes in technology EVERYTHING else changed at the same time. Could it just be that those with "weak" belt drives have plinth or mechanical grounding issues? Could it be that there is a critical platter mass for a given motor/drive system and that the manufacturers did not hit the sweet spot? If torque is a blessing for the low end, respectable direct drive decks should own low bass. I learned a lot with a Thorens TD-160, a Dual 700 series and the Kenwood. I played with the suspension, plinth mass, platter mass and damping, coupling to shelves, arm mounts on each of those and was surprised at the huge differences - even with the same motor and arm.

I am not arguing tendencies, I just have trouble pointing at the motor technology as there are so many other mechanical factors with a far bigger "voice". I have yet to hear an idler drive with an absolute black background although it certainly must be possible.
Whenever I feel blue, I start breathing again.

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