Primary Control Kinea turntable

morricab

Well-Known Member
Apr 25, 2014
3,417
488
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Switzerland
#21
We can use most DC motors without feedback or servo - just supplying them with three sinusoidal phases as people do with synchronous drives. I did it long ago with good results in an Oracle III, that used a brushless DC motor. The amplitude of the waveform should be adjusted for optimal drive and minimum noise.
A brushless sinusoidal EC motor is NOT a DC motor. It is a misnomer that stuck.
 
May 30, 2010
15,504
713
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Portugal
#22
A brushless sinusoidal EC motor is NOT a DC motor. It is a misnomer that stuck.
Sorry, It is accepted practice in engineering, although probably purist audiophiles do not like it. Even wikipedia says :

"A DC motor is any of a class of rotary electrical machines that converts direct current electrical energy into mechanical energy. "

Brushless motors are considered a subclass of DC motors.
 

morricab

Well-Known Member
Apr 25, 2014
3,417
488
83
Switzerland
#23
Sorry, It is accepted practice in engineering, although probably purist audiophiles do not like it. Even wikipedia says :

"A DC motor is any of a class of rotary electrical machines that converts direct current electrical energy into mechanical energy. "

Brushless motors are considered a subclass of DC motors.
Yet they don’t run on direct current. Think about it ... they run on a sinusoidal waveform or another kind of waveform but not DC.
 
May 30, 2010
15,504
713
113
Portugal
#24
Yet they don’t run on direct current. Think about it ... they run on a sinusoidal waveform or another kind of waveform but not DC.
Then you would also conclude that brushed DC motors do not run on DC but on square waves, the current is reversed every half turn by the commutator. Semantics are nice for poetry and audiophilia, not for these technical matters.
 

Folsom

VIP/Donor
Oct 26, 2015
3,798
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Eastern WA
#25
Using a capacitor for the second phasing on an AC motor is the old lame way. Now you use a two channel amp putting out one frequency 90* off, with adjustable frequency for both amp channels to tune speed of the TT.
 
May 30, 2010
15,504
713
113
Portugal
#26
Using a capacitor for the second phasing on an AC motor is the old lame way. Now you use a two channel amp putting out one frequency 90* off, with adjustable frequency for both amp channels to tune speed of the TT.
Yes, perfectionists can even adjust the last fraction of degree of the phase angle and the individual amplitudes of each phase for minimum measured noise or imaginary best sound quality ...;)

Some turntables - the TechDas Air Force one for example - use the nominal voltage during start-up and reduce voltage to the optimum voltage during playback.
 

morricab

Well-Known Member
Apr 25, 2014
3,417
488
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Switzerland
#28
Then you would also conclude that brushed DC motors do not run on DC but on square waves, the current is reversed every half turn by the commutator. Semantics are nice for poetry and audiophilia, not for these technical matters.
No, because what you feed the motor is DC...at least that is what I feed my brushed DC pancake motor ;). A brushless DC motor gets fed an AC waveform (EC)....typically a sinusoidal waveform for a TT motor. The two motors, despite having DC in the name, are driven very differently...it is you getting hing up on semantics not I.
 
#29
Hi!

I've tried to make this questions in another thread, but since there was no answer, I decided to open a thread about this gorgeus turntable.
Copy/paste:
https://www.whatsbestforum.com/thre...log-lines-to-the-usa.22825/page-3#post-583229

"The Kinea turntable looks lovely, I'm unable to afford to buy one at the moment, but I would like to make a couple of questions, just out of curiosity:

- Does it feature a servo for speed regulation? The Brinkmann direct drive turntables, while being low torque, use (a very small amount) of speed regulation, the only turntables I know of that are direct drive but do not use servos or speed regulation of any kind are the Kodo the Beat (40k with tonearm, ouch!) and the Teres Certus (discontinued).

- Is the record mat an integral part that plays "with a special synergy" on the turntable, or can it be changed for another one? To be honest, at least in pictures, looks a bit ugly, not in line with the sophisticated, really well thought out turntable IMHO.

The last one is just a suggestion, but they should put the PSU/speed controller in a nicer, CNC milled box, even if it raises the price 500-1000$, the box looks like something anyone could buy at Modushop or Audiophonics, it doesn't do justice to the beauty of the turntable, again IMHO. "

Just to add something, I've tried to google-fu about this gem but there's very, very little info about it on the web, just a couple of threads here, some show reports and some words on Vinyl Savor, but nothing in depth about the design.
Again, sorry if I come across as somewhat impatient/too curious, hope y'all have a nice week! :)


Dear All,

Joshua from Believe High Fidelity has informed me that WBA has a thread about our Kinea Turntable.

@marmota
Thank you for your feedback on our Kinea Direct Drive Turntable.
With some delay, I would like to give an answer to your questions.
Please also allow me to describe a feature of our turntable that is often overlooked or misunderstood.

The turntable mat is interchangeable with other designs as long as they have a dampening effect on the aluminum platter. We have tried many different mats and have always come back to this rather ordinary rubber mat, as the reproduction is very neutral. Many other mats we’ve tried have an emphasis effect to some frequency range that does not fit our design goals.
In reality, it may not look as spectacular as a brass platter mat, but in our opinion, it fits in with the noble appearance of the turntable.

The Kinea TT uses a brushless motor with a device that generates a voltage proportional to the speed. A voltage comparator supplies the control signal for the feedback.

In our opinion, a very important feature of the motor controller is the ability to change the motor control (maximum) current, allowing the user to change the motor torque in three settings.
The motor itself with air coils is a low torque motor design.
We have a low, medium and high torque motor setting. To start up and change the speed, the controller uses high torque for about 5 seconds and then returns to the user setting.
To keep the torque as low as in our low torque setting, we use a 350mm diameter platter to increase the dynamic platter mass without making the platter too heavy.

What is the benefit of changing the torque of a motor?
In the development of the direct drive Kinea Turntable, we have tried different motors and found that the regulator (maximum) current has a significant impact on the sound quality of the table.
In listening tests, we also find that there was no particular setting that all listeners preferred at the same time.
For this reason, we decided to build a motor controller with variable torque settings.

Bernd
PrimaryControl
 

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