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The Technics SL-1200 GAE/G/GR general questions thread

Discussion in 'Audio Hardware' started by Halloween_Jack, Aug 1, 2018.

  1. Ingenieur

    Ingenieur I love to travel, but I hate to arrive.

    Location:
    PA
    Very clever motor design
    8 pole armature/stator
    Basically infinite pole field/rotor
    Smooth
    AC motor approaching DC
    FREQ = 33.333 / 120 x 8 = 2.222 Hz
     
  2. Davey

    Davey Heavy Rotation: Chihei Hatakeyama - Late Spring

    Location:
    SF Bay Area, USA
    Yea, basic design goes back to the original Dual CS 701 with the EDS-1000 coreless 8-pole motor in 1973, many of the subsequent coreless direct drive motors were derived from that one, some a bit too closely and they ran into patent problems. The new Technics motors are actually 9-pole designs, as shown in the illustrations in post above.


    [​IMG]
     
    Last edited: May 16, 2021
    JohnO, Oelewapper, Hardcore and 2 others like this.
  3. Ingenieur

    Ingenieur I love to travel, but I hate to arrive.

    Location:
    PA
    Thanks
    Never said I could count :D
    The bad part? I counted 1/2 dozen times, kept losing the starting point :biglaugh:

    Makes f = 2.50000 Hz
     
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  4. JP

    JP Forum Resident

    Location:
    Brookfield, CT
    I see 9 slots, but how do you know how many poles?
     
  5. Ingenieur

    Ingenieur I love to travel, but I hate to arrive.

    Location:
    PA
    It's kind of blurred, lol
    You have 9 armature/stator coils
    But the field/rotor magnet is continuous
    But for it to rotate the AC must rotate around the coils.

    most motors are concentric, this is planar

    Not sure what to call them other than poles.
    I'd like to see how the coils are wired.
     
  6. JP

    JP Forum Resident

    Location:
    Brookfield, CT
    Doesn't change how a motor works. Between each coil is a slot. Poles are magnetic - we can count those via attraction, or if we knew the drive frequency and phases we can calculate them.
     
  7. Davey

    Davey Heavy Rotation: Chihei Hatakeyama - Late Spring

    Location:
    SF Bay Area, USA
    These are coreless, slotless motors we are talking about here. The poles are magnetic domains formed within the magnet structure, kind of like shown in illustration below, which would be like the SL-1200G motor with the twin rotors sandwiching the windings ... Technics says it is a 9-pole motor, and Dual said the EDS-1000 was a 8-pole motor, that's how you know, but you can also guess by the number of stator windings. The Dual EDS-1000 motor has two offset layers of 8 bifilar windings, as shown in picture below ...

    [​IMG]


    [​IMG]
     
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  8. Hardcore

    Hardcore Quartz Controlled

    Location:
    UK
    Here’s the G with dual rotors.

    [​IMG]

    [​IMG]

    [​IMG]
     
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  9. Ingenieur

    Ingenieur I love to travel, but I hate to arrive.

    Location:
    PA
    Last edited: May 16, 2021
  10. Davey

    Davey Heavy Rotation: Chihei Hatakeyama - Late Spring

    Location:
    SF Bay Area, USA
    Yea, and the 1000R adds another set of windings offset on the other side of the PC board.
     
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  11. Oelewapper

    Oelewapper Plays vinyl instead of installing it on the floor.

    FWIW: When it comes to motors, the nomenclature of AC and DC is sometimes a bit misleading.
    Many DC servos for example are actually AC but run on DC because of built in circuitry that converts it to AC.
     
  12. JP

    JP Forum Resident

    Location:
    Brookfield, CT
    Yes all fairly academic. However you said the 'illustrations shown in the post above' show that it's 9 pole, while the illustrations didn't show magnetic poles but 9 coils, which is why I asked how do you know it's 9 poles? Also note that Technic's state the 10R motor is 12 poles and 18 coils. I understand it's slotless but for the purposes of motor geometry whether coils or slots it's the same thing with this design.
     
    Davey likes this.
  13. Oelewapper

    Oelewapper Plays vinyl instead of installing it on the floor.

    Makes you want to play some records, just by looking at that! :love:
     
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  14. formu_la

    formu_la A.I.

    Location:
    Toronto, Canada
    Brushless DC motor is a loose term. They are actually synchronous AC motors. DC voltage is not applied directly to the motor, but rather to the controller which generates AC voltage applied to the coils of the synchronous motor. The resulting magnetic field interacts with the permanent magnet of the rotor. The rotor always rotates at the same speed as the applied magnetic field, which makes it 'synchronous'. They always have a rotor position feedback (usually an encoder) , and it also acts as a speed feedback. Typically they are capable of not only precise speed, but also precise positioning. Not needed in a TT obviously.
    That is generic knowledge. I don't know all nuances of Technics motor design, but it looks like that's what it is.
     
  15. Ingenieur

    Ingenieur I love to travel, but I hate to arrive.

    Location:
    PA
    Here is the waveform
    DC biased AC
    at least for this model
    That likely makes it smoother, most power provided by DC, AC provides the rotating field.

    Some synchronous motors had a DC generator on the shaft that supplied the rotor/field I thru slip rings.

    motors? THE text
    http://prof.usb.ve/jaller/Fitzgerald.pdf



    [​IMG]
     
  16. formu_la

    formu_la A.I.

    Location:
    Toronto, Canada
    That is usually for very big sinc. motor. Typically used in compressors. Replaces permanent magnets.
     
  17. Ingenieur

    Ingenieur I love to travel, but I hate to arrive.

    Location:
    PA
    Yep
    But I don't see synchronous motors too often anymore. And I see x,000 HP all the time.
    Some had a DC power supply.
     
  18. formu_la

    formu_la A.I.

    Location:
    Toronto, Canada
    I see them every day at work :). Servo motors for CNC machines and automation. Exclusively synchronous AC motors these days. Prime AC supply converted to DC. DC converted to AC again to feed those motors. Fantastic devices. Can maintain nominal torque even at standstill unlike DC garbage 2-3 decades ago.
     
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  19. Ingenieur

    Ingenieur I love to travel, but I hate to arrive.

    Location:
    PA
    the slip of an asynchronous induction motor could not be tolerated in that application.
    :)
     
  20. ODS123

    ODS123 Forum Resident

    Location:
    Philadelphia, PA
    So this elevated discussion b/w all you brainiacs is very impressive. ..And I truly mean that. ..I wish I could follow along.

    But the question that really needs to be answered is: which of these technologies is distinguishable from the other?? ..What is the outcome data?

    I don't doubt that the GA/E measures better than at GR. ..Or that a 1000R measure better than a GA/E. ..But can a person who is unable to see the turntable able to distinguish one from the other? :)
     
  21. Kostas

    Kostas Forum Resident

    Location:
    Athens,GR.
    Assuming you have the same tonearms & cartridges* I don't think many can hear the difference from GAE/G to the 1000R in a blind A-B test. Phono stage, cartridge and arm/cartridge setup have a bigger sonic impact on what we hear from the turntable itself.

    *Two same cartridges is not easy to have, they are made by hand and have tolerances. To manage the same exact setup in two arms is also not an easy job. Everything a man makes is not perfect, the turntable is last centurys invention and by it's nature far from perfect. It's a needle on a non flat surface that's affected from everything around it.
     
    missan likes this.
  22. Pali Gap

    Pali Gap 'Why did you throw the Jack of Hea-arts awayyy?'

    Location:
    Bermuda
    If we're going to dive this deep, we may have truly lost our way lol...
     
  23. Oelewapper

    Oelewapper Plays vinyl instead of installing it on the floor.

    Yes, basically everything man made has a tolerance.
    You could conclude that because of tolerances no comparison can ever be made between any object, if you want to change only one variable... but that would result a slippery slope fallacy:

    Because if tolerances always have that big of an impact, it means measurement equipment is too inaccurate as well and we should doubt anything mankind has ever measured and all the knowledge based on that empirical evidence.

    It’s all about significance, not just when it comes to tolerances, but also when it comes to differences in performance.
     
    missan likes this.
  24. RPM

    RPM Forum Resident

    Location:
    Easter Island
    Ortofon used to sell "matched pairs" of the dj models.
     
  25. RPM

    RPM Forum Resident

    Location:
    Easter Island

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