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Is electronic speed control possible with a 240v motor on a Rega?

Discussion in 'audio' started by GruntPuppy, Aug 1, 2020.

  1. GruntPuppy

    GruntPuppy pfm Member

    Hello.

    I'm in the process of doing silly things to my Rega planar 2. One of the things I'm bumping my head against is finding some way of controlling the speed electronically, rather than changing the speed of the platter by moving a drive belt between pulleys.

    I suspect I'm having a senior google movement, because I can find nothing to do this. I can't be the first person to want to do this, do any of you know of a product that will allow me to do this?
     
  2. pocketkitchen

    pocketkitchen Registered User

    Heed Orbit 1 will do the job. Exactly what it's designed for.
     
    guydarryl and GruntPuppy like this.
  3. Vinny

    Vinny pfm Member

    Yes, but how smooth etc. the motion might be...………….

    Many moons ago, inline speed controllers for 240V drills were common enough.
     
  4. JemHayward

    JemHayward pfm Member

    May be worth doing the 24v motor upgrade first... I think 24v controllers may be easier to find.
    Other option would be to try a Naim Armageddon or DIY clone. I preferred the Armageddon (DIY) to my Lingo mk1 on my LP12 (240v). - EDIT this won't solve you speed change issue!

    I eventually built a "Meldano' PSU, and run a Papst 24v (Michell Gyro) on my Transcriptors Skeleton, though I run a larger pulley, and run the motor more slowly. Lots of options!
     
  5. Barrymagrec

    Barrymagrec pfm Member

    Drill controllers operate by phase angle switching of the mains waveform. This operates well enough on a commutator motor but would not be at all effective on a synchronous, or even asynchronous type.

    The Heed operates by providing a variable frequency drive waveform and so can vary the speed of a synchronous motor over a reasonable range.
     
    Arkless Electronics likes this.
  6. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Assuming a 240V synchronous motor then any number of units could do the trick. There are also DIY options such as the "Nigel's speed controller".
     
  7. hifi_dave

    hifi_dave Hi-Fi Retailer

    The 24v motor upgrade is a big improvement and then you can add a Neo. Has the benefit of being tried and tested.
     
  8. linnfomaniac83

    linnfomaniac83 I bet you can’t wheelie a unicycle!

    Yep, but I’d have thought you’d be better off selling the 240v deck and buying a used 24v model, unless you really want an “original” Rega deck.
     
    Durmbo likes this.
  9. GruntPuppy

    GruntPuppy pfm Member

    Thank you - exactly what I was looking for. Expensive box, though! If a second hand motor comes up on eBay (which they do occasionally) then that'll be a slightly more cost effective route, but this is firmly on my radar now. How I didn't find this before, I do not know.
     
  10. GruntPuppy

    GruntPuppy pfm Member

    Muahaaahahahaha!

    Sorry, so little of the deck is going to remain that I'm not sure it'll deserve the name "Rega". Subplatter and Bearing replacements are already here, dual belt conversion parts too, a new platter is on the way, I'm about to do an off-board motor conversion as well, if budget allows... after that, it'll be arm modifications, and finally plinth modification or replacement to think about. Finally the motor/speed controller (although the motor might get a minor tweak in the form of a thrust bearing).

    I really am having a ball with this thing...
     
    linnfomaniac83 likes this.
  11. linnfomaniac83

    linnfomaniac83 I bet you can’t wheelie a unicycle!

    Ah a proper project then! There are many options with regards to electronic speed control, the easiest is the Rega 24v motor kit and a TT-PSU or Neo, but there will be cheaper options.
     
  12. geoturbo

    geoturbo pfm Member

  13. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    With a 24V AC motor one could even use a left field option of using a >75W power amp to drive the motor and a PC derived low distortion sine wave as its input. Change speed or increment it up or down etc at the click of a mouse.
    I'll get my coat.
     
  14. linnfomaniac83

    linnfomaniac83 I bet you can’t wheelie a unicycle!

    You might laugh, a long time ago, I experimented with an MP3 player and an amplifier module, I recorded the sine waves from my signal generator in audacity... well it worked, albeit a little Heath Robinson!
     
  15. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    :) In the form I described, although Heath Robinson without a doubt, if should work very well:D Obvs although the amp needs to be 75W+ @ 8R in order to do the Volts it would only be delivering say 3W and should run pretty cool....
    If you have say a <0.01% THD amp and <0.01% THD sine wave from the PC, its frequency derived from the PC's quartz clock, that's a pretty low distortion and accurate TT PSU;)
    With a little ingenuity I guess you could use stereo channels of the power amp to drive each phase of the motor... and with the right sine generator app be able to generate the sine waves with control of relative phase and level to optimise any motor:) I'll bet its been done. it's not rocket science. A sound card, a pot for fine control of level, a £70-ish Chinese Behringer or similar 150WPC shit PA amp and you have one hell of a potential 24V AC TT PSU with every parameter adjustable at your PC screen:)
    Hmm.. some surplus 100V line transformers like almost every one must have laying around :)D:rolleyes:) could step it up so it works with "240V" motors:)
     
    djftw and linnfomaniac83 like this.
  16. Craig B

    Craig B Re:trophile

    Note that there are no 240V Rega motors. Prior to the 24V electrics, a 24-pole, 110V, AC synchronous motor was fitted for all markets; the difference being the PCB electrics and pulley diameter (the motor running at 250RPM on 50Hz, and 300RPM on 60Hz).

    There are two Heed Orbit models, as follows:

    Orbit 1 outputs ~110V, therefore, it comes with a PCB containing a single 0.22uF capacitor which replaces the Rega PCB and leaves the Rega mains switch out of circuit. As with Orbit 2, the Rega mains plug is replaced using a supplied IEC male plug that fits into a corresponding IEC female output socket on the Orbit 1.

    Orbit 2 outputs ~230V so is plug-and-play compatible with any ~110V output Rega PCB, and, therefore, leaves the Rega PCB and mains switch in circuit. With this model you simply replace the Rega mains plug with an IEC male plug that fits into an IEC female output socket on the Orbit 2.

    One particular Orbit 1 user did his own PCB install (late 80s Planar 2 with the original Motor Upgrade Kit installed) and decided to keep the Rega mains switch in circuit. He obviously couldn't resist leaving well enough alone and decided to hamfistedly pries the Rega thrust bearing off in favour of an aftermarket alternative:
    [​IMG]
     
  17. sq225917

    sq225917 Bit of this, bit of that

    Meldano speed controller and a 24v motor and pulley from Rega via your local dealer. Adjustable start up ramp, voltage, frequency and phase angle via a USB interface. Or nigels, or a number 9, or a neo...
     
  18. Craig B

    Craig B Re:trophile

    Add to the list the ISOkinetik ISOdrive 1 which appears to be a rebranded Heed Orbit 1 for £299.99 (vs. £395 for Orbit 1 or 2).
     
  19. retseldrib

    retseldrib pfm Member

    I have an old Rega Planar 3 which I’ve been using in lockdown after a service and new upgraded drive belt (glorified elastic band) and it sounds superb. The speed of the TT seems steady without any discernible pitch problems. I’m intrigued (genuinely) how upgrading the motor with the external NEO PSU will improve the sound? It’s either spinning at the right speed or it isn’t - correct?
     
  20. Craig B

    Craig B Re:trophile

    Hi @retseldrib,

    If you specifically search for 'uk mains frequency specification', your top hit is likely to be the following:

    "The GB mains frequency is nominally 50Hz. National Grid is obliged by its licence commitments to control the frequency within ±1% of 50Hz so it can fluctuate between 49.5Hz to 50.5Hz. However the normal operational limits are 49.8Hz to 50.2Hz."

    As your Rega motor is AC synchronous, it is the mains frequency that governs the speed (250RPM @ 50Hz), whereas, voltage governs torque. Ideally, the frequency should be spot on 50Hz, with the voltage in an optimum range that provides enough torque to overcome friction, whilst at the same time allowing the motor to run as quietly as possible. Typically, external supplies regenerate a near perfectly stable 50Hz (often quartz referenced), plus a preferred optimum stable voltage. Some, like the Naim Armageddon, don't regenerate the frequency (à la Linn Valhalla, etc.), rather they are intended to optimize voltage across the two phases of the motor for an optimum blend of torque vs. phase angle.

    The Heed units mentioned above have an output stability spec of 0.1% frequency shift with a max. 1% THD of the sinusoidal waveform. Other makes likely offer similar performance, however, I'm not familiar with the ones that list such. With the Rega Neo, the specified speed control step size of 0.01RPM would indicate a similarly high specification, by necessity (likely better).

    P.S. Keep in mind that, at 60Hz, the Premotec motor will turn at 300RPM. It wouldn't take much effort to calculate what ±1% of 50Hz would equate to as speed fluctuation range.

    P.P.S. Ok, call me pedantic. For every 0.5Hz deviation in mains frequency the motor speed will change by 2.5RPM; therefore, the permissible ±1% of 50Hz will allow a 24-pole AC synchronous motor to vary between 247.5 to 252.5RPM, which equates to 33.0 to 33.7RPM at the platter.
     
    Last edited: Aug 3, 2020
    retseldrib likes this.

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