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Leslie 16 Motor Speed Adjustment

Discussion in 'Amp Central Station' started by ojaverde, Feb 17, 2011.

  1. ojaverde

    ojaverde Tele-Holic

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    I just read in an Ebay description for a Leslie 16 that the speed of both motors is adjustable+/- 20%. Can anyone confirm this? And if it is true does anyone know how to do this?
     
  2. eugenedunn

    eugenedunn Friend of Leo's

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    [​IMG]
    Hey Ojaverde......long time! I guess the last time we conversed, the topic was about Leslies.....we gotta stop meeting like this! (^_^)

    Are you saying the eBay listing says that there's a "hidden" adjustment control somewhere near the 2 motors?! I have played around with the belt tension and of course toggling rapidly between the slow & fast speeds to vary the total effect.....but AC motors generally don't tolerate large swings in voltage to control revolution speed.....the correct way to vary the speed is with some kind of frequency modulation of the AC voltage...... that pretty much eliminates the use of a variac (which I had very conservatively tried to do, a long time ago...)

    I haven't found anything to do that with.....have you?
     
  3. eugenedunn

    eugenedunn Friend of Leo's

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    Speed adjustment possible with 2-speed Leslie 16 or 18?

    Speed adjustment somewhere around here? (Leslie 18 front baffle showing the slow and fast AC motors)
     

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  4. ojaverde

    ojaverde Tele-Holic

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    I don't know what they were talking about. That's why I was asking here at TDPRI. I agree that it's probably not possible to vary the speed very much unless you are changing the belt tension?
     
  5. eugenedunn

    eugenedunn Friend of Leo's

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    Here's an interesting post I found regarding the 2-speed motor adjustment. While it doesn't address speed adjustment specifically, it does provide some additional info on motor adjustment beyond just belt adjustment.

    Ok, if it is a 2 speed Leslie there is an adjustment screw between the fast motor and the slow motor. Many times, the motors are out of alignment which causes the slow motor to run poorly or not at all. This screw moves the armature of the slow motor closer or farther away from the clutch wheel. The clutch wheel is the flat round wheel with the rubber O ring around the edge. More often than not with Leslies, it's a combination of factors that cause problems. As earlier stated by WildBill, the armatures probably need oil. However be careful what kind of oil you use. The best is the type used in Hammond organs and is available through a various places such as the Organ Service Centre, Goff etc.
    You can always use sewing machine oil as it's light enough and won't break down. If you have any further questions, please email me at www.toneonwheels.com
     
  6. eugenedunn

    eugenedunn Friend of Leo's

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    Here's a comment on the use of a Variable Frequency Drive:

    "A commercial VFD ( variable frequency drive ) scales the the AC
    voltage as well as the frequency to keep the motor current constant.

    Output frequency typically varies from as low as 0.1 Hz to 300 Hz - so a very
    wide range. The high end is more of a worry as the motor may overspeed and
    be damaged by high centrifugal forces.

    A Google search will turn up dozens of them on offer - starting with units
    rated for 150 watts and single phase"
     
  7. phillip lee

    phillip lee TDPRI Member

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    I just increase the slop in my belt so it will run slower.
     
  8. eugenedunn

    eugenedunn Friend of Leo's

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    Yeah, the belt tension thing works better for the higher vibrato speed, but then, the slow chorus speed gets a bit too sloooooow. ;)
     
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