Leslie speaker rewiring help

Discussion in 'Amp Tech Center' started by Steve77, Aug 31, 2020.

  1. Steve77

    Steve77 TDPRI Member

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    Looking for help wiring speed control in a Leslie.

    Picked up a Leslie Orpheus 25. It’s a really basic Leslie and seemed perfect to turn into a guitar speaker.

    It has no amp so I just ran the speaker to a 1/4 inch jack making it an extension cab with a rotary speaker.

    Next I ran ac power to the motor through the control box which contain the relay and brake coil.

    Worked perfect.

    The exterior was a bit beat up so I decided to cut off the top foot or so of empty space.

    The now compact cab is much lighter and still sounds fantastic.

    The only draw back. It’s a single speed motor. So only fast speed.

    I’ve got a two speed motor on it’s way, but I’m a little unsure how to wire it in.

    Leslie seems to use relays for all the motors and I’m a little unsure why.

    The motors run 120ac. Why not just use a switch to go from the fast motor to slow?

    The idea of a foot switch comes to mind. I have a switch that would work perfect it’s rated at 3A at 120 volt. I’ve read the motors run just under 1A. That seems like it would work.

    The relay in mine seems to be using 120 Ac to switch the relay to allow 120 to the motor. This seems to make it unnecessary. Or does this have more to do with keeping high amps off the switch and longer wires? I’m sure I could rewire the relay to switch in between slow and fast motor, but I’m trying to understand what the point would be.

    As well it’s easy enough to get an on off switch but I’ve never heard of anyone running ac volts through a foot switch. Is this a foolish and dangerous thing to do?

    I suppose I could just plug it into a power bar and turn the power off that way and put the speed switch on the speaker cab. I would never really be changing speeds mid song.

    anyone have any experience wiring Leslie speed controls that could offer any advice?
     

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  2. schmee

    schmee Doctor of Teleocity Silver Supporter

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    I'm not sure why either. But I'm guessing to keep high voltage from a long wire and possibly shocking someone? I made one from inside a small Lowry organ that didnt have an amp, and just used a two way Leslie switch for speed like the organs use.
     
  3. Jon Snell

    Jon Snell Tele-Holic

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    If it has a mains powered motor, why not use a speed controller, (light dimmer). A photo of the motor may help.
    The control can be fitted on the rear of the cabinet but must not go to a foot pedal!
     
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  4. Peegoo

    Peegoo Friend of Leo's

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    I built a Leslie cabinet using a small Leslie rotor and motor from an old Lowry organ. The motor is a shielded-pole (brushless) AC motor, and I used a rheostat that provides infinitely-adjustable rotor speed. Get one with a built-in switch.

    Note: the type designed for light dimming will not work because these little motors require full-wave AC. The reason dimmers don't work is most of the type available today use a MOSFET to chop up the AC wave form; this can cause the dimmer and/or motor to overheat. It's also the reason why dimmer switches don't work with fluorescent lighting; they also require full-wave AC.

    This is the rheostat I used; it's designed for shielded-pole blower fan motors. And it's simple to wire: hook it up in series with the AC power and the motor.

    https://www.amazon.com/gp/product/B07P9DR7SN/?tag=tdpri-20

    Like this:

    [​IMG]

    Here's a vid of me testing the rheostat with the motor.



    This is the finished project.

    [​IMG]
     
    Last edited: Aug 31, 2020
  5. dogmeat

    dogmeat Tele-Afflicted

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    I've built one out of parts too. I put the AC in a foot switch but it's single speed, so its just off/on. I have two buttons on the pedal, one switches from the amp's speaker to the "Leslie" speaker, and the other is on/off for the motor. it works fine.

    I have second one under construction (on hold for the past year due to house projects), This one is two speed & I'm using relays. one for on/off and one to switch motor speeds. I wired the relay control circuits to the foot switch. AC straight to the cabinet to power the motor relays and a transformer to get 12 v for the control circuit. 12v to a rectifier for DC relays

    one reason to use relays is the inrush current on motors. motor runs on 1 amp when running but it draws 5 amps when you first turn it on

    the speed controller Peegoo posted looks interesting. but like he says certain types of controllers won't work. all single phase AC motors need a second phase just to get moving. the "shaded" pole makes that second phase in these motors... it is created by cutting a slot in the frame and putting in a wrap or two of heavy copper wire. the main flux field cuts across that wire and creates the 2nd phase. thats why it wants full wave. chopping the sine up too much creates too many discordant magnetic fields
     
    Last edited: Aug 31, 2020
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  6. Paul G.

    Paul G. Friend of Leo's

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    Reason? To keep AC out of the remote switch and wiring.

    Personally, I think that's a good idea.

    If you really don't think you'll be changing speeds on the fly, just put a suitable switch on the cab.
     
  7. Bill Moore

    Bill Moore Tele-Afflicted Silver Supporter

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    I have a variable speed controller on a ceiling fan, why wouldn't that work?
     
  8. knockeduptele

    knockeduptele Tele-Holic

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  9. knockeduptele

    knockeduptele Tele-Holic

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    do you have a pic of the Motor?
     
  10. Collin D Plonker

    Collin D Plonker Tele-Afflicted

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    Seems there has to be a way to hook a rheastat to a foot pedal.
     
  11. Steve77

    Steve77 TDPRI Member

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    Peegoo I’ve gotta check out that rheostat. I’d never heard of someone using that. unfortunately I’ve already committed to the dual speed motor, but I could always try that later too.
    dogmeat, I’m glad someone else has done the on/off foot switch too. That’s really all I want out of a foot switch. the relays I have are unusual. They run completely off Ac. But from what you said dogmeat, it has more to do with the current draw as it starts. Makes sense.
    well for the time being I’ll rewire the relay so it is slow or fast. I will run a switch to the back of the cab (for now) and I’ll try doing a foot switch for it later. I think if I run into any problems I may do as Paul G said and just find a strong enough switch and wire it to the back of the cab. I really can’t think of a single song I know that switches speeds during a song.
    thanks guys for the help
     
  12. Steve77

    Steve77 TDPRI Member

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    Oh sorry those last ones came as I was typing.
    No unfortunately the motors being shipped soon. I’ve got a single speed motor right now.
    I was going to get rid of it, but with peegoos suggestion I may hold onto it and try his rheostat idea.
    I thought of using his rhetostat and seeing if I could install it into a crybaby shell I have. I may give it a try later.
     
  13. Steve77

    Steve77 TDPRI Member

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    Frankly I really should have done the forum first instead of just buying a two speed motor. oh well, it’s done now
     
  14. Peegoo

    Peegoo Friend of Leo's

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    There is. It's called a sewing machine foot pedal ;)

    Another one that will work is the foot pedal for a Foredom (rotary shaft tool used by jewelers, modelmakers, me, etc.) or one of its clones.

    The only caveat is these types of pedals have a return-to-zero spring that shuts off the motor when you remove your foot from the pedal. That could be disabled and a clutch or other drag-inducing facility could be used to hold the pedal in the desired position when the foot is removed.
     
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  15. dogmeat

    dogmeat Tele-Afflicted

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    no harm in using AC relays. they work fine

    one of the charming things about the Leslie is changing speeds... the enhanced Doppler effects as it winds up and slows down. old school Leslie users used the speed shift as well as the Off/On to create these shifts for effect... often as a wind up (or exit) to a solo. even if you only have Off/On at the pedal it can be used to create these effects. in the Off position the cabinet makes a way different sound than the amplifier's cab. as I said, I made my pedal switch between the two
     
  16. Viejo

    Viejo Tele-Afflicted Silver Supporter

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    Old Sewing Machines used to have variable speed motors controlled by a rheostat in a foot pedal like an auto throttle. There have to be some laying around resale shops or auctions
     
    Last edited: Sep 1, 2020
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