Here's an excellent round-up of Leslie motor speed controls (used to convert older single-speed Leslies to dual-speed) on the market which was posted by MikeCasino to TheHammondZone.
(Best results when the motors, belts and rotor bearings are in proper working order --- clean, lubed and tensioned properly.)
No Soldering, using existing relay for a conditioned input.
Brand New product. Gated Pulse Modulation with zero crossover motor control in slow speed. Fast slow switching method, standard cabling, compatible with stock Leslies. Easy mounting location is inside the Leslie cabinet, using AC plugs (with color band identification) into two of the amplifiers AC sockets. Reverb socket for power and motor socket for control. This two speed Leslie motor control will convert any Leslie with single speed motors or dual stack with the slow motors disabled or removed. The use of stock DC motor breaking must be disabled or removed. The motor controller features a 122 style warm up cycle (12 to 15 seconds in tremolo speed) on power up and adjustable 16 slow speed choices by dip switch selection. Use of this two speed motor control eliminates the inductive load on the relay contacts reducing the probability for that switching Pop sound to be induced into the audio circuitry. Also when used on a dual motor stack system with the slow motor disabled or removed, service issues regarding the rubber tire wear, shaft alignment, spring and fiber washer replacement are completely eliminated. This product has its own transformer coupled power supply. Optically isolated motor switching module rated at 5 amps and with CE, RU, SA, DVE safety certificates.
Switching scheme: uses the relay in the amp.
Speakeasy Vintage Music is very proud to offer this Brand New product. This 2 speed Leslie motor control will convert any Leslie with single speed motors. The item features a 122 style warm up cycle & adjustable 16 slow speed choices. Installation is plug & play. This product is part of a new line from Caribbean Controls. Their design has 100% more slow speed torque then the other brands' kits. No programming required. Full installation instructions are included and all Carribean Controls products carry a one year warranty.
I purchased a two speed conversion unit from speakeasy to install in my Leslie Model 51. Installation was straightforward and the installation instruction quite clear. Installing this unit on any single channel Leslie should be simple enough for anyone with a little bit of electronic knownedge. Removing the brake circuit is not difficult but could intimidate you a little. The noteable exception to the installation instructions concerns two channel Leslies such as the 50c or 51. The kit requires a hot 120v outlet to opperate. On a two channel Leslie amplifier there is no accessory or reverb amp outlet as this chassis space is occupied by the stationary speaker output jack. I rewired the inner most motor outlet by removing the hot lead bewteen both motor outlets and soldering in a new hot lead wired directly to the fuse holder. The sonic qualities of the Leslie after conversion are fantastic. The chorale (slow) speed sound is a welcome addition to my old 51. _-Anonymous_
Brand New product. Gated Pulse Modulation with zero crossover motor control in slow speed. Fast slow switching method, non standard cabling, compatible with non stock Leslies using an amplifier other than a Leslie Amp. Easy mounting location is inside the Leslie cabinet, using AC plugs (with color band identification) into an AC sockets. This two speed Leslie motor control will convert any Leslie with single speed motors or dual stack with the slow motors disabled or removed. The motor controller features a 122 style warm up cycle (12 to 15 seconds in tremolo speed) on power up and adjustable 16 slow speed choices by dip switch selection. Use of this two speed motor control eliminates the inductive load on the motor relay switching contacts, therefore eliminating that switching Pop sound induced into the audio circuitry. Also when used on a dual motor stack system with the slow motor disabled or removed, service issues regarding the rubber tire wear, shaft alignment, spring and fiber washer replacement are completely eliminated. This product has its own transformer coupled power supply. Optically isolated motor switching module rated at 5 amps and with CE, RU, SA, DVE safety certificates.
Switching scheme: uses a 12 VDC signal to ground triggered by supplied detachable footswitch.
Speakeasy Vintage Music is very proud to offer this Brand New product. This 2 speed Leslie motor control will convert any Leslie with single speed motors. The item features a 122 style warm up cycle & adjustable 16 slow speed choices. Installation is plug & play. This product is part of a new line from Caribbean Controls. Their design has 100% more slow speed torque then the other brands' kits. No programming required. Full installation instructions are included and all Carribean Controls products carry a one year warranty.
Pulsed frequency controlled with zero crossover motor control in slow speed, fast slow switching method, standard cabling, compatible with stock Leslies. Mounting location is inside the Leslie cabinet, using AC plugs into two of the amplifiers AC sockets. Reverb socket for power and motor socket for control.
Switching scheme: uses the relay in the amp.
The Hamptone Motor Control performs this by synchronously switching the power on / off to the motors at precisely the correct intervals to achieve reduced speeds from a single speed motor. Power is never interrupted when current is flowing through the motors to provide quiet operation (no switching noise on AC power, i.e. fed into amp). It does not achieve this by varying current or voltage applied to the motor as these methods can cause motor damage.
Pulse Width Modulation is used in all modes. Brake or coast feature jumper selectable, order for one family type or the other but a dealer component swap will convert unit to other type, fast stop slow switching method, 40 selectable slow speeds, replaces mechanical relay, eliminates the 12AU7 switching tube, the .1mfd cap removal is required,standard cabling compatible with stock Leslies using the tremolo / chorale switching method but not compatible with stock Leslies using the tremolo / stop / chorale switching method in stop mode (the stock amp will still remain on fast when you have the switch on stop). Supports the EIS 3 mode operation. To use the stop function, a tremolo / stop / chorale switch is used in place of the tremolo chorale switch and a zener diode added to the switching circuit.
Switching scheme: Sourcing, (Standard), 0-8.5 VDC fast, >13.5VDC slow, and 8.5-13.5VDC stop.
The controller is designed to provide 2 speed plus stop capability for 22H and 47 single motor/single speed leslies. In addition, it provides compatible replacement circuitry for the speed change logic in the amplifier. PWM control of the motors results in a more accurate speed adjustment and results in the motors running much cooler in the slow speed mode.
As of late August 2008, the originating inventor passed away. This product might not be available unless someone takes on the business. A future update is possible.
http://www.bentonelectronics.com/MTCLogic.html for more info.Pulsed frequency control with zero crossover motor control in slow speed, Fast stop slow switching method, Replaces mechanical relay, Four selectable slow speeds, Standard cable, Not compatible with stock Leslies. Switching kit for 122 type (8000, 6122 kit ect.) not needed. Mounting on transformer studs of 147 / 122 amps. Other size transformers require a mounting bracket. To use the stop function, a tremolo / stop / chorale switch is used in place of the tremolo chorale switch and a a 220K resistor is added to the switching circuit for slow mode.
Switching scheme: Sinking (utilizes pin # 5 to control switching) 0V (closed) fast, open stop, 220K to Ground is slow.
Use with single speed Leslies or on fast motors, 3-speed (off/slow/fast), Low voltage signal switching, eliminates the old mechanical relay, Uses the standard 6-pin cable, Mounts inside 122 or 147 series power amps, Select speed with a standard 3-position switch, 4 Selectable slow speeds.
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