Leslie 16 cabinet customizing question...

[greycatlost]

Hello,


Here is my question/dilemma.

I have a Leslie 16 that I bought off of the sax player for the Dave Letterman Show(random fact). I love the way it sounds, but feel it’s limited. As you know, it has only two speeds, and two different motors to control it. I would like to put a different motor in it, preferably dc, that is variable speed, and be controlled by a pot in an expression or volume pedal. Essentially, the control of a Univibe through a real Leslie cab. I can’t seem to find a motor, ac or dc, that can be controlled between roughly 70 rpm and 330 rpm(the two different speeds on the original motors). Am I crazy for thinking this? It seems it would be pretty straight forward, but I’m at a loss.

Any insight or advice would be much appreciated.

[JJGross]

Maybe I'm way off here, but wouldn't a dimmer type control as used for a ceiling fan work for this? They're specifically designed for controlling the speed of 115vac motors from barely moving to wide open. You wouldn't even need to use both of the Leslie motors to do this - just the fast one.

I'd think if you could mount one in a treadle it would work. Probably wouldn't fit in an old wah pedal, but if you can fabricate some steel plate to a box with a rocking pedal on it, the mechanics would be pretty much the same. Maybe an old indistrial pedal switch housing or a speed control from a sewing machine? Heck, maybe a sewing machine speed control would be just what you need now that I think about it. Maybe that's what I need for MY leslie. ;D

Cheers,
- JJ

[greycatlost]

That might be the ticket.

Maybe I'm overthinking this whole process. Your idea might be the best way. Thanks for that!
My only concern is the idea of having a/c current running to a pedal, especially while on stage outdoors, etc. I suppose if I insulate and sheild it properly, it wouldn't be too much of an issue.
I'll give it a whirl and post later on the outcome. Crossed fingers....

GCL

[JJGross]

Yeah, the out-front AC is something that I'm not wild about either but it works for industrial applications. I know there are industrial treadle type AC speed controls available at places like Mouser, but be prepared for sticker shock - they're not cheap. My personal solution for this is just to use 5vdc relays for switching between speeds as well as on-off for the motors + another relay to switch the speaker itself on & off. I'll start another thread with those issues (impedance, noise & all that). This way even though I don't really have complete speed control, I'd have only 5vdc coming through MIDI cables out front and all my AC will stay in the backline. After all, the whole 'Pedalsnake' product is nothing more than a MIDI snake at twice the price with some very expensive connectors/converters to attach everything on both ends of the snake.

I'd think AC out front would be ok as long as you use a watertight switch box, watertight sealed cable connections and possibly a lot of silicone goop of whatever kind you fancy. Outdoors would require some pretty rugged safety precautions built into it, but even indoors there's all that flying beer.

"Chicken wire ...?" ;D

If you really want to get wild with this concept, use a rheostat out front with low voltage power connected via a MIDI cable to a stepper motor in the Leslie cabinet on another rheostat controlling the AC to the Leslie's motor. You wouldn't even need to have the power out front since you could use 3 of the 5 MIDI connections for control, and the other 2 for phantom power. Let's take it WAY out there and say you're going to use a wireless MIDI setup so you don't even have to plug it in, though you'd now need low voltage DC power out front for the transmitter. As far fetched as that might sound, they're making car throttle controls with stepper motors. If they're confident enough in the failure rate to put it in a car that should last at least 20 years and commonly go to 300,000 miles (half-million+ km anyone?), I'd think it would be OK for a Leslie motor control. Far less of a safety issue if it fails in a speaker on stage than under your hood at freeway speeds.

Cheers,
- JJ

[seven]

Just thought I'd share some pics of my Leslie 18 restoration with "new" JBL D120-F:

[IronmanMC]

It seems to me that a servo would do the trick.

[Enzo]

Sewing machines have speed pedals they plug into, and they are not expensive. I secomd that idea. Those industrial controls like Mouser sells will set you back a month's rent.

You may not care, but part of the Leslie magic is the inertia effect as it speeds up, and especially on the two way units wher the horn changes speed faster than the larger woofer baffle does.

[Regis]

I have a Leslie 16, and have scratched my chin from time to time about the speed issue.

For one thing, if you are using the regular slow/fast switch that comes with it, you already have AC out front. Just try putting the switch near another pedal that is carrying your guitar signal and you will hear the hum.

Like JJ I thought of using relays back behind the cab and controlling them with a DC voltage at switches out front.

Variable speed would be nice but for me I would just like a "Medium speed" between the fast and slow the unit already has.

How could this be done? Maybe a Zener to soak up the voltage? Or some sort of hardwired SCR like the dimmer circuits have?

[IronmanMC]

If it's an AC motor, a quadrac fan speed control (looks like a dimmer but made especially for AC ceiling fans) will give continuous speed control. If you swap out the built in pot for several switchable pots, you can have multiple switched speeds.

If it's 120 volts DC, add a full wave bridge rectifier to the quadrac speed control.

Low voltage DC can be adjusted in many ways.

Quadracs, like triacs and SCRs, are noisy, and you'll probably need some filtering and buzz reduction.

It's kinda heavy and overkill, but a variac would do the trick. I would use it to try different voltages, then design something from that.