DIY Rotary Speaker Motor

[Magic Smoke]

Any recommendations for a motor and controller for this build?
The author of the article does not specify and will not answer emails.

https://www.premierguitar.com/articl...rotary-speaker

[Chuck H]

The guy doesn't give much info on the motor but to say DC brushless. Without a HP rating it's hard to suggest something. The size of the motor will have a large affect on how fast it starts and adjusts to speed control (if that will be important). But too large would be noisier. I would think something like .25hp would spin a Styrofoam drum well enough and not be too noisy? Between the motor and speed control you'll be into parts for over a hundred bucks (if you shop bargain products) unless you can find something used on e*bay and takes yer chances.

[nosaj]

The guy doesn't give much info on the motor but to say DC brushless. Without a HP rating it's hard to suggest something. The size of the motor will have a large affect on how fast it starts and adjusts to speed control (if that will be important). But too large would be noisier. I would think something like .25hp would spin a Styrofoam drum well enough and not be too noisy? Between the motor and speed control you'll be into parts for over a hundred bucks (if you shop bargain products) unless you can find something used on e*bay and takes yer chances.

If I really wanted one I'd go to craiglist and post an add for free organ pickup. You will then have all the parts for a leslie as most of the organs have them.
DIY or reuse whatever you wanna call it . I call it cheap
All the ones I've torn down were ac motors with a hall effect switch on them.

nosaj

[Chuck H]

Those motors were probably AC because that's what was easiest to incorporate into the whole design or what was cheapest. Possibly just what was available.?. But DC brushless should be quieter both in operation and in EM heard by a guitar pickup in close proximity. Of course it's more complicated to make it variable speed. With the AC motor you could just use a lamp dimmer.

[Enzo]

A zillion HAmmond B3s with Leslie cab got along for decades with fast and slow. No need for variable. And circuits couldn't be simpler: a switch.

[g1]

Also, I think part of the signature sound is the ramping up/down with the speed switching. You would not get that with variable.

[Enzo]

Not only that, the horn and the woofer ramp up and down at different rates, not in lock step.

I agree, the transitions can be more interesting than a steady speed.

[J M Fahey]

I used to make own design "Leslies".
The full Monty: separate Woofer and Tweeter, wooden bass rotor and metallic treble horns (made with truck air powered blast horns, go figure) , but most important: all mechanical, separate low and high speed motors with an automatic clutch ... same as original Leslies.

Low speed electric motor was sourced from a roof hanging fan manufacturer, and high speed one was a smaller one, using the Leslie trick of making a special "armature/frame" , where the squirrel cage core was partially outside the winding when non energized, but which rised into proper position when powered, winding current acting as an electromagnet.

When in working position its ¿axle? could touch a driving disk edge, coupled by a rubber grommet ... similar to **old** style cheap record changers, where rotating platter was pushd by a rubber edge driver .

My partner cared about the mechanical stuff, including sourcing motors, while my job was the Audio and switching section.

Incredibly market demand (it was the Deep Purple era) was large enough that 3 small "companies" could live by making them under basically garage shop conditions

Today "globalization" kills any and all attempts to manufacture anything outside China.

EDIT: didn´t keep pictures of "ours" (RMS brand) but this is one of our 70´s competitors:

[crochambeau]

Any recommendations for a motor and controller for this build?
The author of the article does not specify and will not answer emails.

https://www.premierguitar.com/articl...rotary-speaker

There's not a lot of mass to a chunk of styrofoam which is the only moving part, so I doubt you need to get crazy with power.

I'd probably go with a brushed motor like the XD-3420 to save some cash, though there are brushless two wire DC motors out there it turns into a slog really quick since there's a lot of high RPM stuff that will fall flat on its face when PWM'd down (and I'm guessing the noisy gear reduction used on screwguns/etc. would be objectionable) and pulley noise will probably be louder than brush noise. Maybe something like the ZYTD-38SRZ-R? That might be pushing the envelope in that it's only rated at 7 watts, but again - styrofoam.

I'd go for something in the 25 watts and up range to start, and probably just live with brushes for budgetary reasons.

[nosaj]

I only suggessted the free organ route cause that gives you All the parts for the price of gas. An what do you have to source after that?

nosaj

[crochambeau]

I only suggessted the free organ route cause that gives you All the parts for the price of gas. An what do you have to source after that?

nosaj

It's true you'll wind up with a potentially functioning unit or at least the hardware going this route (though organs are heavy and a PITA to move). That won't necessarily get you the DC motor though, as all the ones I've seen are AC inductance motors. Probably not a big deal in most applications, though I've seen plenty of talk in trying to remove as much AC source as possible from a room for recording reasons - so I figured the DC motor aspect was firm design criteria.

[nosaj]

It's true you'll wind up with a potentially functioning unit or at least the hardware going this route (though organs are heavy and a PITA to move). That won't necessarily get you the DC motor though, as all the ones I've seen are AC inductance motors. Probably not a big deal in most applications, though I've seen plenty of talk in trying to remove as much AC source as possible from a room for recording reasons - so I figured the DC motor aspect was firm design criteria.

Guess you never heard a b3 recorded. No noise I can heard. Just glorious organ.
Nosaj

[crochambeau]

Guess you never heard a b3 recorded. No noise I can heard. Just glorious organ.
Nosaj

No, I've heard plenty of B3 recorded, I just opted to adhere to the criteria laid out in the first post is all. It was pretty straight forward: looking for a brushless DC motor capable of spinning the Leslie drum.

[nosaj]

Pretty much moot anyways, this poster seems to start a thread with a single post and never a second post in the same thread.
nosaj

[Chuck H]

Funny... All the ads on the bottom of this page (on my display anyway) are electric motors at e*bay. I looked at a few this morning when I posted here.