rotary speaker

did you tried to make any kind of homemade rotary speaker? any idea how it is doable?

As in a homemade Leslie? I've had a project on my things to do for what seems like forever. Basically you could go many different routes but what a lot of people do is feed a signal into a speaker that's run into a bass rotor or cheese wheel. Many gutted Leslie parts such as the lower rotor and motors can be found on ebay. The problem is most are only single speed motors and to get the slow chorus that a lot of guitarists enjoy you need a dual speed version.

My up-and-coming project (if it ever gets finished) is similar to the Motion Sound Pro method were I'm using the Leslie horn and treble driver, power amp, crossover, and a Leslie simulator effect only for the low frequencies out to a guitar amp.

The reason is that low frequencies act as a tremolo effect when ran into a bass rotor. The highs act as a Doppler phase effect. Basically you have two effects going on simultaneously. Since the lows are only creating a tremolo effect there's not a whole lot lost by running the lows into a MI amp for instance because they can do the job of LF amplitude modulation there very well. The highs are where you have the problem. Trying to simulate the actual phase Doppler effect and the rotating horn accomplishes this very well.

Why bother? Personally I prefer running guitar through the Leslie's that have the horn/bass rotor combination. There's a degree of separation with the two effects going on separately that I don't get as much with the single wheel types. Also running keyboards through a single wheel just doesn't do it for me at all. You could also run the rotating horn on a DC servo motor that could be setup for preset speeds or made variable via a "expression" pedal. To get both the horn and the bass rotor sim to work hand in hand you would need relays and use of LDRs. In the end you would have a very portable and very realistic sounding Leslie effect.

I built my first rotary as a kid in 1960. I put a car speaker in a small box and mointed it on an old turntable. One speaker wire connected to a washer was heald tightly to the spindel. The second wire went to a tin can top on top of the box. A coat hanger provided the contact. The cram of the metal turntable was the ground to the inside wire.

The thing actually worked pretty good. I think I had two running for awhile.

If I were to make one now I'd use a styrofoam or plastic drum with a slit cut. Suspend it over a stationary speaker and use a motor to rotate it. maybe even a 5 gallon can and a 10" speaker.

The only reason I havent is because I have a leslie simulator that works pretty good and the thing will speed up and slow down like a leslie. I used a dan electro rockey road and put a jack for an external switch. The seitches on the box were too small. I use it in my guitar chain all the time.

Sounds like an interesting project. AES has some Leslie and Hammond parts.

Thanks for the advices. I will try to start this project and i let you know how is going on. If you know some good books (or websites) about rotary or lesley speakers, please let me know.

bests,

This one has nice pictures of a DIY Leslie, nice picture of the inside of a Hammond as well:

http://www.mantor.info/Hobbyhjornet/DIY_leslie_speaker/DIY%20Leslie%20Speaker.htm

When I was a kid, my grandmother had an organ and leslie in our house. I eventually figured out how to run the guitar though it. It just had two small speakers mounted at opposite ends of a bar that rotated.

I am interested to hear about your project.

I always wondered if it was important to sync the hi and low frequency modulations. From looking at the link I guess not.

To get both the horn and the bass rotor sim to work hand in hand you would need relays and use of LDRs. In the end you would have a very portable and very realistic sounding Leslie effect.

I'd suggest doing the control a'la motion sound -- hall effect sensors and SS motor control.

I've had a couple of their products, but never had occasion to tear it down, but (I think I glanced at a service print) I am under the impression they are using PIC to run the show

Hi, I am 3/4 of the way through a custom Leslie project, it's intended use is mostly for keyboards. The world-wide king of all homebrew Leslie threads is here on organforum.com

It covers a couple of years, has participants from several continents. It outlines details of several successes, and what didn't work. It is also a great education about Leslies in general. Here are some base point about Leslies.

There were over 200 models of Leslies made. The most famous ones are the 147 and the 122. Captain Foldback has a good list of the main ones. This is a frame from his regular site, a treaure trove of Hammond and Leslie info.

A real Leslie is a combination of the light plastic horns, attached to a treble driver, and a 12" or usually a 15" speaker. The speaker is fixed, and blows down into a wooden rotor. The horns and the rotor spin in opposite directions, are not syncronized at all. The horns weigh 7 ounces, the wooden rotor weighs just short of ten pounds. They spin up/down at differing rates.

In general, DC motors, vari-speed fan motors, or sewing machine motors are more trouble than they are worth. People have gotten them to work, but part of the Leslie sound is the ramp-up/down sounds, and the rates are closely associated with the weights of the horn/rotor assembly. They have cloth belts in pulleys that are intended to slip, and that is hard to replicate.

The real magic of a Leslie cannot be heard on any recording, nor heard at any big concert. Stereo micing a Leslie cannot reproduce the amplititude modulation and phase modulation of the horn/rotor spinning in opposite directions, splashing it around the room. The first time you are physically near a real Leslie with an organ playing through it, it can be quite dramatic.

Also, keep in mind, that the original Hammond organs had bass pedals, and at the top end would not put out but about 6.5khz. The famous rock and roll ones, 147 and 122 had 20 or 40 watt tube amps. Leslies have a 6, 9 or 11 pin input, that you cannot just adapt to a 1/4" jack. You can get special preamps to do so, but they are USD$200-$300.

A Leslie has an 800 hz crossover in it, so even if you get a suitable preamp, the horns will be wasted if you are longing for the Stevie Ray/Cold Shot sound. A high E on a guitar is about 329 hz. An octave higher at the 12th fret would be about double that, or just under 660 hz. Except for a few harmonics, almost nothing will make it past the 800 hz crossover into the horns for the real Leslie sound. By the same token, some modern keyboards will sound dull through a Leslie, because everything above the Hammond's rather lo-fi response of 6.5khz is simply not heard.

That link to the Norwegian guy's project is famous among DIY Leslie guys. Building your own cabinet from scratch is a huge undertaking, you need to be a serious woodworker to do so. The slots are very difficult to do like Don Leslie did. Also, building the spinning rotor from scratch is a very delicate project. Many/most home-brew rotor guys have wobbly things, that slowly tear themselves apart.

Many organs have a lessor Leslie inside them. Sometimes these are a one-speed, "on or off" Leslie, instead of the traditional 2-speed. These often have foam rotors, it's lighter, cheaper to make, and they could use cheaper motors. You can find these on Ebay easily, usually $40-$50. They can be a good starting point for a guitar-based Leslie, because you don't need the horns. They have a frame with the motor, bearings and rotor all in one piece. Here is a guy (he is a regular on organforum.com and quite a fanatic) that outlines converting an internal Leslie to a cabinet

A very good find for a guitar Leslie project is a Leslie 120. This is a passive cabinet (no amp), with a 12" speaker and a foam rotor. It's fairly easy to put in a regular 8-ohm (or whatever) guitar-type speaker in it. This guy outlines refurbing a 120 for guitar. This has a nice Leslie-appearing cab, though there's plenty of empty space inside.

There are a lot of lessor Leslies that can be had for little or nothing. Byron of Valhalla Woodworking makes excellent reproduction Hammond and Leslie cabinet parts. Of particular note are his authentic 147/122 shelves. If you are a moderate woodworker, you can often find an oddball Leslie for little or nothing, modernize the guts, put in a new shelf, and have a great Leslie for a fraction of the price.

More home-brew Leslie stuff. Steve Cyr makes a lot of custom guitars and basses. That would make him a pretty good woodworking kinduva guy. He embarked on a very cool custom Leslie project with a lessor cabinet. Aside from the large realities of making new slots (not louvers) in the cab, he took an interesting aside from the original Don Leslie design.

An important difference on his project, is that he has a Hammond A organ, that already has been modified to present a line level output instead of a speaker output. There are no 6/9/11 pin Hammond connectors involved, he had a 1/4" jack. He could plug nearly any keyboard (or guitar, with a preamp) into this and have excellent results.

Instead of a fixed 800hz passive crossover (which in the original Leslie configuration is what takes speaker output, peels off above/below the crossover point and sends it to the appropriate speakers) he used an active crossover with line levels. This makes it a bi-amped Leslie! The active crossover keeps it all line level, and then goes to an Alesis RA-100 solid-state amp. This has the advantage of quick and easy balancing of the horn to speaker levels.

With a speaker level crossover you can change the horn/rotor volumes by playing with different values of coils and caps, but with an active crossover, you have two easy knobs to turn. I have an Alesis RA-100 (really about an 80 watt stereo amp into 8 ohms), it is a nice (now) older studio reference amp. Unlike the original 147/122 tube amps, it won't howl if you crank it up. It stays C-L-E-A-N. If you upgrade the horn driver and speaker from the original Leslie configuration, it also can be quite a bit louder, if need be.

Steve Cyr's idea originally appealed to me, because as a home recording guy, Line Level Is King. There still is nothing that exactly compares to a red-hot 122 tube amp on 11. But, I would like to be able to plug other things into a home-brew Leslie, not just a Hammond.

On the Building Your Own Leslie thread mentioned earlier on organforum.com, there are several that have used bi-amped Leslies with good success. I know that it is a very, very long thread. It's 91 pages of posts, keep reading.

Stay tuned.

WRGKMC, it sounds like you invented a Mercotac connector that was used in the Rotosonic drums in some Leslies. A Rotosonic drum had small 5x7 or 6x9 speakers. The drum and the speakers rotated. To avoid winding up the speaker wires, they made something similar to what you did, only they used Mercury for the contact. They had tried brushes, like a generator or alternator uses, but it induced noise. "Real Leslies" (this term constantly dilutes, throughout this post) have a fixed treble driver that blows up into the spinning plastic horns, and a fixed 12" or 15" speaker that blows down into the spinning wooden or foam rotor.

That last link is part of a huge resource for all things Hammond, the Hammond Wiki can also be a few days of reading. Like any Wiki, it is not all the official gospel truth, but it's all there. Somewhere.

Another note on speeds, and the benefit of a custom active crossover compared to fixed 800hz crossover.

As mentioned, very little of most guitar-pitched things will make it to the top half of a fixed 800 hz crossover point, to make it into the horns. To clarify a bit, every sound we hear has higher (and lower) harmonics than the basic note (fundamental frequency). In the case of a guitar played through a clean Fender amp (for example), there can be lots of "sparkle", that are little high shimmery harmonics that are higher than the mentioned 630 hz. They can certainly make it to the horns. This is why an active crossover can be very cool.

A low E on a guitar is about 82 hz, the 12th fret of a high E is about 630 hz. All Hammond organs had pedals (too lazy to look those frequencies up) to play bass, and a top range of about 6.5khz. An active crossover could let you make a better guitar-type Leslie than anyone (including the Fender Vibratone, which was a re-badged Leslie 16 or 18). Instead of running a guitar through an antique Hammond-type Leslie, in which the vast majority of the sounds will only be heard in the speaker, and very little bit in the horns, an active crossover will let you slide that crossover point, to better suit a guitar. Or bagpipes, or whatever you are wanting to sling around the room.

I suck at math, but if you picked somewhere approximately in the middle of 82 hz and 630 hz, set your active crossover for that, then you could have a Leslie that pretty accurately puts about half into the horns, and half into the speaker. What would this sound like? I have no idea. The Fender Vibratone/Leslie 16 only had a single speaker, blowing into a foam rotor. It was mounted sideways, to spin up and around instead of a more conventional Leslie's spinning horizontally. To my knowledge, nobody has manufactured a dedicated 'guitar leslie' with crossover points, and horn/rotor drivers optimized for a guitar. Again, the original horn/speakers for Leslie were chosen for an organ's frequency response, not a guitar's. In addition, they are usually 16 ohms. This is another reason that a custom Leslie can be cool, to offer more options.

Another note on speeds, and why tradition is good. Normal is what you are used to, that doesn't necessarily make it right, or better. The 'regular Leslie' had fairly consistent speeds, even across their 200 differing models. Some models only had one speed, many had two. The horns often had a three-position pulley. You could move the cloth belt to the different sizes, to give a faster/slower speed. In nearly every Leslie any of us have heard, the speeds are mostly standardized to 30-42 rpm for slow, and 300-390 rpm on fast. The wooden/foam rotor never weighs the same as the 7 oz plastic horns. When they spin up/down, the horns always get there first, the rotor always lags behind. This, coupled with them spinning in different directions is what we think a Leslie sounds like.

What if your fast speed was 500 rpm? or 600 rpm? It would get a lot more warbly, and sound different. That doesn't mean it's wrong, but it won't sound like "A Leslie Should Sound". There is lots of room for experimentation. Yet, this is why the majority of people using custom motor arrangements don't get the 'The Leslie Sound' (if that is what they want). A sewing machine motor, or a DC motor with varying voltage can never directly replicate the slipping belts, and weights of the original equipment. Again, that doesn't mean it's wrong. If you want a traditional Leslie sound, you have to have both horns and rotors ramping up/down in their own independent ratios that more or less match up to the Hammond organ versions.

Here's another area for experimentation. There's no reason that digital controllers could not control a DC motor, with the ramp up/down times of the original horns/rotors programmed into them. You can set a top speed for fast, and a minimum speed for slow. Some people with foam rotors notice that the speed change is different than the wooden ones, simply because they are different weights. You could use an inexpensive Ebay foam rotor assembly, and replace it's 110VAC motor with a DC motor, and have it programmed to spin up/down like a wooden rotor.

There were some three-channel Leslies as well (Wurlitzer 212 and others).

I use horn/rotor with 800hz crossover with guitar/gamba and actually like it quite a bit .

The horn may be a bit more subtle (though if you fuzz up, you get more high frequency content which gets more dramatic) which I find to be a good thing...less listener fatigue.

The net effect is sort of like using a hi-band flanger (or effects that are set up for bass where the fundamental is lo-passed uneffected) in term of the horn, your fundamental is subject to the rotor and timbre and presence gets sort of a "shimmer" from the horn as opposed to a full on warble -- sort of a chorus feel as opposed to a vibrato feel (I'm using the terms aesthetically, not technically)

dont get me wrong..you jack the high speed and it's pretty warbly (but with the fundamental) with stuff like the motion sound 145 that has a lot of indpenendent adjustment over the horn and rotor you can really dial in some sweet spots and it's kind of nice to think in terms of "fundamental" and "overtones" (just to streamline the thinking during tuning)