HawkeyeKane
2294 posts
Feb 01, 2014
11:45 AM
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So I have the itch to build a kind of passive rotary speaker cab. I'm not gonna be using it with an organ. Primarily to experiment with Barbeque Bob's suggestion a while back, I'd use it with my harp amps and maybe a little guitar. That being said, I've pretty much decided that I'm not gonna go the Leslie route with the crossover and tweeter horn. Just woofer driver and drum. I came up with my own design and I wanna run it by the amp gurus here on MBH for input. It utilizes a pair of woofers and drums in a horizontal configuration with the drums on a single shaft with the motor. Here's a rough draft sketch...
The chambers would have angled backs to direct the sound forward. I'm basing a lot of my limited knowledge on Leslies from basic info on Wikipedia. In my head, it seems like my horizontal design would work. But every other rotary speaker design I've seen or read about has been a vertical setup with independent motors. Like in this animation...
So....does anyone know of any reason why the horizontal single shaft design would prove ineffective? Motor noise maybe? Would the drum angles need to be concurrent, or should they be inverted with each other? Would coaxial drivers be a good idea? I'd really like some feedback on this.
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Hawkeye Kane
Last Edited by HawkeyeKane on Feb 01, 2014 11:53 AM
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tmf714
2395 posts
Feb 01, 2014
4:49 PM
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A keyboard player I know just ordered a new Leslie speaker with a 15" speaker and horn on top. Its digital,with variable speed much more adjustable than the old Leslies.
I will be playing through it,hopefully with guitar and bass-video to follow-
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Chinn
108 posts
Feb 01, 2014
5:09 PM
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The keyboard player at the Rum Boogie on Beale uses a setup much like the one in the animation (I think).
One thing that would be interesting to know is if the low versus high pitch seconds would need a different rotational speed to get the effect right. It might also be nice to have the two on rheostats so you could vary the speed for best effect.
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Greg Heumann
2578 posts
Feb 01, 2014
5:14 PM
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Looks like fun.
I think you should reconsider orientation, though. Leslie's throw the sound left and right Your would throw it up and down. But there is typically a lot less space in a venue between ceiling and floor than there is between the walls....
P.S. - Cool animated drawings. How did you do those?
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/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
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Last Edited by Greg Heumann on Feb 01, 2014 5:16 PM
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tmf714
2397 posts
Feb 01, 2014
6:08 PM
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Here is the one I will be playing through-300 watt amp with a 15" speaker and horn-
http://hammondorganco.com/products/leslie/3300-2/
Last Edited by tmf714 on Feb 01, 2014 6:08 PM
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Barley Nectar
268 posts
Feb 01, 2014
6:23 PM
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Tim, first off have you seen these? http://www.ebay.com/itm/Vintage-Leslie-Tremolo-Rotating-Organ-Speaker-Model-10T-2S4-/310669833669?pt=LH_DefaultDomain_0&hash=item48555d75c5
I just gave one away to a buddy. These are mounted in the organ verticly, not as shown. Two speed units have two motors on a common shaft. They are light weight and fragile, well balanced and quiet.
Why two drums? One will work just fine. Also the drums, if two are used, should have both openings faceing the same direction. In phase. Otherwise you will get no effect because as one drum "closes" the other will be "opening" and it will be as just a plane speaker. Also note the belt driven rotor. This facilates drive speed ratio. In other words, finding the proper motor for variable speed, direct drive as you show in your diagram, will be difficult and costly.
These are installed in organs with the motor shaft parallel with the floor. The rotor is dense styrophome and typicly use an 8" speaker. I have experimented with these buy simply powering up one mtr or the other with a SPDT sw. Fast/slow. Drive the speaker with the extention speaker jack from your amp. I was not really thrilled with the results. I found myself keeping time with the rotor. I did not try one in a live setting.
If you are really set on this, it may be cheeper and simple to pick one up on Ebay. Plentyfull and cheep. Would be easy to build a box to house it. I have already considered this years ago. Good luck...BN
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HawkeyeKane
2295 posts
Feb 01, 2014
6:50 PM
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Greg, I didn't make the animated one. That I just imported from the Leslie speaker Wikipedia page for reference. The one of my design was a cut & paste edit of another diagram they have on the same page.
In terms of the directionality....youre right. I didn't think about the lateral scatter. But I'd be willing to bet that for harp purposes, going vertical with it would still work, especially with correct mic placement or angled panels. If I stood it upright, wouldn't the woofer on bottom have problems pumping upward? Seems like it would unless I used a speaker that's tamed to being in a closed back cabinet...
Goose, no I hadn't seen one of those. My band's guitarist told me I should look into one of those Motion Sound R3-147 rackmount units. I'm not thrilled with that idea though. I'm really out to build something of my own design. Why two drums? Why not? I'm experimenting and implementing at the same time to see what I can do with it.
Going with what chinn mentioned, I want to put the motor on a rheostat control that's mounted to an expression pedal so there are more amplitude options than just the good ole Leslie fast/slow. I'm thinking drill press motor since a lot of them have the brake circuitry already built in, and I could get a rheostat with something like 8 speeds fairly easily. The bigger concern I have with it is the EM signature that comes with rheostats, but I'll look into shielding when I cross that bridge.
Which brings me to ask about one other thing, and that's speaker selection. I had a couple of old busted JBL EON's that had potential donor drivers, but after reading impedance on them, I've decided against them. I'm toying with the idea of a pair of coaxial speakers since they inherently possess a full range. And Goose, it's funny you should mention that tremolo rotary using an 8" speaker because a couple of the coaxials I was looking at are 35W 8's. Only drawback is that I'd lose most chance of speaker breakup. What do you guys think on that?
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Hawkeye Kane
Last Edited by HawkeyeKane on Feb 01, 2014 6:56 PM
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HawkeyeKane
2299 posts
Feb 03, 2014
8:02 AM
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Goose, I was not offended by your comment FWIW...
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Hawkeye Kane
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HarpNinja
3737 posts
Feb 05, 2014
12:49 PM
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Have you thought about a pedal instead? Several work great for harp and even have stereo outs. It would be easier to load in, etc.
I can post an example, probably tonight. I cut my finger pretty bad, which required stitches and made typing/playing/customizing impossible, and then promptly had stomach flu, but I can finally get around to this post, lol.
I use a Tech 21 Rotochoir ($125 used), which has a wide range of rotary sounds, but am familar with several pedals.
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Mike
My Website
My Harmonica Effects Blog
Last Edited by HarpNinja on Feb 05, 2014 12:50 PM
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HawkeyeKane
2311 posts
Feb 05, 2014
12:59 PM
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Mike, yeah, I've considered it, and I may very well get one eventually. Right now, the tremolo on my Zoo gets me some nice ethereal vibes. I'm looking to do this more just to say I did it. Hands on approach.
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Hawkeye Kane
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dougharps
543 posts
Feb 05, 2014
1:24 PM
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A friend of mine is in a band, and uses two big Leslie rotary speakers for his harp playing. They weigh a ton and take up lots of floor space. They sound good and he uses them to good effect. During the course of an evening 5 or 6 songs AT MOST using rotary is about all that would be appropriate.
It is just an effect to mix up your sound with harp.
I would suggest either building a small unit like the Little Lanilei Rotary Wave Speaker, or just use a pedal as suggested by Mike. Too much loading and lifting in and out, too much floor space, too much room in the van for too little use.
Now if you have a Hammond B3 Organ that you will play all night, that's different!
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Doug S.
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HawkeyeKane
2312 posts
Feb 05, 2014
1:46 PM
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Well, truthfully, I wouldn't really be using this thing on a regular gigging basis. For that, I'd definitely go with a pedal or maybe a rack unit. Maybe take it out to gigs once or twice as a show piece. I wouldn't want to lug the thing around all the time. As I said, kinda just doing this for fun, for the experience, and maybe to let my band's guitarist try it out with his rig as well. He's a keyboard player too so maybe he'll wanna try it with his Korg.
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Hawkeye Kane
Last Edited by HawkeyeKane on Feb 05, 2014 1:48 PM
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STME58
640 posts
Feb 05, 2014
5:30 PM
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I can't help with the Amp electronics or much with the acoustics, but if you go ahead with this I could give you some tips on DC motor control. I don't know if other Leslie type systems use close loop control to keep rotations constant but it would be a good idea. It might also be interesting to vary the speed with the pitch. A bit trickier but definitely doable. If I were trying this on the cheap I would drive it with motor driver out of a scanner, because they are ubiquitous and I am familiar with them.
PS:I have got my scanner to play scales but not tunes yet.
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HarpNinja
3738 posts
Feb 05, 2014
6:31 PM
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Mike
My Website
My Harmonica Effects Blog
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