for those of you not following the leslie thread. NEW!!!

[Ansil]

this is something i just did a while back for shits and giggles. and to agravate my room mate. i have actually not heard a leslie cabinet in person. so i dont' claim that it sounds like it i have in fact three peoples opinions here on it.


1. it sounds amazingly like a leslie.

2. it sounds nothing like a leslie but very interesting indeed

3. it has a unique sound to it that does in some ways mimic a leslie.



my personal opinion.. it adds a cool effect for movies and stuff. as well as guitar sounds.

the way i went about this is like this. the positive and negative signal are applied to the red and green terminals respectively. the two motors are runn off seperate controls


and they spin opposite each other.


http://www.geocities.com/austenfantanio//rotocabtypethang.htm


updated. i added an inside view of the box i am building it into.
_________________

[petemoore]

It's just enough to show you know what's up with this, however once again I don't follow exactly...this is a movable obsruction between a speaker and a mic [like a fan?]...Baffling...!!!

[Ansil]

It's just enough to show you know what's up with this, however once again I don't follow exactly...this is a movable obsruction between a speaker and a mic [like a fan?]...Baffling...!!!

moving speaker and baffle

[David]

Ansil, I salute you!  Here I sit and ruminate and ask stupid questions.  You must have been sitting in front of your computer laughing and thinking what a fool I was because I was trying to map ground you had already covered!  You've already done 90+ % of what I've been thinking of!  I'm really embarrassed.

Would you allow a mere piker to ask you a few questions?  Like, for example, what kind of motor did you use, and how did you accomplish the speed change function?

[mikeb]

It isn't possible to get something that sounds reasonably like a leslie without also constructing something of similar dimensions. Consider the radius of the rotating horn (in 122, 147 type cabs); the greater the radius from the centre of the rotating object to the 'mouth' of the horn, the greater the amplitude and frequency modulation. If you listen to the samples of the device linked to on the other thread, you can hear that the depth of the 'chop' just isn't there; it does make for a pleasing sound, but it doesn't make for a good leslie emulation. Similarly, having something that 'chops' the sound in front of a speaker will provide the amplitude modulation, but not the frequency modulation. This is why the Motion Sound product is cool, because it produces something that is similar to the real deal in terms of physical dimensions, but at the same time is more portable and manageable.

All of this doesn't consider the frequencies fed through the rotating bass arrangement, but the same principal applies.

MikeB

[bwanasonic]

My guess is this sounds more like Fender's *Vibro* thingy with the rotating baffle in front of the speaker. SRV used it to good effect. I'm not sure what the point of spinning the speaker on it's center axix is? I would think a simplified version with a static speaker would sound pretty similar. No? Post some clips...

Kerry M

[petemoore]

Seems like the air would be thrown into eddy's and accellerated and deaccellerated as the blades moved through and occupied space / left space open...the thicker the fan blade the more the air would have to accellerate as the blades volume took up space creating a doppler effect.

[Mark Hammer]

Is there a child alive who has NOT been mesmerized by what happens to their voice when they park themselves in front of a fan and talk?

The design is thoroughly capable of producing such doppler effects.  Does it produce those effects normally classified as "Leslie"?  Probably not, simply because of the physical dimension issues that MikeB raises.  With a much longer radius, a Leslie's horn does not have to move terribly fast (in terms of RPM) to yield doppler effects.  At 60rpm, a half second will have resulted in the rotor having moved a fair distance away at a fast clip (in terms of inches/cm per second) even though it has only completed half a rotation.   If you had a motor speed control so you could slow down your typical home air fan to 60rpm, and parked your face in front of it and spoke, you woud not likely get the pleasing watery throb of a slow-speed Leslie because the fan blades would not displace the sound wave enough of a distance in the same half-second.

Bottom line.  I wouldn't be surprised if you canget some nifty bubbly sounds, Ansil, and that is musically valid, but the slower modulation may be much much harder to nail.

Size matters.

[Ansil]

i aree with you mark, i also forgot to mention a couple of things. i will try to clear up a few of them now.

1.  when i did this i originaly found it to be too trebly.  so i painted the speaker cone with elmers glue and water in a 1:1 ratio.

doing this seemed to help give it less highs and keep the bass from farting out the speaker as much.

also i reapplied the same glue mixture in different sections somewhat mimicing the baffle.

2. since they spin in opposite directions it brought a whole new dimesnion to the sound.  i dont' know why i can only speculate that since they have similar baffles. moving them together would essentialy make it possible to line up the baffle and the speaker so since they are reversed it is almost never possible to get the baffles and the painted on glue to line up in a synchronized motion.  

3. the speaker is a aprox~ 4" 8 ohm speaker that i tried it with.

4. the motor was an old canabilized one that i found in the scrap box and one came from a cordless shaver.



5."(bwanasonic) Post some clips"... >>> would love to, i will finish the one i am working on now, and in about a week would someone email me a guitar..  :oops:  i dont' currently have one, most of my clips are done somewhere esle or i dig up older ones that i have on CD from my studio music.

[Marcus Dahl]

Great idea. It made me think that maybe it could be done on an even smaller scale and fitted into a 1590C box using lavilier mics and a one or two inch speaker. That way you could turn it into a pedal. I'll have to work on that. Hummmm  :idea:

[David]

Marcus, were you serious, or was that tongue-in-cheek?

[Nasse]

If you make the Hammond case watertight, fill it with some fluid that slows the speed of sound so that Hammond box volume looks like say a small club, youre done it. But I doubt the mic can survive it, you may need hard-to-find special transducers. Maybe that stuff used in lava lamps may work, it is fire resistant (sparks from motor brush!)

But another drawback may be when you kick the stompswitch and the fluid splashes around the case, but it could add interesting soundeffects.

I think my idea abot rotating drum around microphone is better

[Marcus Dahl]

Marcus, were you serious, or was that tongue-in-cheek?

Yes I was serious.  :?
The box may have to be bigger than a 1590C, but I don't see why it wouldn't work. It may sound a funny and nassel like. Although you may be able to get some cool tones out of it. you'd need to probablly use a LM386 type amp circuit to push the speaker, and you can get electric motors small enough that you could attach your speaker to with a speed adjust. I'd say 2 9volts could do the job. I'm going to work that up.

[bobbletrox]

A mini leslie inside a stompbox would be amazing!  It'd be a great little lo-fi effect I reckon.  You could even have a sperate enclosure for the speaker and connect it with RCAs to the stompbox containing the footswitch and electronics.

Speaking of DIY leslies, has anyone seen Jack White's Triple Tremolo?

[bobbletrox]

and they spin opposite each other.

Excuse me for being dim, but why does the speaker have to be spinning if the baffle is also spinning?

[Paul Perry (Frostwave)]

why does the speaker have to be spinning if the baffle is also spinning?

The rotating speakers (which may in fact be rotating speaker HORNS, which is a hell of a lot easier!) is a source of the doppler effect.
The baffle might be more like a tremolo (that is, a LFO volume control).
plus, it might act as a varying filter as well.
One of my happier memories from university days was when a band was playing at lunchtime with a Leslie.. a couple of physics dept. academic heavies were waling past on their way to the faculty club & started arguing about what they were hearing.. they were still at it some considerable time later

[bwanasonic]

The rotating speakers (which may in fact be rotating speaker HORNS, which is a hell of a lot easier!) is a source of the doppler effect.
)

But from what I can tell, in this case the speaker is spinning on it's center axis. This would not create a doppler effect.

Kerry M

[Ansil]

If you make the Hammond case watertight, fill it with some fluid that slows the speed of sound so that Hammond box volume looks like say a small club, youre done it. But I doubt the mic can survive it, you may need hard-to-find special transducers. Maybe that stuff used in lava lamps may work, it is fire resistant (sparks from motor brush!)

But another drawback may be when you kick the stompswitch and the fluid splashes around the case, but it could add interesting soundeffects.

I think my idea abot rotating drum around microphone is better

similar to my waterverb

[Ansil]

i dont' know why it makes a difference but it does on mine.

[Paul Perry (Frostwave)]

But from what I can tell, in this case the speaker is spinning on it's center axis. This would not create a doppler effect.
Kerry M

I don't think any of these systems have the actual SPEAKER rotating, because you would need sliprings to feed the signal to them & get hellish noise. In a traditional Leslie, you have horns (driven by a stationary speaker) rotating, and an angled baffle rotating above a fixed low feeq speaker.
A doppler effect can only be created (excluding electronic means) by varying the distance from source to ear. In the case of the horns, as they move around, the apparent (and actual) path length changes. In the case of the baffled low freq speaker, i doubt that there is much doppler happening... but, if someone could put a mic in front of a leslie & run a sine wave thru it at various freq, and compare the before & after on a twin beam scope, I'd be much obliged!