We've wrestled, figuratively and literally, with using or emulating a certain electromechanical tremulant device which is housed in a heavy, fancy wood cabinet. I hesitate using the name because I don't want any patent lawyers coming after me. I have a couple of ideas for a micro version of said device. I believe I've done all the due diligence that was available, so now it's time to ask questions.
It seems to me that one could make a version of this well-loved effect by driving a speaker with a Little Gem or other low-power amplifier such as Javacody's 386 amp with EQ. One could then have the speaker firing into some kind of baffle (maybe a DC-powered computer fan?). I know that this baffle would have to rotate at 60 r.p.m. for the slow speed and 340 r.p.m. for the fast speed. I would think that speed of a DC motor could be set and/or varied by using pulse-width modulation or the "inductive load-rated zero-crossing relay" documented in a thread on the SSR. One would then mike this small device to get the swirl.
I'm guessing that what I'm suggesting here must be too simplistic an approach or someone much wiser than I would have done it by now. Messrs. Hammer, Keen, Orman, petemoore, and anyone else who has ever tried this:
Am I barking up the wrong tree? If so, why?
Is this worth taking further? Can someone tell me what the next step might be?
Not too sure I follow so...
Are you talking about running airborne sound [liike in front of a speaker] through a channel which can be alternately opened and closed using rotory doors? something like Beatles "blue Jay Way" effect that sounds like singing into a fan?
Tolerances with something like this would be paramount. Flat fan blades should take much of the air flowing sounds from the effect and make it easier to align the spinning blades through the slice of the chamber [Sounds like something from "Pit and the Pendulum".]
Another way would be to have a plate that has close tolerance to the chamber walls fit with bearings and spinning like a furnace vent tube valve.
Quote from: DavidWe've wrestled, figuratively and literally, with using or emulating a certain electromechanical tremulant device which is housed in a heavy, fancy wood cabinet. I hesitate using the name because I don't want any patent lawyers coming after me. I have a couple of ideas for a micro version of said device. I believe I've done all the due diligence that was available, so now it's time to ask questions.
It seems to me that one could make a version of this well-loved effect by driving a speaker with a Little Gem or other low-power amplifier such as Javacody's 386 amp with EQ. One could then have the speaker firing into some kind of baffle (maybe a DC-powered computer fan?). I know that this baffle would have to rotate at 60 r.p.m. for the slow speed and 340 r.p.m. for the fast speed. I would think that speed of a DC motor could be set and/or varied by using pulse-width modulation or the "inductive load-rated zero-crossing relay" documented in a thread on the SSR. One would then mike this small device to get the swirl.
I'm guessing that what I'm suggesting here must be too simplistic an approach or someone much wiser than I would have done it by now. Messrs. Hammer, Keen, Orman, petemoore, and anyone else who has ever tried this:
Am I barking up the wrong tree? If so, why?
Is this worth taking further? Can someone tell me what the next step might be?
i feel what you are saying i will draw up something tonight.
I suppose a rotating speaker gets a lot of its effect by changing the path length of the audio from speaker driver to listner. Now if you has a bunch of vacuum cleaner hoses of different length, and a rotating culinder with a holes in it so you could switch between various lengths, then maybe that would work. I can see having a small primary speaker, then a mic at the output & then putting that thru the main amp. The kind of technology you have in the talk box might be appropriate.
They do have portable leslie simulators that you can carry now. Motion sound, makes one I think.
The idea of a tiny one is cool though. You should make it.
Aron:
I know about the Motion Sound unit. It's too expensive. Actually, it's also too big. I'm envisioning something about the size of a Pignose.
I do want to take a crack at building this thing. I just have so much I want to build and so little time that I don't want to waste any of my precious bench time chasing down dead ends.
To continue:
I haven't heard anyone shoot my idea down. All right, on to the next step. This is where I have no experience or knowledge at all. As Dr. McCoy might have said, "Dang it, Jim! I'm a systems analyst, not an electrician!" Anyway, supposedly the "baffle" has to spin at 60 r.p.m.
for "slow", and about 340 r.p.m. for "fast". If I'm using a DC motor (I'm thinking I could do this with a low-voltage fan), can I just vary the speed with a resistance? Or do I need to get into using PWM or that zero-crossing relay thing?
Here's another question:
Is there an easy way to measure the r.p.m. of the motor? I never bargained on needing a tach to build effects!
And put a brake on it...you should be able to slow it down but it may be tricky to get a stable RPM that way.
Many fans have the three way speed selector...but they go probably from very fast to way too fast to so fast it might as well be still?
Voltage divider? OK...I'm shooting straws...
since I posted this:
http://www.diystompboxes.com/sboxforum/viewtopic.php?t=9610&postdays=0&postorder=asc&start=26
I've had the chance to see a real Leslie in action. I realised that while you can get pleasing effects by spraying your sound all around a room, the real magic in a Leslie comes from the Doppler effect. The amount of frequency shift is dependent on the linear velocity of the sound source with respect to the listener. The linear veocity of the end of the horn on a leslie is dependant on the rate it's spinning and the length of the horn. They have to be as big as they are to get the same depth of modualtion.
So in theory it won't work, but since when did theory and practice ever agree? Build it.
Quote from: Paul Perry (Frostwave)The kind of technology you have in the talk box might be appropriate.
Just last weekend I was swinging the hose of my talkbox above my head (much like I had seen the Doppler effect demonstrated in high school except they used a whistle into a hose). Pity there was no-one around to hear it and it doesn't work if you're in the middle of rotation.
Darren
Instead of a fan, the speaker could dump into a piece of PVC pipe that spins at the appropriate speed. There's the Doppler effect!
Quote... There's the Doppler effect!
The Doppler effect is duplicated exactly by a varying time delay as in a flanger or even some phasers set for "vibrato" by removing the dry signal from the output mix.
Leslies are more than that. There's a web page somewhere that addresses some of the subtleties of the effect.
A good leslie simulation is remarkably hard to do in a non-stereo, non-mechanical effects box. You have to simulate the varying frequency Doppler effect (easy), the varying amplitude as the horns/bass rotor face toward/away from the listener (simple, if harder to do well), the spatial effect of early and late reflections from walls and ceilings (hard to do without at least stereo and maybe some DSP). Leslies give a major workout to the human ear's psychoacoustic frequency sensing and localization mechanisms.
Leslies have been popular enough that if it was simple to emulate, there would be Leslie simulators everywhere.
The simplest way to do a Leslie simulator is - build some variation of a rotating speaker setup. That one should work well. I've seen some things that rotate speakers in a vertical plane instead of a horizontal one.
OK, R.G., I read the reference you mentioned. Hope my customer doesn't noticed that my delivery date just slipped. I see that a Les*&^ is more than just Doppler effect. Actually rotating a speaker or pair of speakers would involve some kind of arrangement of "points", probably some kind of vibration dampening, bearings, and now I'm rotating more weight, so I have to come up with a bigger motor.
That should make me quit, but dagnabit, I have a feeling there's a way to make this work -- at least for a guitar, which is all I want. And by the way, thanks for bringing me back to earth.
Any ideas about controlling DC motor speed and braking?
The way the Leslie-ish things I've seen do it is with a bass speaker mounted on the bottom of the cab, firing upwards into a styrofoam cylinder with a port cut from the bottom center curving up and to one side. The styro cylinder rotates, the speaker doesn't. One of them had what looked like a styrofoam cylinder that was cut at a slant across one end, and the slanted end pointed to the bass speaker. Same principle - the opening rotated, not the speaker.
I wonder if you couldn't get the same effect with a 5 or 6" speaker and a 6" pvc tee fitting set up to rotate.
The highs are done with two smaller horns mounted on a rotating disk or arm.
The low frequency and high frequency rotors are independent, driven (by belts in some units) by AC motors. The motors are set up so they are merely switched on and off. The ramp-up/ramp-down speed thing is done by the mechanical inertia that the motors have to pull - the motors are not variable speed, just highly loaded.
Quote from: R.G.I wonder if you couldn't get the same effect with a 5 or 6" speaker and a 6" pvc tee fitting set up to rotate.
That's exactly what I was thinking! Yee-hah! I'm on the right track!
Now, I understood your comment about braking -- the weight of the baffle contraption IS the brake. Logical. OK, so now I have to find a motor with the cojones to spin this PVC tee. Further, I have to have a way to spin this baby at "fast" and "slow". Would it work to use two high-wattage resistors to select the appropriate r.p.m., or am I still missing something? I don't expect this to be invented for me, I just need a little push over the rough spots.
By the way, I'm NOT thinking about using an AC motor. 12VDC or something similar is more what I had in mind.
If anyone's interested here are a few links:
http://theatreorgans.com/hammond/faq/mystery/mystery.html
http://www.dairiki.org/HammondWiki/Leslie
http://www.soundonsound.com/sos/jan01/articles/vintage.asp
this isn't acutally what you said to the detail 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.
there is a company that has already done this......
the size is a mere 8" x 8" x 12", weighing in at 7 lbs.
here is the link!
http://www.songworks.com/index1.htm
they also have one that is slightly larger too.
super cool company.
look to the left....it's called "rotary wave." they have a 6.5" version of
it. and an 8" i think.
If only I could afford that...
Doesn't seem to be much in that RotaryWave thing.. anyone seen inside? if it is just a spinning baffle (like the bottom half of a real leslie) then anyone could make one, pretty easy. Maybe from a fan with a carved chunk of polystyrene on it! and a speed control.
Instead, why don't we do this:
1. Crossover split the input signal, about 600hz like the real Leslie
2. Use a phaser (p90, p45, univibe, etc.) in vibrato mode for the frequency/Doppler shift and run the highs through this.
3. Use a tremolo circuit on the lows
4. Use just a hint of tremolo on the highs to fake the amplitude modulation in sync with the LFO for the highs
5. Mix all the stuff back together
For extra credit -
Make two, use one feeding one side of the room, one feeding the other through a different amp/speaker and at a slightly different frequency.
ok that sounds cool RG so we can't play with my idea. sniff sniff.. :wink:
The crossover frequency is 800Hz, and the gentleness of the roll-off means some frequencies are reproduced by both the treble horn and bass speaker.
MikeB
OK, R.G., I'll give that a try! Don't look for a fast build report, though. It'll take at least a couple of months before I have anything at all.
Ansil:
I still like the electromechanical idea; let's not let that get lost. How about you tell me how or if you handled the variable-speed issue. Also, are you spinning the speaker only, or the speaker and baffle together?
Quoteok that sounds cool RG so we can't play with my idea.
Of course we can play with your idea.
How's this: get some 4" PVC plumbing pipe, a big "T" fitting and two one-foot sections. Glue the one-footers into the cross of the T, and rig it so you spin the opening in the middle of the T over a 5" monitor speaker. If you like, stuff styrofoam into one of the one-foot ends to halve the effective rotation speed. Maybe glue styrofoam into a disk around the unit so it is not quite as likely to whack someone walking into it.
QuoteInstead, why don't we do this:
1. Crossover split the input signal, about 600hz like the real Leslie
2. Use a phaser (p90, p45, univibe, etc.) in vibrato mode for the frequency/Doppler shift and run the highs through this.
3. Use a tremolo circuit on the lows
4. Use just a hint of tremolo on the highs to fake the amplitude modulation in sync with the LFO for the highs
5. Mix all the stuff back together
Wouldn't you need some pitchshifting to happen as well? Like in a vibrato (with bbd's)?
Quote from: R.G.Quoteok that sounds cool RG so we can't play with my idea.
Of course we can play with your idea.
How's this: get some 4" PVC plumbing pipe, a big "T" fitting and two one-foot sections. Glue the one-footers into the cross of the T, and rig it so you spin the opening in the middle of the T over a 5" monitor speaker. If you like, stuff styrofoam into one of the one-foot ends to halve the effective rotation speed. Maybe glue styrofoam into a disk around the unit so it is not quite as likely to whack someone walking into it.
lol i was just kidding :wink:
Quote from: R.G.Instead, why don't we do this:
1. Crossover split the input signal, about 600hz like the real Leslie
2. Use a phaser (p90, p45, univibe, etc.) in vibrato mode for the frequency/Doppler shift and run the highs through this.
3. Use a tremolo circuit on the lows
4. Use just a hint of tremolo on the highs to fake the amplitude modulation in sync with the LFO for the highs
5. Mix all the stuff back together
What about this?
1. As indicated
2, 3, 4. A Zombie Chorus with Mark Hammer's "Badge" modification for the highs and another for the lows (tweaked for bass response). Drive them both from a single oscillator rigged to pulse at 60 for the slow speed or 340 for high speed.
5. As indicated
I think it would be cooler to use a separate LFO for each section, so you can control the speed independently like in a real leslie.
Arn:
I don't recall seeing a Leslie that had independent speed control for the bass and treble rotor mechanisms. I worked with a keyboard player that had the Leslie Combo Preamp unit. As I recall, it had fast and slow speed controls.
David, to be honest, I don't know.
But if you want to include a ramping mechanism for switching between slow and fast speeds, you do want to control them independently because I believe the acceleration of each rotor isn't the same.
Btw, I was browsing through some patents on this subject. There's some pretty interesting stuff to be found for the more knowledgeable people (not me):
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=4,000,676.WKU.&OS=PN/4,000,676&RS=PN/4,000,
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=4,428,270.WKU.&OS=PN/4,428,270&RS=PN/4,428,270
Since this popped up I could not resist to open my big mouth
Of course I could have posted this for Ansil´s thread about almost same things, but anyhow, I dont have a coin to throw...
I was testing that software rotary speaker emulator with fancy and plentiful controls of various parameters. I got some ideas, which are not tested or I am not sure about them, but ayhow...
I quess it may be useful to make crossover freq adjustable for guitar use. Original is fixed, but adjusting it in emulator made interesting chances in sound. If guitar signal is not so interesting as tonewheel magig sine waves this may help, but just an opinion after short listening with some organ tracks
R.G suggested making it two in stereo setup. I think I heard in my soft simulator that the mix is probaply feed to a (slow?) phaser at the end of chain, maybe that simulates the sound motion in the room. That may be the cost-effective solution, but maybe not as good.
Nasse, what software is it that you're using?
Oh, that was just something that come with Steinberg Cubase, a plug-in named Rotary. I think I have to fiddle with my files and folders, I cant make it work with my audio editor program, that has some meters like spectrum analyser and phase scope.
But I´m really novice with these
QuoteWhat about this?
1. As indicated
2, 3, 4. A Zombie Chorus with Mark Hammer's "Badge" modification for the highs and another for the lows (tweaked for bass response). Drive them both from a single oscillator rigged to pulse at 60 for the slow speed or 340 for high speed.
5. As indicated
Is there anybody who thought some more about this idea? I think it's kinda interesting. The H&K Rotosphere uses a similar kind of configuration.
Maybe a more simple version that uses a tremolo for the lows would work as wel. It might also be interesting to make a crossover network on a breadboard and use your typical chorus and/or tremolo pedal and a mixer to hear how it'll sound...
What would happen if I used a full range guitar speaker (just a normal speaker without the Leslie crossover network) with a Leslie bottom? Would it just be a tremolo sound or get that chorusey sound?