Leslie simulator

[marcos_s_p]

Hi guys,

Does anyone of you guys know a good DIY for a leslie simulator? I only know the wesley...but it's not quite it.

I came across this one, which isn´t exactly but I thought it sounded quite great. Does anyone has a similar project as this?

https://youtu.be/mqPdCXIX5ps

https://youtu.be/f2xW5VQzzjc

Thanks anyway!

Cheers!

[midwayfair]

The videos are just univibes or something similar. Madbean has a printed circuit board or there are a couple etch-your-own.

The Whirl mode on Runoff Groove's Tri-Vibe is okay at it.

Chorus pedals can do faster Leslie imitations, as can some other simple pedals with similar sounding effects. It's the slow stuff that's harder.

Actually emulating a Leslie is extremely complicated and is likely to be much better accomplished digitally.

[elseif]

In the 90s I captured the impulse responses of both the drum and rotor of a 122 Leslie speaker, measured at rotational increments of pi/16. It took me until 2018 to do anything with them (when I retired as a DSP engineer).  I did a simulation in Octave that showed promise.  I also built one using a TI L138/C6748 LCDK (low-cost development kit).

I started doing a schematic and layout - then I bought a Ventilator and dropped the project.  The simulation and the Ventilator were similar in sound but the Vent was much further along in development of the algorithm, usability and its physical construction.  I wanted one to use, not to produce as a second career. Why build what you can buy?

The simulation of the Leslie was made possible by the success I had simulating an A-100 chorus/vibrato circuit.  I used a similar cross-fading technique, though the Leslie had to deal with rotor acceleration and deceleration.

A-100 Chorus/Vibrato Octave Simulation

Chords-n-Bass Leslie Speaker Octave Simulation

[Mark Hammer]

Ding, ding, ding, ding!!!!  You win the award for the person asking the question THIS year.  It gets asked at least once every year.

And yes, as Jon/midwayfair notes, it IS complex to emulate a rotating speaker.  There are several things that have to be incorporated:
- the comb-filtering that the Doppler effect produces
- the slight lowpass fltering and slight amplitude-modulation (tremolo) produced as the rotor points towards and away from the listener
- the discrepancy in each of these as rotors for horn and woofer move around separately
- the "griind" produced by the power amplifier driving the cab
- the spatial swirl created by spinning rotors
- the gradually acceleration/decelleration (ramping) produced by the interaction of rotor mechanism inertia and speed switching

Vibes, phasers, and eventually some flangers and chorus units were designed to mimic the first attribute.  Some phasers, like the Pearl PH-44, several '70s Roland phasers, and one that Keeley made for a little while, have ramp-up/ramp-down.  While you'd think that ramping and some limited comb-filtering would nail it, you'd be wrong.  It gets you closer, but not all the way there.  RG Keen has designed and posted a circuit on his GEOFEX site for yielding speed ramping,

There is also the Rotosphere, which is likely the most accurate fully-analog emulation of a Leslie, but it is far from a DIY-friendly project.

The grind, ramping, and comb-filtering can be mimicked in the analog domain, fairly easily.  The rest of it, not so much, or rather, not so easily.  Some of the digital effects chips that have multiple "programs" built in, have a rotary emulation.  I can't speak to how good it sounds, but certainly it would simplify things if you're game for it.

And, as I always do, I cannot emphasize enough that most rotary emulators/emulations really need to be heard in stereo to truly capture the effect, and impress.

[EBK]

Ding, ding, ding, ding!!!!  You win the award for the person asking the question THIS year.  It gets asked at least once every year.

Technically, Mark, the question you are referring to was asked over 2.5 years ago in this thread, not this year.   

[anotherjim]

Look for a Korg G4 Toneworks. Some still speak of it in awe for its rotary sim, and that was made long ago. Neo Vents are expensive, but rarely criticised.
However, unless you are well endowed financially, they are all way too expensive unless it's something that is an essential part of your main sound, as it would be for an organist.

[Mark Hammer]

Ding, ding, ding, ding!!!!  You win the award for the person asking the question THIS year.  It gets asked at least once every year.

Technically, Mark, the question you are referring to was asked over 2.5 years ago in this thread, not this year.   

Hah!!    Didn't even bother to look at the date.  The question gets asked with such regularity, I just figured that if the thread was that short (because it's usually much longer) that it was simply "this year's" entry.  My bad.

Look before you leap, Hammer!

[Yazoo]

I've built a Rotosphere and I'm pleased with the result. It is a big project though, as pointed out. I had to get the two boards fabricated for me and the cost did end up being quite high, so it probably is one you should only do if, like me, once you start, you completely lose all objectivity. Please tell me I'm not the only one. 

[garcho]

Look before you leap, Hammer!

I've relocated to Richmond, Virginia from Chicago about 5 years ago, and it's been fun dipping my toes into the South, albeit at a distance from here in urban Bohemia. I was BS'ing the guy from the internet company installing the units in my house, when he said in molasses-thick Virginian diction, "My daddy always told me, never trust the man who jumps off the back of the truck and starts working as soon as he shows up. Every job is worth thinking over."

I think something a lot of people forget about when it comes to emulating acoustic/mechanical stuff, this particularly, is that listening to recordings of Leslie rotating speakers and being in the room with one are two vastly different experiences. If you want to emulate the "effect" you hear on a recording of a Leslie from 1969 or whatever, you really don't have to worry about as much of the technical stuff and the complex modeling. If you want your guitar to sound like it's coming through a Leslie for the people at your gig to experience the acoustic effect, then just put your efforts into making an actual rotating speaker. Otherwise don't sweat the small stuff and it will sound close enough to recordings to achieve what you want electronically from a univibe or chorus or what have you.

[Kipper4]

The vomit comet is still on my backlog list. Sounds good to my ears.

[anotherjim]

I think the stereo field of a Leslie has to be incredibly difficult to simulate and probably just as difficult for most of us to judge how well it's been simulated. Our heads surely hold a mental recording from records heard in the past without our ever having been close to the real thing - and those recordings could either be...
Entirely Mono.
Stereo but only a mono mic/track for the Leslie.
Fully Stereo.

On top of all that, there are the lucky people who have been regularly close to the real deal and it's the real world sound they expect from a simulator.

[Mark Hammer]

Couldn't agree more.  I think you make an important point about what the listener/user's point of reference is.  For some folks, what they think of when it comes to Leslie-tone is the bubbly fast speed, which could be recorded in mono OR stereo, and not sound appreciably different, since the fast speed distributes the sound in a perceptibly "equal" way (i.e., generally too fast to hear any side-to-side differences).  What the listener notices there is a unique kind of modulation that is capturable by some kinds/brands/models of modulation pedals, but not always nailed by every single one, even when it has the speed capability.

Slow rotation, however, especially when there is upward or downward ramping involved, starts to demand a stereo listening environment, since the spectral and amplitude differences, as well as ear-to-ear delay, between sides, becomes more noticeable, and certainly more obviously mic'd, than fast rotation.

Swirl needs stereo.  Bubbly doesn't.

[vigilante397]

Why build what you can buy?

Because I don't build things to use them, I build them to build them. I pretty much don't even play the guitar