The magic is in having a little overdrive tubes, preferably and the all-important Leslie speaker. The internal rotor sound is very similar to a mic'd leslie. A Leslie can be modded for fast, slow and brake all footswitchable. The next big challenge for the Ventilator was in a live situation. Definiately keeping it in my set up.
It is built with guitarists as well as organists in mind, and would certainly stand up to the firmest of size 10s stomping away on it. It's not too big, and works with standard power adapters. Both are rotary-speaker simulators but they include additional features that make them neither Uni-Vibe clones nor No-Frills pedals. For istance, all those great spongey-sounding Rhodes tracks from the late 70's and early 80's see Steely Dan for many examples were often just a standard Phase 90 on the output of the piano. I'm not the most othrodox dude to say the least.
The RotoSim, very much like the rest of the Leslie pedals reviewed here, boasts of a large and broad stompbox that has a vintage feel to it. My keyboard player from my old band plays a Hammond Organ through his leslie and he always said he likes the sound of the Rotosphere. Combine it with a swirly modulation pedal for some truly fat, lush fake organ tones. The hands down winner for me, as a standalone unit, is the Ventilator. The last Leslie simulator pedal I owned before my current one was a Line 6 Roto Machine pedal which never really satisfied. Not to mention amazing Wurlitzer and Fender Rhodes electric piano sounds and a fabulous clavinet sound. Initially created for the Hammond organ in the late 1930s, the shimmering modulation known as the Leslie effect became the tone du jour for guitarists in the late 1960s.
Today, however, convincing rotary speaker emulations are offered in stompbox format by a number of manufacturers. It reminds me more of a Univibe than a leslie, when playing organ. The first of the five recessed controls on the top adjusts the overall speed of the virtual motors, then, moving from left to right, we have controls for acceleration, balance, drive and distance. It can be found on pedalboards of people like Noel Gallagher Oasis , Franz Ferdinand and others. Again the designer has paid close attention to detail here in precisely measuring the outputs of the Leslie 122 speaker, and setting all these controls to the 12 o'clock position closely mimics the characteristics of the original speaker. It certainly surpasses many 'real' tube overdrive circuits which, although containing a real tube, run off too low a voltage to offer anything other than visual appeal. We selected only those brands that accurately replicated the core effect of the rotating Leslie speaker-amplifier combo.
For guitar, I did not really like the overdrive sound that came with the effect. All the main controls are recessed into the unit, and the footswitches are of extremely sturdy construction. It takes the 3 dimensional sound and makes it 2 dimensioned. I am sure there will be no problems, but if there is, my moderation team will take action. I have also owned and used: Rotosphere doesn't nail a Leslie sound, but sounds good nonetheless Motion Sound Pro145 Poor tone.
In contrast, the Ventilator seemed a little more utilitarian in its sound, but I have to say that the effect is certainly as close as anything else I've ever heard, and is considerably better than many lesser wannabe Leslie models I've owned. It's always sounded pretty legit to me. The Lex pedal is probably one of their better ones though, and is better matched to guitar than it is to keyboards. Leslie Emulators go further than the previous entries, giving you control over slow and fast speeds, a natural-sounding ramp up and down as you change between them, stereo outputs and other niceties. The first thing I noticed on getting the Ventilator out of the box is its construction. I'll take my 122 over any of these, but it is hard to travel with that big box! I have recently lost my mind and paid for a Leslie 760 will be here in about a week.
I tried to do a search on that topic but came up empty. If you like or not, it's another point but don't say that it's better for guitar. Though his early cabinet had one speed—Tremolo fast —he later created a slower speed, called Chorale, so that the sound was always in motion. One of my major complaints with the Dynacord is that it changed to tone of my original samples way too much. The A100 has B3 guts witha few minor changes. It's a very easy sound to get from just about any synth. So that solved my longing for Leslie-organ.
For that reason, I have less interest in buying an actual Leslie speaker, and was thinking along the lines of the Ventilator for keyboard duties and Fulltone Uni-Vibe for guitar duties. And maybe a midi input so some parameters could be controlled manually. All my bandmates commented after the gig on how impressive the sound was. For keyboard players looking for the perfect Leslie sound, the is the best choice. It does a great job at sounding like a Leslie, and You Tube is. I had a chance to try a Sidewinder used recently on electric guitar Motion Sound product and ended up concluding that I'd just as soon use a Uni-Vibe for that chore.