The Tech 21 RotoChoir is a rotary speaker simulation pedal, built to recreate, or at least approximate, the swirling larger-than-life sound of a rotary speaker in a stompbox. MusicRadar's reviewer Trevor Curwen found the emulation of a rotary speaker convincing, though he noted the overall sound is dependent on the two tone knobs1. It sits among other rotary simulators such as the Strymon Lex Rotary, the Neo Instruments Ventilator and the Boss RT-20 Rotary Ensemble, and is one of a broader family of speaker simulation pedals.
Controls and footswitches
The RotoChoir keeps its control layout simple. A Level knob adjusts the overall output level, and the two tone knobs shape the sound, which Curwen found central to how the pedal comes across1.
| Control | What it does |
|---|---|
| Level | Adjusts the overall output level1 |
| Two tone knobs | Shape the overall sound, which the reviewer found the emulation dependent on1 |
| Bi-amped switch | Selects between a traditional Leslie 122 style split between top and bottom rotors, or a full-range bottom rotor as in a Leslie 125 or a Vibratone1 |
| Fast/slow switch | Switches rotor speed1 |
Two footswitches on the floor offer familiar bypass and fast/slow functions, so speed changes can be made while playing1.
The bi-amped switch is the pedal's main take on how real rotary cabinets were fed. One position gives the sound of a traditional Leslie 122, with the signal split between the top and bottom rotors; the other gives a full-range bottom rotor, as heard in a Leslie 125 or a Vibratone1.
Speaker simulation character
Tech 21's speaker simulation setting is designed with inherently erratic and irregular peaks, valleys and notches, which the maker says give that familiar, unique raspy grind1.
"The RotoChoir's emulation of a rotary speaker is convincing, but the overall sound is dependent on the two tone knobs."
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Questions
Does the Tech 21 RotoChoir run on a battery?
Yes. According to MusicRadar's review, the RotoChoir can run from a 9V battery, or alternatively from a standard BOSS-style power adaptor, so it will fit into a typical pedalboard power setup as well as working on battery power.
Is the RotoChoir analog or digital?
It is neither purely one nor the other. MusicRadar's Trevor Curwen describes the RotoChoir as utilising a mix of analogue and digital technology to produce its rotary speaker simulation.
What does the bi-amped switch do on the RotoChoir?
The bi-amped switch changes how the simulated rotors are fed. One position gives the sound of a traditional Leslie 122, with the signal split between the top and bottom rotors. The other gives a full-range bottom rotor, as heard in a Leslie 125 or a Vibratone.
Does the RotoChoir have a fast and slow speed?
Yes. The pedal has a fast/slow switch, and its two footswitches offer familiar bypass and fast/slow functions, so you can switch rotor speeds from the floor as you would on a real rotary speaker.
Sources (1)
- Tech 21 RotoChoir review, MusicRadar, 2011-09-26
