Boss RT-20 rotary simulator reviewed
I was able to play one of the new Boss RT-20 rotary simulators today. This is one of the "double-wide" dual-footswitch units. It's laden with knobs, lots of knobs: a mode selector, separate wet and dry level controls, an accelleration control, separate horn and rotor speed controls, a horn/rotor balance control and a drive control.
The footswitch functions are simple: one engages the effect, the other switches between fast and slow speeds. If you press both footswitches at once the simulator applies a "brake" that stops horn and rotor. I'm not sure, but it seemed that releasing the brake always spun up to the fast speed... maybe I just wasn't paying close enough attention.
Three of the modes emulate a Leslie 122. The first two modes differ only in mic position, IIRC. Frankly, I couldn't hear any real difference between them. The third mode is supposed to emulate a Marshall amp driving the Leslie - this should make John Lord fans very happy. The fourth mode is a not-very-good Univibe emulation.
So, does it sound like a real Leslie? Short answer: yes, kind of. I mean, it does sound a lot more like a Leslie than the usual "make do" substitution of a chorus or vibe unit. The key elements are all there: independent horn and rotor sounds, independent accelleration and decelleration to a new speed, and the distinctive grind of the Leslie power amp.
The biggest flaw is that the pedal kills off the "presence" frequencies and makes the guitar sound dull, with or without the effect engaged. If it was simply dull in bypass, you could almost justify adding a looper switch box to turn it into a true-bypass pedal. At that point, though, you're out the cost of a DLS RotoSIM. A secondary flaw is that the RT-20, like every Boss pedal I've heard, also rolls off the low end. And having poor response in those high frequencies really makes the horn emulation sound second-rate.
There's a pretty narrow range of settings where the RT-20 sounds like a real Leslie. Those settings, oddly, are not with all the controls at their midpoint. And there are a lot of settings that are little more than bizzarre mutations of the Leslie sound.
All in all, I'd recommend spending the extra $75 on the DLS RotoSIM. The Boss RT-20 sounds a lot like a Leslie, but the DLS does a really compelling emulation.