One of the things that owners of long chains of analog effects pedals often say about multiFX like the Digitech RPs is that the multiFX boxes lack real time control–the kind of control you get by twisting dials on the pedals in a chain. The fact is that all of the Digitech RPs give you control over at least a couple of FX parameters in real-time, and some give you control over ANY parameter in real time.
We’ll start with the basics. Every RP from the 150 up gives you real time control over master (device-level) volume and FX level. The rightmost knob controls master volume, and the next one to the left is the FX level. Not very fancy, but those are probably the two controls you want the most at any given point in time. “FX Level” controls ALL the FX in your RP’s FX chain, including whatever modulation effects you have in play, as well as delay and reverb. It’s powerful–you can control how fast and how much you bring your FX chain in with one hand.
The RP350/355 add knobs for Amp Level and Amp Gain, which are critically important for shaping the tone on a particular patch while you’re playing. Gain in particular has a big effect on how distorted the sound is, and that’s pretty important stuff.
Finally, the RP250/255/350/355 have that lovely footpedal, which you can assign to anything you like–effect level, distortion mix, delay length–you name it. That means that in an RP350 or 355, you can control up to five elements of your sound with dials or footpedal, and up to four with a 250/255. Not too shabby.
A chain of five analog footpedals might give you anywhere from 5-15 knobs or dials to turn, anytime you like. The RPs don’t quite get all the way there, but they do let you change your mind about a lot of important stuff while you’re playing. They let you make complex, instantaneous changes that would be physically impossible to execute on multiple devices at the same time. And that’s all good.