I’ve always tended to focus on analogue guitar effects, as these offer much more subtlety in the circuit design than their digital counterparts. Looking at some of the DSP algorithms commonly available, they really don’t do a great job of simulating analogue distortion. That’s perhaps unsurprising, as distortion pedals are very non-linear and, thus, difficult to simulate with any real accuracy. Digital distortion typically involves simulated hard clipping combined with filtering, but this is a fairly naive approach.
There are, though, times when digital effects excel, and are often the only way to create specific sounds – these are all your delay and modulation effects that typically sit in your effects loop after the preamp, or at the very end of your effects chain if your amp doesn’t have a loop. Multi-effects processors that are ideal for this purpose have been around for many years, but they all tend to be limited to doing one thing at a time. Yes, you can chain multiple units together, but this is both expensive and cumbersome to manage. Furthermore, temporal effects (particularly delays) may need to be related to tempo, which requires you to make simultaneous changes to multiple effects when adjusting tempo.
A perfect example of the value of a simpler approach is The Edge’s use of multiple delays and many other effects. To play “Where the streets have no name”, you need a dotted 8th note main delay combined with a parallel delay of around 510mS, followed by some slapback delay. There is no single delay pedal that can do this, even though the delay is perhaps the simplest possible effect in terms of processing power needed.
Having spent many years programming embedded microcontrollers, I have long wished that there was an “arduino-like” device that you could use for audio signal processing, and now my wish has come true in the shape of the Daisy Seed by Electrosmith. It offers a pair of high-quality audio codecs in tandem with an ARM M7 processor and an easy programming framework. It has ample I/O for controls, and I now have this on a board with 6 pots and an expression pedal, 2 shaft encoders with switches, 4 momentary switches, 2 LEDs, and an LCD display. This could even be expanded further, as 4 I/O pins are currently connected for detecting input and output jack insertion (which isn’t necessarily useful).
Using the standard libraries and VS Code, it’s very easy to set up the software for this platform as a guitar pedal, and this then unlocks the potential to greatly simplify that effects loop. Creating the build block effects is easy, but the fun starts when you add compound effects that apply processing in series or parallel. While this would be insanely complicated to configure dynamically using knobs and switches, it’s trivially easy at compile time. Add in some preset functionality and you’ve got all the processing you need in a format that is easy to use live.
My effects loop used to have an EQ pedal, two delays, a flanger, a multi-function (one at a time) modulation pedal (Chorus, Phaser, Flanger, Tremolo, Vibe, etc.) and a reverb. That’s now all been replaced by a single box that can do far more than the individual effects could ever manage. I’ll obviously do a fuller write-up in due course.