The Lowest-Fi Digital Delay

A little while ago, I built my own Lo-fi Arduino Guitar Pedal. I’m even using a similar enclosure – work tossed out a couple of thinwire->twisted pair converters that I snapped up. I think the only major deviation is that mine only has one output at present- I could add a second later, though.

I got to thinking last week that a digital delay would be an interesting idea – I had no notion that this would compete with anything in the quality department- a very short, crunchy delay – I just wanted to try it out.

So I wrote a little program and originally used an array of 512 values, and cycled through them, while recording point i, and playing point (i+1) (with edge checks and things like that, of course)

It turned out that 512 shorts of storage must have overflowed available program memory and caused general non-functionality. Changed the delay to 256 shorts. That at least got me up and running.

And it gave me about a second of delay time – kind of unexpected (that makes the sample rate, what, a few hundred Hertz?). It also doesn’t give a very accurate representation of the input. A test went something like this: snare (pause) krrrzzk.

audio: ArduinoDDL1.mp3

Once I commented out the #define DEBUG 1 line, it seems a lot happier 😉 There isn’t very much delay time, and it still gets really weird on occasion, but it does kind of do something to the input.

Here’s an example of it, with adjustments to the amount of delay and effect mix: ArduinoDDL2.mp3 – note that it gets loud and obnoxious in places.

Maybe better than the crappy plate reverb of a few weeks ago? Really, hotrodding my Realistic would be the best way to go for the all-DIY album. Probably not enough time for that, though – I’d really like to get it done soon.

If you’ve built a Lo-fi Arduino Guitar Pedal, get the code here: ArduinoDDL.zip. Knob A controls the delay time, and Knob B, when set to zero, should flush the audio buffer and blink the blue light while it’s doing it. Or it’ll just do weird stuff. YMMV – mine certainly does.

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