Square Earth Theory – audio slicer pedal

Posted: November 23, 2012 in FX, Square Earth Theory
Tags: , , , , , , , , , , , , ,

Anyone who has followed the progress of any of my pedals within the last year may remember this post I made way back in January of 2012. Or you may not, hell I hardly remember writing it! But anyway, in that post I started harping on about this idea for an auto stutter/killswitch type device that is based on two 555 timers, and allows you to set 2 independent frequencies, decide how to combine them to make one pulse and use that to stutter your guitars signal. The last week or si I’ve been working on the circuit and it is nearly at a point where I’m going to start making a few, just as soon as I can iron out a few small issues (thanks to the guys at DIY Stompboxes). It is not actually based on 555 timers but 2 4047 oscillators operating in astable mode, which cause either a 4066 or 4053 to switch the signal, creating the stutter. I won’t go into the components I’m using now as it may well change, and when I have finalised the circuit I will post it up with an explanation anyway.
The pedal will feature 2 pots – rate a and rate b (can’t tell you the range of the frequency yet as even that isn’t fully decided!) and 3 toggle switches. A/ab allows you to select either just oscillation a or oscillation a and b. And/or controls how frequencies a and b combined – either both on or either on, and invert which flips the output of a/ab. A, b and the combined logic will all have their own LED. The pedal will be momentary, so your signal is unaffected until you hit the stomp at which point stuttering begins and continues, until you release the switch. By combining the 2 different oscillators you can create some really cool patterns, and it actually has a very mathematical feel especially when using ab and using the and setting. That probably makes little sense, here’s an idea of what the pedal may look like, I’ll get a video up soon once I iron out the few small problems with the design.

Imagine it as a square wave tremolo with the depth up full and you will get some kind of idea as to how it sounds in ‘a’ mode, ‘b’ mode sounds much more pattern based, although the patterns are only very simple with the 2 oscillators. I wanted to add a blendable fx loop so the pedal could stutter between dry and wet, but that was way too big for the 1590B version, maybe if it is a cool design I’ll build a 1590BB version with more oscillators, a blend control and a fx loop!


  1. Ryan says:

    That sounds super cool. I’d probably get in on one of those proto’s!

  2. Schpudd says:

    Wow… I’m in Ben, if you do a few of these I’d definitely pay to take one off your hands.

  3. 0xdfx says:

    Cheers guys! I’ll keep you updated if I can get it finished. Basically it all works well, but I get a slight popping when the signal is returned that I am struggling to get rid of. I know it is possible to do well as other people have done it, but I’m struggling to work out what is going on. I’m thinking get rid of all the toggles and replace the with a 4 way rotary switch to select a/a and b/a or b/a xor b and also a depth control so you can go from a full cut to no cut at all. I’m not sure how useful a depth control would be though, when I have played with it I have it either very subtle – almost like a bit of light trem, or full stuttering. The invert feature probably isn’t as useful as I originaly thought, so it will end up going. The other problem is all the cmos chips take up a fair bit of room, so squeezing it into a 1590B (MXR sized) enclosure could be pretty tough, and I don’t want to go bigger if I can help it! I’ll try and do a vid over the weekend of what I have got so far so so you can see it in action.

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