I use bypass loop pedals all the time in my pedalboard. I have two double loops made by Loooper which are just great–he does excellent and tidy work. If you don’t want to build your own stuff, I highly recommend getting one made by Loooper.
I wanted to build one of my own, and added a wrinkle I had seen before and wanted. On this box, Pedal 2 is the loop switch. Pedal 1 feeds some of the output of the loop back to the input of the loop. The big ugly knob controls how much output is fed back.
I’m not the first–or even the 100th–to make a pedal like this. I used a schematic from the excellent Beavis Audio site, to which I would link, but the dude who runs it let the domain expire. Today. This is an excellent resource for DIY stuff, and I’m going to donate to help keep the thing up. You can find similar schematics all over the Web, but this one was extremely clear and well-drawn.
This is a very simple circuit–all it does is route your guitar signal one way or another, not actually create any effect–but bypass loops are extremely useful. It’s also the first pedal I have built from scratch. I’ve fixed lots of things, and built the odd channel switch and whatnot, but not really tried building anything audio passes through from the get-go.
There are several reasons why this one worked out so well:
- I went PAINFULLY slowly, measuring, cutting, cleaning up, and continuity testing after every step. I don’t want to be this slow forever, so the more I learn with each build, the better. I don’t mind learning from mistakes, but avoiding them is even better.
- I built it in my lovely prototype box, which as you can see is an old Vox channel switching pedal. What you can’t see is that this box has about 10 holes drilled in it from various prototyping things I have done previously. Putting this in a box I ultimately didn’t want to use pretty much ensured the pedal would work perfectly.
- After I had drilled the hole for the LED, I decided to change the switch positions around. And that is why you can’t see the LED. It works, but it’s still inside the box. Very proud of that. Yep.
I planned to get the circuit working, and then move it into a nicer enclosure, but I have a fondness for good things that look bad, so it might end up staying where it is.
Here’s what I learned from this build, which might be useful to anyone else who is starting out building or repairing circuits like this:
- You will be much happier if you have lots of different colours of wire. Really. You won’t remember which bit of wire is which the moment you close the box, so if you have to troubleshoot a mess of say, white wire, you will hate life.
- Really get to know the circuit. Figure out how you want to do the build BEFORE you start melting any lead.
- Look for points where multiple bits of wire need to connect to the same place. Figure out ways to do that as neatly as possible BEFORE you melt any lead.
- Lay out all your components, measure where they should go. Make sure that there is room to actually fit all the components in your enclosure, that nothing touches that shouldn’t, and there is room for the jacks to fit into the plugs without wrecking anything.
- Drill and test-mount EVERYTHING before you start melting any lead.
- Label your jacks! I just wrote what they did (in, out, send, return) beside them in pencil inside the case. This WILL save you time. Make sure you turn the box over, so that you are looking at it the same way you will be using it when you label things.
- Go through and tin all your components. If you don’t know what that means, look it up.
- Measure your wire. Measure it again. Then cut it, then tin it.
- Soldering should be the fast part of the job. By the time you actually start melting lead, all your thinking should be done.
- If you are using a switch with lots of poles, plan the order in which you are going to connect things, so you don’t end up getting in your own way. You will probably want to connect the inside poles first.
- If you are using a two-part box like this one (Bonus hint: Don’t use a two-part box like this one), you might need to leave the wires a bit long so that you can put the box back together without ripping any connections out. It’s OK to go back later and shorten/redo the wires later, but start with them long so that you can get the thing working and check the circuit without wondering if you broke it by building it.
- Make really sure you know what side you want the LED on. I mean, what kind of IDIOT doesn’t do that?
I tested this with my beloved DOD Phasor 490. With the feedback knob set just right, it made a completely excellent whooping noise, which is pretty much unusable in any context in which I currently play.
That made it all worthwhile.