Thursday, January 1, 2015

How To: Make a Stupid Easy Re-Amp Box and Run Everything Through Your Guitar Pedals

Guitar pedals are awesome. They're like audio cupcakes: there are nearly infinite varieties, and like the sugary treats ... no matter which one you choose, even if it's not exactly what you're looking for, it's probably gonna be fun.

The only problem with guitar pedals is that they ... you know ... only work with guitars ... but what if that wasn't the case? What if you could run toy keyboards through them? Vocals? How making 'bout making the rattiest, nastiest snare in the world by running it through your fuzz pedal(s)?

For instance, running a stylophone through an auto-wah to make a surprisingly familiar synth sound:

All this and more is possible, my peeps, through the use of what is known as a "re-amp box". Which you can buy for a lot of money. Here's the thing though, at the end of the day a "re-amp box" is simply this: it converts a line-level signal to an instrument-level signal.

Boom, that's it. It takes a high signal level and reduces it. Many of those expensive boxes do more, but if you want to run non-guitars through guitar pedals, that's really all you need it to do.

It is a ridiculously simple circuit, and if you're the handy, adventurous type, I suggest making yourself the "New York Dave" box. I almost did this, in fact, I'd already got all the parts in my shopping cart on mouser and edcor, and was about to checkout. I was about to spend about $80 in parts including shipping, and a lightbulb went off.

This is a thing that exists: the Behringer Ultra G DI Box. It costs about $40 or so, but it's designed to do the opposite: take an instrument-level signal and amplify it to a line-level signal. That would be the end of it, except for these two buttons:

that's -40db of gain reduction in -20db increments!
With that much gain reduction available on the input, you can certainly plug a line level into the input and get a passable instrument level through the output. Except for one more problem (well two more problems really). It starts with the output connector ...

Thank Gawd it Takes Batteries, Y'all
So ... yeah, two problems:
  1. The output is XLR.We want to feed the output to a guitar pedal, so that's not gonna fly
  2. It's not passive (it needs a power supply), and that power supply is phantom power.I cracked it open. There's a couple transformers in there, and a tiny circuit board (one presumes which runs the "virtual 4x10 cabinet simulator" -- which before you gong that, actually does some interesting things when you turn it on reversed like this). Anyhow, yeah it needs power, and it's designed to suck that power from the board you plug it into. That's not a problem because ...

  3. it takes batteries!
So, I mean this really isn't even a hack. All you need is an XLR to 1/4 inch adapter and a 9V battery.

If, like me, your DIY ethos remains unsatisfied, you could always make your own XLR->1/4in. adaptor ....

things are about to get nerdy ...

I discovered that the rubber sleeve at the end of a female Radio Shack XLR connector is just the right size to grab the innards of a female Radio Shack 1/4 inch connector. Check it out:

And the finished product:

Happy Re-Amplifying, and Happy New Year 2015!