Reverberation
“In the vacuousness of space, no one can hear you reverb.”
Wait, what’s that? Vacuous doesn’t have anything to do with the lack of air in space or the suction created by my shop vac? It just means “marked by lack of ideas or intelligence; stupid, inane”? Damn it. I knew this would happen. Too late to re-make the enclosure now. Oh, the bitter petard of irony upon which I have hoisted myself!
We hear reverb all the time. When something makes a sound, it is reflected off of everything around it, with each bounce taking a slightly different amount of time to reach our ears depending on how far it had to go. The combination of all of those short delays give us a subtle sense of space that we don’t usually notice. Although when it’s taken away, people tend to get wildly uncomfortable.
When recording music, at least when recording with mics, the room reflections are often a big consideration in how things will sound. And then sometimes, an artist may want to introduce a ridiculous amount of unnatural reverb, and for that, we have pedals (among other things).
Details
I have avoided making a reverb pedal for a long time because it seemed like it wasn’t easy to do with the tools at my disposal. I pretty much only operate in the analog realm, and analog reverb usually involves some physical vibrating object, like the literal springs in a spring reverb tank or a huge piece of sheet metal in a plate reverb. When it gets down to pedal size, most commercially-available stuff is digital, and the best of that is often based on custom algorithms that are beyond my scope and interest.
But there is a middle ground. There’s an integrated circuit out there called a PT2399 that is a “delay on a chip.” It’s technically digital, but it can be treated as if it were an analog bucket brigade delay—it’s self-contained, with its own digital to analog converter built-in, and doesn’t require any external hand-holding or coding. A few of these working together, running at slightly different (short) delay times, can make a reverb effect, and it turns out that someone has packaged that configuration up with some special sauce into a single device, popularly known as a “Belton Brick.” All reverbs built around Belton Bricks start off with a similar character, so my next thought was how to make it weird.
Vacuous uses a PedalPCB Gravitation circuit board (inspired by the EQD Levitation) which uses the Belton Brick. The most interesting thing about this circuit to me is the Regen knob (they call it an “Atmosphere” knob, but I didn’t find that name helpful). It sends some of the higher frequencies coming out of the reverb back into the reverb, which adds a cool sort of ringing sound to the reverb tails at moderate levels. When it’s cranked all the way up, it will start feeding back on itself and get louder and louder, like a runaway diesel engine that has decided to start consuming its own crankcase oil as fuel. While this is a cool effect, it’s a little hard to control, so I had the idea of adding a “runaway” footswitch that would short two pins of the Regen potentiometer together, essentially diming it on command regardless of the position of the knob.
I initially had it in a 125B-sized enclosure, which is what the board is designed for, but there was no room for a second footswitch. My first stab was to simply add a jack so that I could send the runaway functionality to an external switch (in the style of the Germanium Switch, but momentary instead of latching). This was a terrible idea. For one thing, it’s all in the signal path, so running wires outside of the case to an external switch probably would have made it a lightning rod for picking up unwanted noise from the environment. More importantly, my 1/4″ jacks expect the sleeve to be grounded, so I was grounding one pin of the pot to the case, effectively disabling the Regen knob completely.
My second attempt was to repackage it in a 1590BB enclosure (I assume the “BB” stands for “Big Boi”) where I would have enough room for two switches and could keep everything inside the box. Given my assumptions about how Big this Boi was, I didn’t bother to measure whether the board would actually fit in there with the switches, which it didn’t. I then turned to that old secret weapon of the precision electronics world: a Dremel with a cut-off wheel. Removing large chunks of the circuit board, including some with traces that I was hoping to use, was perhaps not my finest hour, but after some trial and a lot of error, I got it doing what I wanted it to do.
Vital Stats
Sound
The Belton Brick is often described as having a sound like a spring reverb, but I’m not sure I hear it. To me, it’s its own thing, with elements of nonspecific artificial reverb and slapback delay, and I’m good with that. The following sample has two parts:
- Part 1: Emomaster > Vacuous > Fender Deluxe Reverb (with the reverb turned off). There’s no editing here…for that first stab, I’m holding down the Runaway switch, then I let it go when it starts to get crazy and continue on in one take.
- Part 2: My 000, recorded with an SM57 on one track, plus a second track using the pickup output into a Baggs Para Acoustic DI > Vacuous > George Washington Slept Here > Vox-flavored DI, kind of like an off-brand Kevin Shields/”My Wounded Secret Santa” thing.
