Rainbows and Unicorns? Cloning the Rainbow Machine

Earthquaker Devices has a lot of unusual modulation effects. I mean a lot of unusual modulation effects. One of the most unusual is the Rainbow Machine which is described as a "polyphonic pitch mesmerizer." It's a tough pedal to dial in, but it does have a fairly dizzying array of sounds on tap - with the pitch control being perhaps the most important. I'd received a request for a dinosaur version of the pedal, so I decided to take the plunge and see what I could make happen with it.

For this build I used the PedalPCB Leprechaun board. The effect is purely digital and it is based on a stock usage of the Spin FV-1 chip (as opposed to one that needs a separate EEPROM chip with algorithms). The Spin FV-1 is a surface mount chip, with a whole lot of connection points. Since I'm still developing my skills soldering SMD components, I went ahead and picked up one board with the chip already mounted, and then built a second personal unit where I intended to solder the chip myself. With copious use of flux, I managed to get the FV-1 on my board (below) down reasonably well, which may open the door to more SMD projects in the future.

The rest of the build follows my normal pattern using a mix of 1% metal film 1/4W resistors, film capacitors, MLCC capacitors, and electrolytic capacitors from Mouser. This one also have a few additional through-hole packaged integrated circuits which I socketed per my normal build technique. The board is fairly roomy as this pedal is designed for a 1590BB enclosure (I used a 1590BB2 as it has extra depth). 

There is a bit more hand wiring on this particular build than on many of my recent builds. In addition to the normal active / bypass stomp switch, the pedal has a "Magic" setting which is activated by a second stomp switch. That second stomp switch is hand wired, though it is only four connections (that being said, I tend to use aviation grade wire, and hooking up a stomp switch with solder lugs with aviation grade wire can be a royal pain in the butt!). Another feature is the expression jack. This feature allows you to connect an expression pedal to the effect to effectively control the pitch (spectrum) rather than adjusting the knob.

I wanted to come up with something suitably fun for the enclosure on this one, so I went with a very dazzling dilophosaurus - the Jurassic Park film variety rather than a more scientifically accurate one. The background imagery has light going through a prism to provide a bit of a throwback to the original "rainbow machine" name of the pedal.

In terms of sound - it is almost impossible to know where to start. Nothing that comes out of this pedal is ordinary or analog. You can get a pretty shimmery digital chorus if you set a lot of the knobs to noon and turn on the magic / dazzle - but from there it gets really crazy. For me this is an entirely situational pedal if you're trying to do some sort of specific way out there effect, but it is really cool nonetheless!