After some absence from personal projects, I finally got around to soldering and testing my new Multi board for Eurorack. I think it’s a pretty special project, so I wanted to share it and see if people are interested.

What is it?

It’s a signal multiplier for Eurorack, which is to say that you can give it an input signal, either digital or analog, and it will give you anywhere from 2 to 16 copies of that signal.

What makes it special?

I built this module because I needed it and I didn’t see anything out there that did exactly what I wanted it to do. Here is a list of features:

All inputs are buffered. No need to worry about inputs affecting each other, or the rest of the system. Inputs can have very high impedence and very low output current and still work perfectly.

All outputs are buffered. This means that something downstream can’t cause problems upstream. For instance, you can plug one part of the output into a very low- impedence sink and it won’t affect the other half of the channel.

Inputs are chainable. So, if you plug an input into Channel 1, it can also be copied into Channel 2, which can then be copied into Channel 3, all the way down to Channel 8.

Sweet latch switches. Nice clicky feel, and it also can work as a mute for all channels down the device.

Versatile. You can use it as 8 x2 mults,or 4 x4 mults, or any combination you can think of.

Awesome blue LEDs so you can tell which inputs are chained.

Standard Eurorack power header.

Here are some pictures of the device and the build

Here are the unpopulated PCBs. They don’t look bad, if I do say so myself.

After an hour fidgeting with 0402s, I got to about here. Hey, Dawg. I heard you like op-amps. So I put some op-amps on your op-amps so you can buffer while you buffer.

This device has, believe it or not, 12 dual op-amps, and every single amp is used.

Here is what it looks like fully assembled. Well, assembled, but still no faceplate. I need to work on that. Looks pretty decent. The next pass will have a faceplate, and that will make it a lot easier to align the LEDs perfectly.

Finally, here it is being tested in my little rack. I LOVE the O’Tool from Jones Video. It’s the most useful thing in the world if you build your own modules from scratch. A bit pricy, but worth every penny, in my experience.

Anyway, here you can see the wave form. I’m using the Hertz Donut from Industrial Music Electronics as my wave source. I’m patching it to Channel 1 of my multi then out of Channel 1 into the O’Tool (grey cable.)

Then, I chain Channel 1 to Channel 2, Channel 2 to Channel 3, and finally Channel 3 to Channel 4, which is patched to the second channel on the O’Tool. Perfect wave reproduction, equal amplitude, and perfectly in-phase. I’m calling it a success at this point.