Multibander

After doing the GssL 20th anniversary circuit, we decided to clean out the old, group projects from the PCB shop and see if we can come up with something new. We give you, the "Multibander". This circuit greets us with a single channel input, splits the signal 3 ways via a 6db/oct high pass crossover for a high band, a high and low pass for a mid band, and a low pass for a low band. The signals are sent to individual outputs, so you can interface any piece of gear on each band, then carry it back to one of the returns on the Multibander, where signals are summed into a single output. Essentially, you can build a multiband processing device with your existing hardware. As a practical addition, there is a bypass on each insert, as well as a solo listen function for each band. The board we layed out is mono. In the test build, we just paralleled two boards for stereo, and referenced the relays to the same switch.

The max amount of frequencies available depends only on the switch you use. For this, we use a Lorlin 2x6 on the prototype, and we overlapped a few frequencies to test its ability to work as a two way crossover as well (setting the frequencies identically, and excluding the mid band).

Docs Main board schematics here

PSU Schematics here

Panel files

Front panel here

Back panel here

BOM

Typed out BOM here

Carts

Reichelt, for 1 channel (x 2 for stereo unit) here

Reichelt, for PSU - here

Mouser cart - here

You can adjust the panel files to your liking, but note, if you want to use the PCB mount XLR, keep the measurements as is on the back panel. You can also do a mono version of this, but I have no validated file for it (lower the height to half, adjust, and check for clearance of PCB/XLR).

Frequency selection There is a public google sheet with a filter value calculator here Jot in the frequencies, and it will show you the resistor values needed, rounded to E96. You should not be able to edit the calculations, the E96 table, or the resistor value cells, but not 100% sure how cell protection is assigned ;)

Let us know if anything seems off! Gustav & Isak