Compressor based on Ross circuit with modifications
This is my first Aion pedal build. I appreciate the level of detail in the build notes. It really made the build easy. I had never used a compressor on my rig before and I wanted a good sounding compressor at an affordable price, so the Ross compressor circuit caught my eye since so many people claimed to like it.
For this build, I wanted somewhat of a vintage look and feel. I used a powder coated 1590B style enclosure in burnt orange and used Davies 1400 style cream knobs. This was also my first time using a water slide decal, finished with a clear coat. I like the look of the LED bezels, so I added one of those as well. I can’t stand the white washers that come with the 3PDT foot switches, so I replaced it with a metal flat washer for a cleaner look. The treble switch is just an ON/ON SPDT (instead of ON/OFF/ON), so it only allows two different tonal options. But, I prefer the simplicity of two options vs having to decide between three, anyway. I decided against using the provided lock washer on the SPDT switch just because it looked a bit unfinished on the front since you could still kind of see the teeth – so I only used the nut and very carefully tightened it so as not to scratch the decal with the wrench.
Modifications or part substitutions
– I used the 150k reverse audio pot for attack control. As you can see in the photos, I used a solder-terminal pot but soldered thick solid-core (18 GA?) wire onto each lug, and bent them in the same shape as the PCB mount style pots’ blades. This just made it easy to solder in the same way as the other pots, instead of using wires for just that one pot. Since the wires obviously don’t have the same “shoulder” like the PCB mount pots do, I just put some electrical tape on the backs of all the pots to prevent shorting on the back of the board, in case I pushed the board too far down before soldering. Worked great.
– I used an ON/ON SPDT treble switch instead of ON/OFF/ON. I didn’t populate the board at component label “C9” (left it empty). Instead, I put a 1nf cap (“stock” value) on CX3, and 470pf “471” cap on CX2, which is somewhat between the values of the two caps for the treble boost options described in the build docs. If anything, I feel like the 470pf cap might be a bit too bright for my taste, although not extreme, but I may consider bumping it up later. The stock value 1nf cap sounds pretty good in my opinion – seemingly unaltered from the bypassed tone, to my ear. So switch up is the stock 1nf and the switch down (toward the word treble) is the 470pf.
– I used a 150pf capacitor for C1, as mentioned in note 4 of the build notes.
– I used a 200 Ohm trim pot for the input trim control.