PedalPCB 401K Compressor/Keeley 4 Knob Compressor

[OD is Glorious]

Build Rating

5.00 star(s)

Works as intended and I guess it could also be a nice boost. The sustain knob is the magic - it adds some dynamics and it is good for soloing. I cannot sense big changes when using the clip knob - Keeley says it is a sensitivity control, meaning you can use this circuit in your studio to run keyboards, drum machines, drum mics, even master recordings and other line-level uses. The attack knob does not do much for me - Keeley says it is for bass players with high-output active pickups or active pedal boards with buffers - not me. I think you could use this as a boost pedal because the circuit does have headroom and the level potentiometer brings it - unity is below 11 o'clock.

I used a bare aluminum 125b enclosure with a waterslide decal. I then used the 2k matte clear. The knobs are Davies 1510 and I used the black washers and nuts under them. The LED is a 3mm waterclear in a clear freznel. I used a PPCB top jack plate and Switchcraft jacks. I used WIMA caps for all but the 1N and I used mostly gold electrolytic capacitors. I used a feather click footswitch from LMS with a PPCB LED brightness control breakout board so I could move the LED to the footswitch area. For the LED I used a 5.6k resistor and a 5k trim pot. No oddball parts besides the LM3080 which is now available as a CA3080. There are some

This is an easy build which produces a great circuit.

Notes

1. No more LM3080 available but you can find CA3080AE at Stompbox for $10 or CA3080E at Small Bear for $8
2. Potentiometers include C250K C500K B50K and B250K
3. WIMA capacitors are not required... they are expensive and bougie