Pendulum OCL-2 Side chain EQ
A quick soldering project to make 160Hz high-pass filters for the Pendulum OCL-2 compressor…
These fit inside a stereo plug (TRS) and provide a 6db per octave rolloff of lows on the compressor’s side chain EQ, so it doesn’t trigger so aggressively on low frequencies. It’s actually quite transformative, giving the unit a different gain reduction action.
From Greg Gualtieri at Pendulum:
"The input impedance of the sidechain ring input is 10Kohms. The equation is defined for R in ohms, C in Farads. Typical caps are in microfarads, or 1x 10 to the-6 Farads. So, if you connect a 0.1 microfarad (uF) cap across the tip and ring of a stereo plug, you get a 6dB per octave rolloff at 159Hz. For a 0.05uF (two 0.1uF caps in series), you get 318Hz. And so on. No resistors needed. The smaller the cap, the higher the rolloff frequency. The audio quality of the cap doesn't matter, since it's in the sidechain."
You can change the capacitor size, but 160Hz seemed the most generally useful. Parts used were a Neutrik NP3X-B stereo plug and a Nichicon 0.1uF capacitor…
There was an online discussion on the topic here.
