|This is a 1981 construction article from Modern Recording magazine by Jon Gaines. It provides complete instructions for building a full-featured noise gate. I built it years back, and can confirm it works reasonably well. Given the age of the photocopy, there was only so much digital tweaking I could do, but it is fairly legible. As with most of these scans, the PC mask may not be exact scale.|
If you have no experience with noise gates, please note that they are inherently "twitchy". You will usually have to fiddle with the attack and release/decay controls to reduce false triggering of the gate. If you hear certain types of buzzy distortion, that can often be a sign of mis-set controls. You may want to increase the value of the envelope follower (attack/decay) cap from 0.35uf to 1uf or so to smooth out the envelope ripple. Virtually every principle that applies to using envelope-controlled effects applies here too.
IMPORTANT NOTES ABOUT PARTS:
- The TL075 is a BiFet quad op-amp with a LM4136 pinout (different than a TL074). Pin equivalents for a TL074/LM324 pinout are pencilled in. Given the resistance values for most of the op-amp stages here, a 4136 may well perform better with respect to noise.
- There are plenty of other JFET's that can sub for the 2N5457, like an MPF102, 2N3819, etc.