Wednesday, March 3, 2010

DIY Audio Compressor: Part 1, the plan

After finding myself often wanting of an analog compressor in my rack of gear, I ran across the simple compressor design from the old Electronics Projects for Musicians(EPFM) book. It uses a couple op amps and a Vactrol (or LDR Optocoupler) to compress the audio signal. I was able to find a source for the vactrols through Allied Electronics.However, one of the op amps (RC4739) had fallen into obsolescence since the publication of these plans. After poking around the web a bit I found that the NE5532 seemed to work well as a general purpose audio op-amp, and had been used successfully in many of the EPFM plans. The caveat? The 5532 is an 8 pin DIP package, whereas the old 4739 was a 16 pin DIP, this single detail renders the PC board layouts provided in the book useless, and therefore in order to finish my project on a PC board, I would have to re-work the schematic and pcb layout to fit the new parts, I've since completed the schematic and hope to have the layout done and ready for etching (using a cupric chloride bath [Instructable]) soon. I've included the reworked schematic bellow for anyone else who may be interested to enjoy. Schematic and board done in KiCad

No comments: