![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvnoNGedPugPa3Z8meP_KnJw7TLFdDcmQ-FxhOHLd1wQiZuxjbG8Hybt5YTbf66Ljavs72SjvWUiuUYPWlKL8iD6gtChlENfcxqNTT04SR9lLN7_Ioc5Nv9O6633TXJyij8Jb1UTqsd5Ho/s400/5532-compressor.jpg)
Dana Simmons is a professional audio engineer and technology consultant and dabbles in instrument invention, synthesizer construction and other experimental music and technology related projects. Here he rambles about his recent projects and such.
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
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvnoNGedPugPa3Z8meP_KnJw7TLFdDcmQ-FxhOHLd1wQiZuxjbG8Hybt5YTbf66Ljavs72SjvWUiuUYPWlKL8iD6gtChlENfcxqNTT04SR9lLN7_Ioc5Nv9O6633TXJyij8Jb1UTqsd5Ho/s400/5532-compressor.jpg)
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