Removing the EP-4 compressor board
A good number of the early EP-4 Echoplexes in the seventies had a compression circuit board installed. It was rushed into production and was an abject failure. A lot of people complained about how it negatively affected the tone of the Plex, and they stopped manufacturing them with the compressor installed. They even added a page in the manual stating how to remove it.
Fortunately it is an easy modification to remove the compressor board. For all you EP-4 owners I reproduce it here. Just in case the text is not legible, here are the instructions:
- Cut the +22V wire and ground wire (Both brown).
- Unsolder output wire (Red) noting where it terminates.
- Unsolder input wire (Bare)and remove board.
- Connect input wire (Bare) where output wire (Red) was removed.