“This is a Sequential Circuits Pro One synthesizer.
I am including a DI box in the package (as this eliminates audio hum).
The main circuit board was built in April 1982.
The serial number on the board and the one on the casing don’t match, which would suggest to me that the synth is a combination of two previous synths.
I have made a few improvements / fixes to the synth since I bought it:
A complete clean inside and out. All switches have been cleaned as have all key contact points.
Some capacitors have been replaced.
An internal ribbon has been replaced (bought from Wine Country Productions Inc).
I have bought wooden end cheeks for the synth, since these were missing.
I have also replaced a mod wheel (which was broken) with a clear acrylic wheel.
There is audio hum. Apparently, this is a very common feature of the Pro One and is due to a ground loop (an original design oversight).
The DI box eliminates the hum, and this is why I am providing the DI box with the synth.
I’ve tuned the synth using the variable resistors (pots). The tuning is pretty good across the keyboard, but will no doubt need readjusting from time to time.” Click here to visit listing on eBay