Crosstalk! Learn to live with it! If you don’t have the test discs, the easiest way to hear the crosstalk is by pressing the top most key on the keyboard. Crosstalk changes with the weather, basically- the light detector is very sensitive to temperature and atmospheric changes. The result is that adjacent tracks on the disc will bleed into each other. The top most key on the keyboard lies right next to one of the chord buttons, so usually you will hear that pattern bleeding through. The test discs were designed primarily to measure how much crosstalk you had on your optigan, but they weren’t much help in alleviating the problem!! Interestingly enough, I’ve found that in the Southern California climate, I can usually clear up crosstalk problems by leaving an Optigan in the trunk of my car for a day or so. (Basically this discovery was a fringe-benefit of laziness!!!) The bottom line is this: with an Optigan, your best bet is to simply wait a day or so until the problem magically disappears. Attempts to re-align the light-detector usually prove to be a frustrating waste of time, and often you will end up making matters worse by fiddling with it. When the Orchestron was designed, special attention was paid to the crosstalk problem, resulting in a more musically sensible track layout on the discs and a more easily adjustable light detector. But with the Optigan you’d better start getting used to the sound of your melodies played as parallel minor seconds!!