OTA HPF Proto

This is a reference to my previous article about 24dboct-high-pass-filter. I built this two-layer proto of that circuit and it works great. Front panel layout is different because here I have a dedicated layer for pots, switch and connectors where I have more freedom on placement of components.

Crumar Performer

I have been repairing my Crumar Performer string/brass synthesizer. One zener-diode was dying and made the master-oscillator to change the pitch randomly. Now this is fixed and it's time to make some modifications. I replaced the MK50240 top-octave generator with FlatKeys replacement box FK50240. This box has 12 synthesizers that create the desired notes from the master clock with a worst case error of 0.00005 Hz. There are also some extra features switches (scale,transpose,octave) that you can activate if you want.

Other modification comes from SoundDoctorin in this "Crumar Performer easy modification for release envelope" video. In the original Performer when you switch the brass-section on it kills the sustain on both brass and strings. With two switches you can choose from three options:

1. original setup where brass-section kills sustain on both brass and strings
2. Sustain works for brass-section but kills the strings sound
3. Sustain works equally for brass- and strings-section

I think the third option is most useful. Brass section adds nice fatness to the string sound.

P621-board where is the brass-switch. The white/black/red cables goes to the both separate switches.

Explanation of what to cut and where to connect the switches.