via this auction
"Original vintage Prophet 10 with Wine Contry MIDI and Analogue Renaissance REV-1 downgrade installed in the lower board. With this 'downgrade' the CEM3320 VCFs in one of the two 5 voices board are replaced with the new SSM2040 VCF clones, like in the Rev 1 & 2 Prophet 5. This way you have both Rev 1/2 and Rev 3 filters in the same vintage synth. REV -1 downgrade also adds two new features not present in the original Rev 1/2:
- variable Q-compensation that restores the loss of bass when resonance is increased (14dB is lost at the onset of self-oscillation in the original filter design).
- the option to use the REV -1 as 2-pole filter instead of the original 4-pole configuration. Most non-linear effects happen in the first two filter stages, and the 2-pole mode lets you hear these effects unfiltered by the last two stages."
