MATRIXSYNTH: Prophet-5 Analogue Renaissance Rev-1 Downgrade

Sunday, December 12, 2021

Prophet-5 Analogue Renaissance Rev-1 Downgrade

video upload by synthlegends

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"Some tweaking and demonstrating the downgrade mode of analogue renaissance.

What I like in this mod is the boost switch, called Q-compensation and 12 dB Filter, which makes much power even with high resonance in the filter. You can listen it in the first patch in this video. The recording was made without processing, effects and just raw into the audio interface in mono. For further information go on the website of analogue renaissance.

I kept my curtis filter chips, so I can built this prophet everytime back in the original state.

Here is the description from the website of analogue renaissance:

This modification for the Sequential Circuits Prophet-5 reverts the Rev 3 sonically to the earlier, much bigger-sounding Rev 2! The two Prophet 5 versions sound different due to the nearly complete redesign of the voice architecture to use Curtis’ CEM chips instead of Dave Rossum’s SSM chips for the transition of the Rev 2 to the Rev 3 model. This difference in sonics has made the Rev 2’s more desirable - and significantly more expensive. Fully working prototypes have been built and tested, and have the following features:
No mods to the Prophet 5 PCBs are required.
A REV -1 simply plugs into the IC sockets, replacing each CEM3320.
Only 1 extra wire for the -15V supply needs to be soldered.
Electronics have been added that cancel out the pollution from the CEM3320’s level shifting circuitry. The little that remains (30 to 100dB attenuation depending on frequency content and Prophet component tolerances) is also moved entirely to the filter's input. So, it get's further attenuation of 24dB per octave beyond cutoff.
The input signal has been increased a bit, since the 2040 likes to be driven a bit harder. This is no issue for the purists as it can be attenuated in the ‘mix’ section of the prophet-5.
By design the SSM2040 is also self-limiting, so the output level has been increased a lot as ample headroom was available, and this gives a much better signal-to-noise ratio and dynamic range.
REV -1 also adds two new features not present in the original Rev 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.
The combination of these two extra features will make a Prophet 5 sound absolutely monstrous!
Switches to select 2-pole or 4-pole mode and the amount of Q-compensation will be included with mouting hardware.

Thanks for watching and listening."

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