INTRODUCTION
This page documents my progress on building an opto compressor design by
Fred Forssell. There is a wealth of information spread out on the Prodigy-Pro Forum, but you may find it convenient to look here for some specifics:
DIY FACTORY - The FFOSC Project Lots of information
Forssell Opto Compressor The design thread
Official Forssell Limiter Build thread The build thread
For a start, this particular unit will be a mono version based on the board revision 1c from Tommytones, powered off of an external +/-24V PSU and will have a discrete output amp and LED metering. From there on, I will see about adding an input stage and maybe some other useful stuff like sidechain filtering. As the unit runs on +/-24V all 8 pin DIL chips are OPA2604.
CONFIGURATION
unbalanced input (10uF/35V cap to R43) >>
sidechain >>
discrete output >> balancing transformer (any 600:600)
metering: 10 element
LED meter
USEFUL INFORMATION
The following provides some infos found on the forum, I still have to verify some of it:
- R28: this resistor sets the maximum slope,
set to 100R
- U9: buffer,
only needed for stereo use
- changed R11 from 1k to
3k
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