L´Andratté
Well-known member
Hi everbody!
It is not just courtesy of me to tell you, I like this forum and it´s, hmm, inhabitants? ;D
You know, I have become one too...
I have just posted in the documents section the schematic of the Roland SIP 301, an middle aged bass preamp, that I own and love. That is especially because of the brilliant optical compressor.
http://www.groupdiy.com/index.php?topic=45158.msg677240#msg677240
(upper right)
Now I would like to build me a standalone box of that, feat. also variable time constants (lacking in the original, but very useful e.g. for guitar-sustain).
But there are some things, that I don´t understand really:
there are three paths, one the gain cell, then the (feedback) sidechain path, but then also some kind of dry mix, regulating the ratio - called ´Dynamic Range´. This is mysterious to me as it is also contributing to the sidechain,
upping it´s gain when the threshold is reduced.
I just can´t wrap my head around it, but I´d really like to, so please someone likes to explain to me?
I know that you can
Another thing: per Vactrol application notes the two optos should give different responses, one being a voltage divider, the other in the fb-loop of noninv. op-amp. Of course these are not vactrols, so this is maybe dead end-thinking (or >>THE SECRET OF THE SIP<<)!
This is the page I got the service manual of, it has also some nice demos:
http://www.joness.com/gr300/SIP-301.htm
Cheers, L´Andratté
It is not just courtesy of me to tell you, I like this forum and it´s, hmm, inhabitants? ;D
You know, I have become one too...
I have just posted in the documents section the schematic of the Roland SIP 301, an middle aged bass preamp, that I own and love. That is especially because of the brilliant optical compressor.
http://www.groupdiy.com/index.php?topic=45158.msg677240#msg677240
(upper right)
Now I would like to build me a standalone box of that, feat. also variable time constants (lacking in the original, but very useful e.g. for guitar-sustain).
But there are some things, that I don´t understand really:
there are three paths, one the gain cell, then the (feedback) sidechain path, but then also some kind of dry mix, regulating the ratio - called ´Dynamic Range´. This is mysterious to me as it is also contributing to the sidechain,
upping it´s gain when the threshold is reduced.
I just can´t wrap my head around it, but I´d really like to, so please someone likes to explain to me?
I know that you can
Another thing: per Vactrol application notes the two optos should give different responses, one being a voltage divider, the other in the fb-loop of noninv. op-amp. Of course these are not vactrols, so this is maybe dead end-thinking (or >>THE SECRET OF THE SIP<<)!
This is the page I got the service manual of, it has also some nice demos:
http://www.joness.com/gr300/SIP-301.htm
Cheers, L´Andratté