This compressor needs more controlls

[Domplotz]

Hi people
I got this schematic from a book. The design is quite simple, the signal goes through the vca, is been rectified, a cv is generated, that cv controlls the gain.
OK. What i don´t understand is how threshold, ratio and the timing is worked out here. The pot P3, right hand side in the middle sets the gain for the cv signal. The text sais this determines the threshold. P4 is supposed to controll the ratio between 1:2 and 1:10. Timing they say attack max 2ms, release 1,5sec.
I´m not really getting this. If p3 sets the threshold, that is a soft knee design, so the compression works from the lowest signal on with rising ratio, right?
P4, they call it ratio looks to me like the attack contoll.
What i want to have is the usual flexibilities you need to get those pumping grooves.

I want to controll threshold, ratio, if possible soft or hard knee as well as attack and release.
Attack/release, thats what we call a lag generator. So i guess since that cv-in of the 2018 is a high impedance point, r14 could be replaced with a pot and diode leading back to the out of ic2/2. Independant rise/fall.
But if those timings really controll the ratio as well than i´m not on the right track.
I thought something like this: Threshold should be some comperator circuit that turns the whole compression circuitry off as long as the (cv-)signal is below a set amplitude. Than p3 would set the ratio? p4 the attack?
I start to repeat myself, i think you get the confusion i have. Any hints?
I looked at the gyraf ssl clone. I must admit i don´t get how that ratio is working, but it looks to me like it´s controlling the cv gain. Looks also like that´s not all...
Cheers Robert

[wxn]

Though I may not be technically educatd enough but I don't see a log>lin converter there. SSM2018 CV has to be linear, this means that you'd need to make a logarithmic function or smth. Otherwise it won't behave like a traditional compressor. Or not as accurate at least.
There were a couple of chips specifically created for compressing uses. Try searching RANE schematic archives, might gice some ideas

[Brett]

Why anyone would want to scratch build a compressor is beyond me. However, if you choose that path, as this is not as common as other analogue stuff, to shorten the learning curve and get you something that will actually work and sound decent, get a THAT 4301 or similar and follow the application notes. They're not expensive chips even from Profusion and they sometimes turn up on ebay for less.

Personally I couldn't be bothered, and bought something secondhand and put it in the FX loop.

http://www.thatcorp.com/aneng.html