altfidelity
Well-known member
I made GREAT progress yesterday. I made bunch of different mods, that worked (surprisingly) as expected and shown in LTspice model.
Most of them worked functionally as expected, but some were less musical and useful then others.
I tried relaxing the ratio with R27/R57 with 100k pot.
Increasing the threshold with R8/R41 with 10k instead of 20k resistor.
Bypassing diode D6 for for faster release action. worth it
Adding 1K pot after R22 resistor for fine tuning of the attack.
Replaced R6/R50 22K with a 100K resistor, for greater amplification factor of the main gain cell. worth it
The way I see it its fixed threshold design, and the threshold knob is actually input attenuator. The first gain stage (opamp + fet) work in sort of unity gain, when no compression is present. The most useful mod I did is replaced R6/R50 22K with a 100K resistor (also bypassing the diode D6). This by default amplifies the signal more and allows to drive the FET and side-chain harder. You still have input attenuator and output gain, so you still have all the subtle compression of the original design if needed, but you know have option to compress the shit out of drums.
The main problem with this design is ugly noncontinuous shape of attack. It create ugly spit/thump transients, that are very unmusical when you try to use slower attack times, for more subtle applications. It basically sounds shit when the attack is slower than instant. It does not create slower attack, it basically delays the attack that is still fast.
And you can even see it in LTspice simulations:
fast D&R attack (good)
slow D&R attack ( basically delays the attack that is still fast.)
In comparison with gSSL LTspice model that has "pretty" attack curves:
fast SSL attack
slow SSL attack
@gyraf @richiyobs @JohnRoberts Is there any way of reshaping the sidechain to make attack more "log/exp" shaped or is this just a inherent property of a FET design?
Most of them worked functionally as expected, but some were less musical and useful then others.
I tried relaxing the ratio with R27/R57 with 100k pot.
Increasing the threshold with R8/R41 with 10k instead of 20k resistor.
Bypassing diode D6 for for faster release action. worth it
Adding 1K pot after R22 resistor for fine tuning of the attack.
Replaced R6/R50 22K with a 100K resistor, for greater amplification factor of the main gain cell. worth it
The way I see it its fixed threshold design, and the threshold knob is actually input attenuator. The first gain stage (opamp + fet) work in sort of unity gain, when no compression is present. The most useful mod I did is replaced R6/R50 22K with a 100K resistor (also bypassing the diode D6). This by default amplifies the signal more and allows to drive the FET and side-chain harder. You still have input attenuator and output gain, so you still have all the subtle compression of the original design if needed, but you know have option to compress the shit out of drums.
The main problem with this design is ugly noncontinuous shape of attack. It create ugly spit/thump transients, that are very unmusical when you try to use slower attack times, for more subtle applications. It basically sounds shit when the attack is slower than instant. It does not create slower attack, it basically delays the attack that is still fast.
And you can even see it in LTspice simulations:
fast D&R attack (good)
slow D&R attack ( basically delays the attack that is still fast.)
In comparison with gSSL LTspice model that has "pretty" attack curves:
fast SSL attack
slow SSL attack
@gyraf @richiyobs @JohnRoberts Is there any way of reshaping the sidechain to make attack more "log/exp" shaped or is this just a inherent property of a FET design?
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FWIW back when I was designing companding noise reductions my design goal was to be as transparent as possible without spurious audible artifacts. There are multiple moving parts in dynamics processing so don't expect to find simple answers.
