The trick fast attack circuit depends on the direction of side chain voltage moving for transients. The 2M pull up resistor creates a current threshold that the normal fast attack tracks when current (through D12 and R5) is below that threshold. When that current exceeds the 2M current, the op amp U1A disconnects from the 0.1uF and becomes 10x faster controlled by the 0.01uF cap. During this transient duration the 0.1uF charges through the 2M, but not much and after the transient subsides the side chain has not been pumped by the transient. The gain reduction happened but the side chain was not distorted like an actual fast attack would.bluebird said:Hmmm, The diodes labeled attk and release on the schematic are reversed, I just cut and pasted that schematic together. John had them like that because he wasn't planing the inverting threshold stage between the RMS and his circuit. Regardless, its just a matter of adjusting the resistors to the opposite diodes for attack and release right? Or does the CV polarity change the way the SVF works in general?
If you flip the polarity in front, you needed to flip the uber-fast attack too.
As drawn my SVF smoothing circuit should be unity gain for DC voltage.Would this circuit work after the threshold op amp, or right after the RMS detector? I will definitely breadboard this!
Ok I will try that. For some reason (when putting Johns circuit directly after the RMS detector)I am having trouble with over all offset voltage reaching the VCA and skewing the overall gain extremely.
If that is boilerplate limiter from THAT app notes it should be OK... I never made a THAT limiter. The smoothing circuit is non inverting unity gain, so order of the two circuit blocks in series should only change dynamic behavior, not functional operation.So the schem below should work correctly? I didn't try the threshold circuit after like that.
JR