Insert Compressor Pass band help

[goldstache]

This is a circuit based on a guys LA-2A Lite compressor. My finished circuit is the schemo I landed on. Wanted a +4 out as well.


Since it's bipolar supplied, there's not much in the way of frequency selection for pass band, direct coupled and all. I'm finding that my circuit sounds the way I'd like it in an insert situation. But not so good with lowZ source.
I'm pretty sure my mixer inserts are 10K send/return.
The + pin pulldown on input (buffer/preamp) is 220K. After noticing the disparity of freq transfer, when using a LowZ source, must be from Z bridging.
I played around to try and get cutoff into a spot that felt right.
Basically calculating cutoff.
So shunt cap at max gain, cutoff was around 4k with shunt cap value of .0015uF.
And at min gain, cutoff around 14K.


So chasing the treble pass band, in regards to gain, dawns on me why so many preamps have a signal level control (V divider) up front of the circuit, and then the stage has fixed gain/fixed pass band window.
To keep response steady and signal voltage increases.


Since this is a limiter/comp, I want some signal scaling up front, to push more at times.


Ultimately I just want more understanding of what I'm up against here.
Opamp gain and Freq pass bridged vs hiz Z input. (sounds flat-ish with 10K source)


Sure, could use caps to stage isolate, but I'm trying to limit phase shifts, and keep an eye on offset, as there is no servo setup. So far all outs have been under 4mvdc.


I tried R1 as 10K to brickwall the impedance, but only a little more settled with regard to pass band.
Have a look, share anything that comes to mind. Thanks