Idea: single vca based stereo panner

I just has an idea - would it be possible to make a planner using a single VCA? If one lets the VCA control the volume linearly for one channel, then subtract the result from the other, one would get louder as the other gets quieter. It could then be followed by two expo converters. EDIT: Not sure how I thought this could work, the expo converters would indeed increase the tops, but not linearly so we get distortion. Could the "Better balance control" ideas from https://sound-au.com/project01.htm be adapted somehow?)

There are some immediate problems with this - getting a correct 50% balance requires tuning, the expo conversion, if done using transistors, will require matched transistors which will also be heavily affected by temperature, and the audio signal must be unipolar or the transistors biased in a special manner.

But would it work in practice? That would be a fun little experiment :) not sure it will save us any parts compared to two lm13700 based linear VCAs controlled by a computer though.

EDIT: I've tested the LINEAR version of this and it works well.