[sdiy] newbie question

[Bob Roesler]

Hi all,

I have it in my head to build what I will call here an adder/multiplier.

It would consist of identical A and B sides: a four input inverting A mixer,
and a four input inverting B mixer. A linear VC crossfader would linearly
mix the between the two upstream summing circuits.

Pretty straightforward.

The mixer part is pretty, there are alot of schem's out there I can learn
from. 

The linear crossfader is my question.

Is the best thing approach to make two separate linear VCA's using
complimentary VC's and sum the outputs? Or is there a cleaner way to build a
crossfade circuit?

I should say that my primary CV's would be +- 5volts (an oscilator), rather
than a positive only signal (like an EG).

This would be my first DIY project (tho I've built a couple of other
people's designs), so please understand I'm starting at a pretty low level
here.

Thanks in advance.

Bob