[sdiy] LM13700 crossfade query

[Olivier Gillet]

Looks good to me. You can find a similar topology in some polysynths,
where each voice's VCA current output - just like the LM13700 outputs
- are fed straight into an op-amp in "transimpedance" configuration (I
think I've seen that on the ESQ-1).

As it has been discussed a few times here, you should keep the 2
traces from the LM13700 outputs to the op-amp as short as possible.

Olivier