Hi John, Florian,

> > Does anyone know if there is any way to mod the VCA on the A-107 to
> > reduce the noise level
> To my knowledge the A107 is using a Curtis Chip CEM3372 which integrates
> VCF and VCA.

It is actually the CEM3379 which is used in the A-107, so the pin-outs for Florian's good ideas aren't applicable: the VCA 'in' is pin 13, and 'out' is pin 11; the 'out' however is a current, feeding an op amp virtual-ground summing node, so unfortunately you won't be able to measure any signal there.

However, it should be possible to take the signal _before_ the VCA, from jumper 'JP16' - this is hidden by the ribbon connecting the two boards, and the pin nearest the edge of the board is the signal output from the op amp summing the outputs from all four filter sections.

The signal paths are going through quite a lot of chips, so it might not be too much of a surprise that it picks up noise on the way: after the '3379, each stage is amplified (approx x10 last stage; x75 the others); then through the SSM2164 VCAs for the morphing; summed; then the '3379 VCA, and the final op amp converts to a voltage for output!

Tim