Doepfer

> Thanks for the reply, yes i did look at the 132-3 but i simplt dont have
the
> rack space, i need to add 4 vcas. Changing the parts is no problem (i do
> this all day at work) Are you able to let me know a parts list and which
> need to be changed.
>
> Paul

You do not simply have to change parts but to built a exponential current
source which you can find in an electronic schoolbook (e.g. Tietze/Schenk
Halbleiter Schaltungstechnik in Germany, but I'm sure there are many English
books available too). Sorry - I don't have the time to write a detailed
explanation how to do this as it's not that easy. In any case you have to be
experienced with electronics. The exponential current source circuit is used
in most of the CA3080 based filters and exponential VCAs and you will find
it in the internet (e.g. http://www.musiksynthesizer.de/?p=84). You may even
use the exponential current source of the VCF in the Oberheim SEM module
which can be found also in the internet.
If you search e.g. for "exponential current source" or "exponential
voltage-to-current converter" in Google or Wikipedia it should be no problem
to find the circuit.

Best wishes
Dieter Doepfer