> the voltage inverter, combined with the inverse output of an adsr, was

only a next-best

> way of geting an envelope into negative voltages. what it doesn't do,

however, is enable

> the adsr curve to cross the zero line - the whole time you're in either

the negative or the

> positive. since an amplifier only multiplies and therefore cannot enable

this zero crossing

> (or am i being dense here ) it's the offset that i'm interested in.

But for this function you have a control at the module (for most modules)
that is controlled by the ADSR:

e.g.
Frequency control for filters
Initial gain for VCAs
(coarse) tune for VCOs

For (nearly) all modules each CV controlled parameter is already equipped
with an offset control. That's why I still do not understand the necessity
for an external offset module (with a few exceptions like the A-132 or the
limited tune range of the A-110).

If you have an external offset module and adjust the offset control it's
exactly the same as if you move the corresponding control of the module as
all the control voltages are added up. The only reason could be that you
want to have this as kind of a remote control. Otherwise you will have two
controls for the same function.

Best wishes
Dieter Doepfer