Hi Roel

> Nop, your right Florian both are equal in volume only
> when they reached full gain (=10).

In my articles about the analogue synthesis I always explained, that the
VCA module should not be called amplifier but a level decreaser, because
the working range of the module is between "output is equal to input",
"output is less than input" and "no output at all". So there is never a
point, where the signal is amplified in the original meaning of the word
(="output is more than input").

> Before I forget the both in's were at position 8. And the
> general out also on position 8.

The basic level of the input does not matter. What matters should only the
ratio between input and output.

> But when I turn both in's (from the two VCA's) to 10,
> I immediately hear that the linear gives more power!

So this may be a different setting of the audiomixer, which is included in
the A130 or A131. Perhaps this is simply caused by the deviation of the
resistors in the mixer section. If it is a wished design, I would think it
more senseful, to have the A131 with more signallevel than the A130.

> Now, when I plug the low out of the A-121 directly in the
> input of the A-138 mixer (lin) the volume is cranked up
> several levels. How come

As far as I know there could be also two revisions of the mixers; the older
ones did not amplify and the newer ones had a smaller feedback resistor at
the summing amp, which causes some level increase, if the input is turned
up to 10.

I remember that some of the betatesters had the wish, that the mixer should
amplify. But this should be verified by Dieter.

Florian