Doepfer

Hi Roel 

> Fascinating to hear that when you reach the highest position
> on the input of the 138 mixer, a small feedback resistor comes
> to action on the new models, compared to the older ones, which
> didn't amply!
This is a misunderstanding. 

An signal transfering operational amplifier circuit _always_ uses
feedbackloop.

                  +-RRRR-<<-+
                  |         | <............This is the Feedbackloop.
                  | |\      |
sig.in >>--RRRR---+-| \     |
                    |  \    |
                    |   +>>-+-->>---Out
                    |  /
                  +-| /
                  | |/
                  |  
                  |
                Ground
                 
      
          RRRR means Resistor
          >> shows the direction of the signal flow


As long as the both resistors have the same value there happens no
amplification. If the resistor in the feedbackloop has a larger value than
the input resistor, then the circuit will amplify the signal.


 
> When I understand the lin. versus exp. bit, and I extrapolate that
> to the lin and exp. mixer, 
Lin / exp for the mixers only means, that the potentiometer have
logarithmic or linear characteristics. You simply can make on eout of the
other if you exchange the pots.


> am I right to say that one type of mixer
> is better to use for audio signals and the other for cv?
That is right. 


Florian