Doepfer

> hi all,
>   
> the important (and relevant to Doepfer A100) question:
>  
> since it looks like (to my ignorant eyes) that the SH7 
> 'pedal vcf input' (seems to be powered) works like a simple
> variable resistor (i guess that i can
> simply connect a variable resistor to this input to change the
> filter cutoff),
> could i use the Doepfer A101-9 Universal Vactrol module, to
> operate the SH7 filter without any modification to the synth?
> (using the 'vac
> out' connected to the SH7 'pedal vcf input')
>  
> here is the link to that module:
> http://www.doepfer.de/A1019.htm
>
> here is a link to the SH7 service manual (thanks
> CEM3374 !) :
>
> http://www.cem3374.com/docs/Manuals/Roland/SH-7_SM.pdf
>
> (check page 24 and the vcf circuit page, to see how
> the pedal input is...)
>
> if this cannot be done, any help on converting the SH7 pedal vcf
> input to a regular cv input?
>
> many thanks in advance for your help!
>  
> best regards,     :-)
> Bakis.

Hello Bakis,

the vactrol output of the A-101-9 is completely separated from the A-100
(even no GND connection) and can be treated as a passive foot controller.
Using it as a substitute for a foot controller (variable resistor version,
not suitable for voltage divider versions with 3 terminals) should cause no
problems. But it  may work opposite depending upon the circuitry (the SH-7
schematics are very confusing, page 24 has a lot of terminals that refer to
terminals of other pages). But nothing can be damaged.

Best wishes
Dieter