Florian:

thanks for the very detailed instructions, much appreiciated...i again tried calibrating one of my A110's this morning and got much closer...i''ll try the other out tomorrow using your instuctions...

thanks again,
rg


----- Original Message ----
From: Florian Anwander < Florian.Anwander@... >
To: Doepfer_a100@yahoogroups.com
Sent: Thursday, January 10, 2008 8:48:55 AM
Subject: Re: AW: 1 A110 calibration help needed

Hi Ross

> i checked the MPU 101 and it's putting out solid 1 v/oct, i'll start at 1 volt and attempt adjustment of the octaves from there...where should i set the VCO high end trim when adjusting the octaves, and to what degree will it affect the octave adjustment in other words, if the high end adjustment is out (and it is at this point), will it be impossible to adjust the octaves

This is my procedure as I tune VCOs (it is a bit different from the most
descriptions because it attaches some value to the fact that the lowest
note MUST read real 0 volts at the summing point of the VCOs CV-mixer).
Here we go:

- Set from MPU101 that way, that it reads 0Volts; the MIDI note played
for this I will call "lowest note".
- Connect the MPU101-CV with CV1 of A110.
- Set tune (front) to an extreme position (so it cannot move occasionally) .
- Set VCO-Offset (trim pot P6) that way that Pin 2 of summing Opamp 1
reads really exactly 0 Volts (setting the rotary octave switch may be
required). After that try not to touch or move the front tune pot.
- Set P8 (high end trim) to center position

Now play 1/2/3 octaves up from this lowest note on your MIDI-keyboard
and adjust P7 until the A110 playes these three octaves in tune. It does
not matter which absolute note this is (must not be a C), but it must be
clean octaves. Do not try to adjust more than 3 octaves!

Now remove the external CV from CV1, and use instead the rotary octave
switch from the front for 1/2/3 octaves up. If the octave switch does
not produce clean octaves, then adjust P5. Do NOT touch P7! Do not try
to adjust more than 3 octaves!

After the octave switch is adjusted. Play 4 and 5 Octaves (or switch
them with the octave switch) from the lowest note and if required adjust
P8. Do neither touch P7 nor P5 for this.

For all these settings you may control at Pin 2 of summing Opamp 1
whether your 1V/Octave is still true at this point. It is very
recommended to monitor this - especially to check, whether your lowest
note still are exact 0 Volts.

Finally:
If all this is done. Adjust P6 that way that the vco is tuned for the
notes you are playing on your keyboard.

Florian



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