> Hi,
>
> I'm going to start on this DIY synth shortly when the rest of the
> parts have arrived. I have a question about the voltages to some
> of the pots and where the voltages are taken from. I realise the
> kit is intended for experianced electronics people but after
> having made a few x0xb0x kits and Klee sequencer I'm not too bad
> with a soldering iron, just not that good with power to certain
> things :) The Doepfer synth kits instructions are pretty good for
> a beginner I feel, just need a few more instructions on voltages
> for people like me :D
>
> First off I'm using the Doepfer DIY Kit #1 PSU with the board at
> the moment and have connected this up fine.
>
> Questions:
> 1. The +5V to the Tune potentiometer (VCO CV_1). I assume this is
> taken from the +5V connector on the board and wired to the CW pin
> of the pot, the GND is wire to the CCW pin
> 2. Is the Fine Tune (CV_SUM) also wired +5V as above to the same
> pins on the board
> 3. What voltage is the PW pot wired to +12V
> 4. What voltage is the VCF Freq pot wired to
> 5. What voltage is the VCA Gain pot wired to
> 6. What are the seperate -5V/GND and -12V pins for
>
> and lastly :)
>
> Apart from what is specified in the doc files are there any pots
> which are specifically Logarithmic
>
> Thanks for you help
> Andy
> www.modularplanner.co.uk

Andy,

as you already mentioned the kit is planned for customers who are a bit
experienced with electronics and they would be able to answer these
questions to themselves.

All your questions refer to the same matter: the range of a control voltage
and the result of the parameter change in the corresponding unit. This is
interrelated closely with the weighting resistor of the corresponding
control voltage input. For example if the input is 1V/octave (as for the VCO
inputs) a CV range of 0...+5V causes a 5 octave range of the control in
question. If the control is connected to GND/+12V you obtain a 12 octave
range. But you may also use the summing inputs and add a resistor of your
choice to obtain the desired range in combination with the voltage range
that comes out of the potentiometer. If a potentiometer should be linear or
logarithmic is mentioned in the manual. But it is not mandatory in all
cases. E.g. audio attenuators at the VCF or VCA inputs can be linear or
logarithmic (though usually logarithmic versions are used for audio
attenuators). It depends upon your personal likings. For example I prefer
logarithmic pots for FM inputs of VCOs and VCFs (but not VCAs) as you then
get a finer resolution in the lower range. That's why we use logarithmic
pots for these functions in the DARK ENERGY. But some users were irritated a
bit as they'd expect linear pots for these functions. It's all a matter of
taste.

We cannot give a complete electronic tutorial in the DIY SYNTH manual. And
to speak the truth we also want to hold off customers from building a synth
from the DIY SYNTH board if their experience is not sufficient. This would
cause unsatisfied customers and even we would not be happy with situation.

I hope for you understanding.

Best wishes
Dieter Doepfer