Doepfer

Hi Stuart,

> first question to florian (or anybody that has his book griffbereit):
> on page 32 of your book "synthesizer" you have a simple diagram of a
> control voltage generator, each resistance corresponding to one key on
> the keyboard. what would you recommend as a suitable value for the
> resistors? and should i be using 5v as shown in the previous diagram,
> or 12v as stated in the text?
The Resistors depend on the range of the keyboard and the used voltage.
If you want well tempered tuning, then the voltage 'around' one resistor 
should have 1/12th Volt.

Exmaple: You provide 5 Volts, the keyboard should have two octaves. Then 
it might look like this:

          R1    Rx    Rx    Rx           Rx    Rx    R2
Ground--RRRR--rrrr--rrrr--rrrr--[...]--rrrr--rrrr--RRRR--+5V

The Resistor R1 should have 120 kOhm, R2 should have 240 kOhm, each of 
the 24 Rx's should have 10 kOhm. The lowest "key" will be between R1 and 
the first Rx and will provide 1Volt.

> secondly, i intend to produce the gate by simply putting the control
> voltage through a comparator - everything above 0v opens the gate.
> does anyone foresee any problems here?
The lowest note must provide more than 0 Volts (and it should be 
noticable above 0 Volts to prevent erronous triggerings)

> and any other problems i've overlooked?
You need also a sample & hold to store the keyboard after you released 
the key. The S&H has to be triggered by the gate.


Florian