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