[sdiy] 8bits, 10bits or12bits DAC for a midi2cv converter?

[m.bareille at free.fr]

Hi Samppa,


> Pitch bend? ect. Marc How have You deald with such details?

One DAC is generaly assigned to the Midi notes messages with a 0..10V range ( 10
Oct on 7 bits generaly). It is DAC0->CV0 output

Another DAC, say #1 is assigned to read Pitch bend messages , still with a 10V
reference, and  summed to the CV0 outut op-amp with a 'divide by 10 factor'
resistor for example. So this give a 1V range  for the Pich bend =12 semitones
with a 7 or 8 bits resolution depending of the pitch bend messages source ( PB
can vary from a MIDI keyboard to another, if i remind well the
PB  can be encoded on 14 bits but this hi-resolution is rarely used fully ,at
least on old midi keyboards...)

Obviously changing this 'pitch bend DAC' summing resistor value change the pitch
bend range too, without changing the pitch bend digital resolution ( ie to get a
1 or 2 tones  or any other PB range... )

To add the Pitch summing resistor is an hardware option. It also require to
'sacrifice' a DAC to the Pitch bend ...

Another solution, good for modular systems, it is to use an external Cv mixer to
mix the notes CV with the Pitch bend CV...

With a 12 up to 16 bits DAC the pich bend can be added  internaly in digital
domain by the cpu before to reach the DAC, but it is another story ...

Each method have advantages and drawbacks... exactly like the use of various
DACs resolutions to solve the interesting problem of translating MIDI message
into CVs ...

Cheers,

Marc B.