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

[Oakley Sound]

This is a big topic and it has been covered quite extensively in the 
past, so it may be worth searching out the archives.

The key thing is not the number of bits available but the accuracy of 
the DAC. You can have 16 bit DACs with only 12-bit accuracy for example.

An eight bit DAC is fine if it is made to have sufficient accuracy which 
most integrated forms are not. I believe the worst case accuracy for a 
monophonic synth DAC should be 12-bits. ie. a 12-bit DAC with a INL of 
+/-0.5LSB is just adequate. Anything more and your ears will hear 
detunings at some notes, ie. the interval between adjacent notes will 
not be a acceptable semitone.

For a 12 bit DAC to work, however, you do need to select the DAC 
reference voltage [or output gain] to give you a 1 semitone step for 
every change of the seventh largest bit. The bottom five bits should 
held low.

For an 8 bit DAC you should make sure the accuracy of the DAC is at 
least 12 bits. The DAC-08 is not, in fact, its only accurate to seven 
bits as its native accuracy is only +/-1 LSB. AD make a better part that 
is 0.5LSB, I think its called DAC08HP.

There's some more information about this in my User Guide on the now 
defunct Oakley midiDAC.

http://www.oakleysound.com/mididac.htm

Tony

www.oakleysound.com