![]() ![]() Its not accurate enough, and it either produces a lot of high frequency noise or a very slow slew rate (or both!) depending on how you filter it. Kssm wrote:and I'm trying to get the best frequency value to generate useable, steady pitches.ĭon't use PWM, especially for pitch CV. To get to 10 bits you need then you start needing 0.1% resistors which are expensive and to get beyond that you need better tolerance which is seriously expensive and totally pointless because the cheap DAC will have individually laser-trimmed resistors on the package and the entire chip costs less than two 0.05% or better resistors! This is a really bad idea, because if you need 8 bits or less then just use a cheap 8-bit DAC. There is lots of mention of making resistive string DACs. Divided by 256 and assuming a theoretically perfect DAC, that is 46.8 cents error (or about half a semitone). The calculation quoted above is incorrect. Which it isn't you need to read the datasheet for the DAC in question to see the typical and maximum values for the nonlinearity. If you used a 7-bit DAC that would be one step per note (per 100 cents) - if the DAC was theoretically perfect. If you do 0-10 volt each step will be 4 cents (0.04 volt).Īn 8-bit DAC is clearly insufficient. Correct me if I'm wrong, but it seems that cheap 8-bit DACs aren't going to provide enough resolution for volt/oct use.ĭue to the way digital works an 8 bit DAC will only have 256 possible values. Deastman wrote:I've been endlessly frustrated in my attempts to find a suitable but affordable DAC.
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