DAC "error"

[Rene Schmitz]

Hi all!

I'm wondering why most people get away with 8bit DACs (or even discrete
7bit DACs like myself). I think that if you play C 3 which is 60 decimal,
the maximum relative error would be 60/60.25=99.58% (i.e. 1/4LSB error
assumed).
This is less than 0.5% error, still audible if you beat against a
"perfectly" tuned instrument. Of course the error gets bigger the lower you
get, you'll get 25% maximum relative error when you play Db 0. 

Bye
 René

At 00:26 14.01.00 -0800, Chris MacDonald wrote:
>Paul Schreiber wrote:
>> Amen, brother! But if 1LSB *is a step*, then 1/4LSB is 25% error! You need
>> 1/100th LSB.
>
>Although you might disapprove I should say that I have worked up a
>MIDI/CV converter with an 8 bit DAC (DAC0808LCN) where 1 bit was half a
>step.  Now I realize this device is no match for a Kenton and that with
>a maximum error spec of 1/2 LSB there is a possibility of up to +/- 25
>cents error from a semitone.  But my goal was lowest possible cost (even
>$10 each is not cheap in this application) not superior performance, and
>as it turns out I haven't found a specimen so far that has exhibited
>unacceptably high error.  If someone can point me to a readily available
>12 bit DAC for around $1.29 though that would be great!
>

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