Reply To: Debunking the Digital Audio Myth: The Truth About the ‘Stair-Step’ Effect

June 4, 2023 at 9:29 pm #5838

There are a few issues.  One is that virtually all of the modern audio DACs are ΣΔ meaning virtually none of the modern audio DACs are what we call “conventional DACs”.  A conventional DAC would have a staircase output at the audio sample rate, but the output of that would also be low-pass filtered with an analog filter, which would smooth out the edges of the staircase output.

ΣΔ DACs also have a piecewise-constant output, but at a much higher sample rate.  So you would have to zoom in to about 3 MHz to see it.  And it wouldn’t be much of a staircase because the ΣΔ DACs toggle between +1 and -1, none of the values in between.  And they get analog low-pass filtering, too, which smooths things out.

But if you were running a conventional DAC at reasonably slow sample rates, you would see that staircase function if the sine wave frequency was fast enough.