"Nick Gorham" wrote in message

Arny Krueger wrote:
"Nick Gorham" wrote in message


Serge Auckland wrote:

Ian Iveson wrote:


The DSP solution would appear to be preferable.
However, presumably there are rounding errors. That
is, if I divide every word by a constant, each result
must be rounded to the nearest step, and this
rounding error is not linear wrt the audio signal. I
assume there is a name for this kind of error? How
significant is it?


The DSP solutions I'm familiar with operate either
floating point or 32 or 48 bit internal which means
that when the output is finally reduced to 16 or 24 bit the
errors from the DSP calculations are
minimised. I don't know of a specific name for the
errors resulting from DSP operation.


But even if the internal calculation is done with larger
resolution, you still loose one bit of output resolution
for every 6db of attenuation.


A very similar thing happens with analog level controls.
In the real world, even more so.

Yes, I guess so by definition, but I would hope a quality
pot or stepped attenuator should start with more than
96db worth of resolution.

You seem to forget that pots and stepped attenuators are generally attached
to power amps and preamps. Power amps can have from 80 to 115 dB dynamic
range , butwith consumer amps crowded more toward the lower end of the
range. Most home audio preamps have only 70 to 90 dB dynamic range,
depdening on the input.