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.

A digitally controlled attenuator chip contains not only a resistor ladder, but
also a heap of semiconductors to do the switching. I expect those who object to
them are wary of the SS junctions in, and perhaps also parallel to, the signal
path.

A motorised pot may be an expensive component, but it is easier to program the
control system. The pot remembers where it is, and only needs 2 bits to control.
OTOH, it is not convenient to use if you want a rotary control on your remote.

The main problems with all pots, motorised or otherwise is tracking over
a stereo pair. With 5.1 surround, there would have to be 6 tracking
controls so some form of electronic volume is almost essential.


I have never seen a remote with a rotary volume control. Why not? If the link is
reasonably error free, then it should be possible to put a rotary encoder on the
remote as well as on the system case. I hate push-button volume controls.


I don't think I've ever seen one either. The closest was a rotary
shuttle control for a S-VHS VTR which would allow frame by frame forward
or backwards movement. Now that I think about it a bit more, didn't QUAD
have one on their 66 and 77 series?

S.