"Jim Lesurf" wrote in message
...
In article , Keith G
wrote:




As Don Pearce mentioned, the provision of a "digital" volume control
is often done for reasons of cost. Digital volume controls track left
and right channels virtually perfectly (comfortably within 0.1dB)
from full output to extremely quiet, and don't generate any
significant noise when changing levels. Normal carbon pots can be
relatively quite noisy, and even conductive plastic pots will find it
difficult to track both channels to better than 2dB at high
attenuations.


Interesting.

FWIW some of the larger and more expensive 'pots' are stepped attenuators
with laser-trimmed resistances. One of the benefits of these can be much
closer tracking of the balance as you wind down the level. They may also
use 'landings' between the settings that are particularly good at not
deteriorating with age/use. However they have tended to cost far more than
simple pots...


Excellent answer Serge - thanks. Makes me think there's even less of a
good reason for manufacturers to avoid them if, as Don says, they are
'properly implemented...???

The problem is that the 'proper implimentation' involves processes which
the user can't directly check, and the makers may be lazy or trying to cut
corners...

I would have thought a standalone 'digital attenuator' (with remote?)
would be a good thing for some valve amp owners - I wonder if such a
thing is available??

The concerns may be:

1: such a unit would require its own power and ADC/DAC, buffers, etc.

2: Would valve/analog enthusiasts wish to have this digital/solidstate
device always in their signal chain? I'd have thought they'd fear it would
corrupt the 'purity' of their system. :-)

3: Good quality stepped attenuators and detented pots exist and can work
fine.

FWIW I have always used the ALP 40mm stepped detent volume controls. When
I bought them commercially in the past I got them with tight levels of
balance, etc, spec. If you can find a source for these, I'd recommend you
try them. You may find they give an active attenuator a run for its money.



That's all very interesting but a little way wide of the point - forget
expensive, 'laser cut' options, my curiosity here is that in an amp costing
only 60 quid (and which includes 6 inputs, headphone socket, phono stage as
well as all the necessary ADC/DAC circuitry, power supply &c.) there is a
very useful *digital* (ie cheap) way of controlling
volume/treble/bass/balance/muting/'loudness' with some of the major
functions (not all) available on the (included) remote control.

I reckon this could be of interest to some (if not many) valve amp users,
as none of these functions are normally available outside of arm's length
with valve amps and some are not usually available at all! I know there are
times when I wouldn't mind being able to make various adjustments without
having to get up - volume being the obvious choice, but being able to zap to
a tuner after a record has finished (and the deck switched itself off) and
then change stations (when the volume control would be *essential*) would be
neat!!

If 'properly implemented' means that any artifacts, digital 'rounding off'
or whatever are *inaudible* there might be the possibility of an inexpensive
digital 'front end' which offers the convenience of remote control on the
main functions as well the additional capability to adjust
tone/balance/loudness/muting &c. (An amusing concept on a valve amp!!)

Or, as the price of the whole amp is peanuts, I would even go as far as to
suggest that someone with more expertise than me could butcher one of these
amps to create a very interesting 'digital pre' with all the afore-mentioned
functionality!

;-)