CDP volume, what's best, analogue or digital?

Ed_sawyer...On further thought...a one bit shift (multiply by 1/2) would be a 6 dB volume reduction, and I don't think that digital volume controls are that coarse. The volume control on my Rotel 1066 SS processor is probably digital, and it goes in 1 dB steps. So there must be something a little more sophisticated than loosing a bit.

Ed_sawyer...Thanks for the info. Dropping the LSB is how you multiply by 1/2, in context of my comment. For further gain reduction I suppose they do more shifts (dropping more bits). Perhaps they figure that as the volume level goes down you don't need 16 bits, 15 bits, 14 bits, etc. as the LSB is not audible anyway. However, I would not design it that way.

One idea that someone could use to mitigate the evils of digital gain control would be to add a very simple (cheap) 4 or 5 step analog attenuatior between the digitally controlled source and the power amp. This would be used like a "range" switch, to select the approximate volume desired, and then the digital control could be used to make only fine adjustment. The analog range selector would, for one thing, take care of the attenuation that is always necessary simply to cut the preamp signal down to match the power amp sensitivity. (Preamp designers always put out more volts than necessary to be sure that their product will work with any power amp). Of course, this "range selection" approach would also be suitable for automatic digital control.

Thank you all. I'm sure it was discussed before but my searches only come up with separate discussions and not pros and cons of both volume controls in one thread. Analogue seems to be the best way to go, but are the likes of Wadia doing so wrong with their digital volume?

nuno

Wadia, et al - basically they just drop the least significant bit(s) to attenuate the signal = hence degradation.

The concepts postulated by eldardfort are good ideas, but likely more work/effort to implement vs. a decent analog attenuator/vol. pot.

I've had good luck with the Sony XA7ES - their top of the line CD player from a few years ago. I had a remote-controlled analog volume control output, in addition to fixed-level outputs. very handy. The vol. control also works on the headphone output.

-Ed

Tireguy...I say again: how, in detail, is volume control mechanized "in the digital domain". The only way I can think of would be to multiply of each 16 bit audio data value by the selected gain (attenuation factor) prior to D/A conversion. That would waste the high order bits of the D/A converter, and degrade resolutiuon. It would be easier and better to digitally select a tap on a resistor ladder, which is equivalent to using a stepped attenuator instead of a pot. Digital replaces your hand turning the pot, but the signal processing remains analog.

For things like this it would be nice if Audiogon had a way to include a diagram in a post.

My cost effective recommendation for CD only system is to use analog output from your CD player or DAC directly into analog EVS Ultimate Attenuators fitted directly onto the amplifier RCA input jacks eliminating any extra interconnect between a passive preamp and amp. Tweakaudio.com customizes these for either transistor or tube amp. As stepped attenuators there is not the very fine adjustment of a continuous analog volume control, but transparency and dynamics are so outstanding that the retail list price of $350 is a bargain.

Eldartford- I think he is refering to digital being the likes of Accuphase, Wadia, etc which everyone knows the volume control is done in the digital domain. As were units from the likes of Audio Aero, Resolution Audio, Cary use a volume control employed in the analog domain.

All of that being said I wouldn't even think about getting a player with digital volume control, having owned both there is no comparison- do you want to hear everything on the recording or not?? its really that simple. I am not saying that they won't ever get digital volume perfected but at this time it does not exist.

This has been discussed at length, both here and at Audio Asylum. Do a search for more info.

Conventional wisdom is that digital volume controls affect performance, and that analog volume controls are best if going direct to amp.

Another option is to get a passive preamp with transformer volume control such Bent Audio, Placette, Consonance Django (and several others).

You need to define exactly what is meant by a "digital" volume control. Various mechanizations of volume control are possible where the volume level is digitally selected, but the signal processing remains purely analog.