Volume Controls - Can they affect Dynamic Range?


These days it’s possible to turn up the volume via several components in the signal path. For instance, I often connect my iPad to my Apple T.V. (then optically to my DAC.) I can turn up the volume via my iPad or via my Pre-amp. I think I’m getting better dynamics when I leave my iPad set to the lowest level and use my Pre-amp (Cary SLP-05) to adjust the volume. My system is: https://systems.audiogon.com/systems/5893. I do have one confession to make though: I’m not using the Chord DAC I’m using a first gen Cambridge audio because it drives my balanced outputs better. The newest Cambridge DAC also has a volume control (as does the newest Apple T.V.) - presenting some users with even more places to crank it up. What are your thoughts on this?
thegoldengoose
Most volume control work by attenuating (reducing) the volume from a full signal. So best sound usually comes from leaving the crappier volume controls unattentuated aka full volume up, and using the best volume control (almost always an active -- or sometimes a passive --preamp). Be careful to first turn the preamp volume down to zero before you turn the others up! Cheers,
Spencer
"These amplifiers go to eleven...."

The answer is complicated. It depends on gain, noise, overload and resolution. Your ears are your best guide when things get complicated.

For digital to digital, I leave everything at max, and let my preamp deal with volume. The Mytek DAC I use has an analog volume control I only use for the headphones.

However, say the Oppo players. You can set the volume of any speaker from several DB above, to below unity (input = output). The problem is, and they acknowledge it, setting the speaker levels above unity causes digital distortion because you need more bits than the players have. This is also a problem for upsampling players. If you upsample a 24 bit master, you may end up creating samples louder than 24 bits will allow. Benchmark media has a blog about this.

Digital volume controls can be from crappy to decent. The problem is they all involve a lot of math, so you loose the bit-perfection of the original signal as soon as you apply any sort of multiplication or division. This is a big problem with computer sound, and why so much discussion is around avoiding the normal audio mixers built into the OS.

Some of the best digital volume controls however use 32 bit DAC’s to compensate for the loss of resolution you would have otherwise.

In the analog domain, your issues are things like channel matching, overload and noise. Any analog output has a limited power supply, which defines the maximum voltage swing. Most preamps also have a lot more gain available than you'll ever need. The more gain, the more noise. Turn the volume up and you'll run out of voltage, causing clipping. Poor volume controls cause imbalance in L to R matching, and the wipers they use can get dirty. 
Thanks for your comments.  Interesting comments on the 24/32 bit stuff.

Do you know if the software attenuates the same way a piece of hardware would?

Software volume is the same as digital volume controls.


So, yes.

Erik