What is the optimal dB distribution for a volume control?

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#3
Wikipedia
Most (cheaper) "log" potentiometers are not accurately logarithmic, but use two regions of different resistance (but constant resistivity) to approximate a logarithmic law. The two resistive tracks overlap at approximately 50% of the potentiometer rotation; this gives a stepwise logarithmic taper.[5] A logarithmic potentiometer can also be simulated (not very accurately) with a linear one and an external resistor. True logarithmic potentiometers are significantly more expensive.

Logarithmic taper potentiometers are often used for volume or signal level in audio systems, as human perception of audio volume is logarithmic, according to the Weber–Fechner law.
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You could argue that the center position should be half the dynamic range of your system, but realistically it should be a comfortable listening level. At some point the task of setting levels needs to be split between the volume control and adapting the input levels of different sources. I had assumed that the center of most pots was 10% (-20dB), but that is probably a poor estimate. The center of the volume control should not be so far below 100% that the following gain makes the noise floor audible, ie -30dB would be pushing it, and the reason the volume control is usually on the pre-amp output and not earlier in the chain. The business of gain structure is a bit of an art that many fail.
 
#4
In fact, a lot depends on the gain structure and level. But I want to point out something different: Is a range from -60dB (0% pos.) to e.g. -30dB (50% pos) not very far because only a few dB per angle are exceeded. ALPS potentiometers are around -15dB at pos 50%.
 
#5
FWIW, and IMO only, a volume "knob" (since you mentioned 12 o'clock) feels best when it is allowed turn from about 7 o'clock to about 3 or 4 o'clock only. This puts the volume at 12 o'clock closer to the maximum than the midpoint.

Also, 60dB is a lot of range. Even 40dB is plenty unless the system has some huge dynamic range capability or something. If you want the extra 20dB that you get with a 60dB range, I would make the step sizes below -30dB from larger, e.g. 2-3 dB or even more at near the minimum. Otherwise there are just too many positions to sweep through, and more is not better. With only the fingers (thumb and the first two fingers) you can easily and quickly rotate a knob about 150 degrees, and so within that range should be most of the normal volume settings, which is probably from the minimum volume up to -15dB or so. Then the final 15dB can be covered in small steps of 1 dB or 1.5 dB and that requires rotating the arm, which takes more effort. This might protect an accidental rotation "all the way" up to 11...
 
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#6
Perhaps I am a cheapskate, but when I went to a stepped attenuator I just noted the 4 volume settings positions I used on my volume pot (normal quiet listening, normal listening, loud playing guitar, and full volume) and replicated them on a 5 position switch. It works a dream. I really don’t need 1.5db accuracy.
Happy Friday y’all
 
#7
Sure, but your settings might be totally wrong for the next guy with speakers of a different sensitivity level, amplifier(s) with different gain level(s), etc. Also, recordings come with varying average signal level and adjusting for this requires a finer adjustment than only 5 level possibilities. So for a DIYer build I could see how this might work out just fine, but in general not.
 
#8
True, and I will have to change the R values when I move the system to a different room, but I kind of like the ease of use. I have a hundred volume setting values on the TV and find that I will only use even numbers, or prime numbers etc. 4 is so much easier.
Keep well
 
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