Why are amplifiers "mute" at 2 volume positions???

[birb]

i have an old stereo from 1977 where the first 2 notches on the volume dont output an amplified signal and are basically just muted, the gain controls on my PA amplifier do the same thing, the lowest 2 notches are basically muted. i understand why the lowest would be mute but why also the second notch???

 

[sergeauckland]

Sound to me that the volume control is worn out, and the track doesn't make contact any more with the wiper. No volume control works like that by design. The bottom of the track should be a short circuit to ground, so muted, but once off the bottom stop, there should be signal.

Occasionally, and mostly with electronic volume controls, the bottom stop isn't muted, just very attenuated (say -60dB), but again the next to bottom position should have signal on it. There's no point in two muted positions.

S.

 

[birb]

Sound to me that the volume control is worn out, and the track doesn't make contact any more with the wiper. No volume control works like that by design. The bottom of the track should be a short circuit to ground, so muted, but once off the bottom stop, there should be signal.

Occasionally, and mostly with electronic volume controls, the bottom stop isn't muted, just very attenuated (say -60dB), but again the next to bottom position should have signal on it. There's no point in two muted positions.

S.

i have this behavior on every single amp i have owned, even my brand new QSC amplifier does the exact same thing. -inf has no amplified output which makes sense but the second notch does essentially the same thing, no amplified signal.

 

[birb]

it's for different sensitivity speakers - if you were to try some 16-ohm speakers you'd likely hear something on the notch that's quiet with your current speakers.

the output volume of the signal is there at -inf as i can still very faintly hear an output, the next notch up behaves exactly the same, no increase in volume

 

[Redacted]

is it the same when you plug headphones in? (if there is a socket)

The QSD probably has rotary encoders, not pots, so it's possibly mapped in software.
You can always put a cheap (£25) oscilloscope on the output and see what happens between 0 & 1 as it were, with a test signal. It's possible you just can't hear a difference in output, or, a PA amp may have a noise gate.

 

[birb]

"Because those knobs are usually rotary encoders or stepped attenuators with a detent at minimum, not magic “more silent than silent” settings. Common reasons: - The first click is the mechanical stop/min setting - The next detent may still map to 0 or mute in the control logic - Some designs leave a couple steps at zero for tolerance, channel balance, or a clean mute region near the bottom - On cheap gear, the labeling/step mapping is just wonky because apparently chaos was cheaper So yeah: not two different kinds of silence, just how the control is implemented." -Bark AI bot that can be found on libera.chat

would this be accurate?
the QSC is designed for PA use etc. so it would make sense for tolerance