I've come across a way to connect a regular pot to be used as a volume or gain pot, but the input and output terminals are reversed. It seems that this way of using it is somewhat common in the electric guitar realm, as I haven't found any other info or mentions elsewhere. The idea behind it is that if you have more than one signal source, each with its own volume control, by muting one of them by turning the pot all the way down, the rest won't be silenced as well because the signal won't be shorted to ground. Here's how it would be used as a volume control for a guitar pickup (voltage signal source):

enter image description here

And here, a dual gang pot is used in the same way to mix dry and wet signals in a tube guitar amplifier's effects loop by simply turning up the volume of signal B (signal coming out of the first triode's cathode) while simultaneously turning down the volume of signal A (signal coming from whatever is connected to the second jack) and vice versa, the "mixer's" output is the top of the pots which then go to the grid of the second triode. The 10k resistors are to avoid shorting the outputs of the signal sources when each pot is turned all the way down.

enter image description here

I haven't actually tried this but I know this has been used for decades now so, my question is how or why would this work and most importantly, how do you simulate this in say Proteus or LTspice? I've tried simulating this circuit using pots or resistors and the result is no voltage loss whatsoever

  • \$\begingroup\$ I don't have any advice on the analysis, so I'm not posting an answer, but an important practical issue is that this shorts the input to ground when it is at zero. That's fine for a guitar pickup but not when the signal source can't tolerate a short (or if it is being distributed elsewhere on the same wire). You can sometimes see this effect in practice by using a passive attenuator box with its input and output jacks reversed. \$\endgroup\$ – Kevin Reid May 6 '20 at 2:35
  • \$\begingroup\$ Yes, that is a definite drawback, however it can be avoided by connecting a small resistance in series with the source, that resistance will still be seen by the source even if the pot is turned all the way down, the trade off is that that very same resistance will form a conventional voltage divider with the pot when it is turned all the way up, that's what the 10k resistors are doing in the 2nd image :) \$\endgroup\$ – Raz May 6 '20 at 2:49

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