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Let me first say, that I am no electrical engineer so thanks for taking the time to deal with a layman.

Background

In my workshop, I have two sets of speakers hooked up to a common 3.5mm audio source using a "Y" adapter.

One set of speakers is high on top of a shelf and for louder music when barbecuing or whatever. The second set is down low at the work bench level and is for listening while working at the work bench.

I have built a little panel with a couple of potentiometers that I can use as volume knobs to control the relative volume of each speaker set independently.

Problem

I wired everything up yesterday and all works as expected except that when I use the speakers together, turning one volume knob to zero kills the signal to both sets of speakers.

To be clear, turning just one knob does not lower the volume of the other set of speakers as it does it's own set of speakers, but when I turn the knob 100% to the "off" position, both sets of speakers go silent.

What am I missing here? I can't understand how in the world one knob would affect the other set of speakers at all.

Here is a crummy wiring diagram:

enter image description here

Thanks in advance.

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  • \$\begingroup\$ Resistor dividers don't care where the resistors are. \$\endgroup\$ – Ignacio Vazquez-Abrams Sep 13 '14 at 16:13
  • \$\begingroup\$ Your potentiometers kinda short circuit the signal lines if turned to the left. \$\endgroup\$ – Ghanima Sep 13 '14 at 16:17
  • \$\begingroup\$ Swap the reds that go to each pot. Are you meant to be running mono too? \$\endgroup\$ – Andy aka Sep 13 '14 at 16:39
  • \$\begingroup\$ Thanks Andy, I will try that. Yes, I ordered mono pots by mistake so just twisted left and right signal together before soldering. Just depicted in the diagram as a single wire for simplicity. \$\endgroup\$ – Matt Cashatt Sep 13 '14 at 17:52
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Yep, as @Andy aka noted, you want to swap your red lines. The result should look like this:

schematic

simulate this circuit – Schematic created using CircuitLab

Here is a pretty good resource: http://www.beavisaudio.com/techpages/Pots/ There is a section on volume control that reiterates the circuit above.

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The wiring of your potentiometers is probably wrong and therefor short-circuiting the signal when turned to the off-position. Please refer to Voltage Divider to correct your wiring.

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