I have a Audio-Taper Potentiometer that I bought from RadioShack and would like to hook it up in-line to my sub woofer so my 5.1 surround sound's bass is not so loud. However, the connections from the sub to the main receiver are proprietary plug on the back of receiver so I can't tell which is positive or negative. Does this matter for hooking up a Potentiometer? Where can I find a wiring diagram?

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    \$\begingroup\$ You need to understand a lot more about this situation - it seems you have bought a normal potentiometer (albeit with "audio taper", probably just meaning "logarithmic resistance scale"), which is for small signals. Your subwoofer connection, however, is most likely a LARGE (power) signal. The two cannot just be hooked up. \$\endgroup\$ – John U Feb 28 '13 at 17:42
  • \$\begingroup\$ Datasheet? Specifications? I give you benefit of the doubt, but I wouldn't be surprised if @JohnU is right that the part is intended voor small signal, not power output stage levels. \$\endgroup\$ – jippie Feb 28 '13 at 22:42
  • \$\begingroup\$ I just googled "radio shack audio taper potentiometer" and a load of standard pots came up, nothing that looked like it could dump multi-watts, and frankly if there is such a product it's dumber than the USB heated slippers my boss bought me for Christmas. \$\endgroup\$ – John U Mar 1 '13 at 8:42

Some audio taper potentiometer that you bought at Radio Shack is unlikely to be useful the way you imagine unless this "subwoofer" is really a lot more than just a subwoofer. The impedance of the signal that drives a speaker, like a subwoofer, is very low, well under 8 Ω assuming a 8 Ω speaker. Pots for volume control are much higher impedance, and can't handle that kind of power level anyway.

If this "subwoofer" really isn't, and actually contains a amplifier, then the pot might do what you want. You can tell this case several ways. If there are only two wires going to this unit coming straight from a power amp, then the pot won't work. For the pot to have any chance of doing what you want there has to be separate power, like a line cord, connected to this box. In that case the signal could be "line level" and is amplified as needed by the speaker inside the box.

If you have the latter case, then it should be pretty easy to figure out which wires are what. Turn on the unit and put your finger on each line. When you touch the audio line, the hum picked up by your body should be amplified and audible in the speaker. Touching the ground line won't have that effect, and might even make any slight hum coming from the speaker weaker. Connect the ground wires as usual, but break the audio wire connection. Connect one end of the pot to the common ground, the other end to the audio line coming from the preamp, and the wiper to the audio line going into the speaker box.

Can't you just turn down the bass at the preamp so all this isn't needed?

  • \$\begingroup\$ I think Radio Shack sold (and perhaps still does) some "volume control" assemblies that were designed to adjust the volume of 8-ohm speakers; it looked like the assemblies had some sort of transformer on them. I would guess the idea was that if one wires a low-voltage side of a transformer in series with a speaker and the high-voltage side to a rheostat, one may usefully employ a higher-resistance rheostat than could be wired directly in series with a speaker, but I think that was designed for lower power levels than would be typical of today's subwoofers. \$\endgroup\$ – supercat Feb 28 '13 at 19:35

If it is colored then most of the time the balck one is ground and red is the hot one.

If not colored then go ahead and try. You have 50% for success for first try and 100% for the second :-)

  • \$\begingroup\$ If I hook it up backwards, will it fry the stereo or damage it? \$\endgroup\$ – captainandcoke Feb 28 '13 at 17:12
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    \$\begingroup\$ Speaker wires are often differential drive, treating either as "ground" is a poor idea. \$\endgroup\$ – John U Feb 28 '13 at 17:39
  • \$\begingroup\$ The real danger is in wrongly connecting the potentiometer and shorting out the amplifier output. Colors come in many kinds, my cables are white and green for example. Whether the output is differential or not is not an issue here. Anyway without a spec sheet for the part we know too little, but it is probably spec'd for small signal and not output driver levels. \$\endgroup\$ – jippie Feb 28 '13 at 22:39

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