dual gang pot - what's the extra lug for?

[amonte]

I got a dual gang pot at RS to try a little experiment on a simple pedal design I've got on my breadboard.  I wanted to use the old input cap blend trick on both the input cap of the circuit and the bypass cap off a transistor - the idea being that I can "even out" the increase/decrease in bass while changing the bypass cap value by decreasing and increasing the input cap value.  Haven't tried this yet, but I noticed the pot that I have has an extra lug (two, actually since it's a dual gang pot).  What is this lug for?

[Peter Snow]

The extra lugs are probably centre taps whereby a connection can be made half way round the pots' rotation. I have seen single gang pots with centre taps used as balance controls on stereo pre-amps.   If you don't need the centre taps just ignore them.

Cheers,

Peter

[Paul Perry (Frostwave)]

If they ARE centre taps, I can use them! but, they may not be connected at all, just there for extra stability if they are PCB mount. Get onto them wiht the multimeter, that's the only way to know for sure.

[Processaurus]

Could be connected to the pot shell for grounding purposes.

[Mark Hammer]

Nah.  They're taps that are used for loudness compensation when such pots are used as stereo volume controls.  Just like compensated volume pots on guitars, and bright switches on amps, stereo volume pots can have compensation added to them so that as the overall volume level is decreased portions of the bass and treble are not decreased quite as much.  This is (hopefully) done according to the classic Fletcher-Munsen equal loudness curves to compensate for the quirks in the human hearing system.  Typically, as volume level drops beyond a certain point, sensitivity to sounds in the range of the human voice are retained, but sensitivity to sounds outside that range (deeper bass, upper treble) diminishes.