pot static when attenuating a biased audio signal

[agent_sprinkles]

Hi guys! I'm having a simple problem I was hoping I could get another set of eyes on. I'm trying to put volume control i the biased part of my circuit - a super simple example is here:

http://imgur.com/BolZjh0

The circuit works, but any speed of pot movement beyond super-slow gives me a bunch of static on the signal as well. Any ideas what could be causing this, and how I can fix it, beyond just putting volume control beyond the blocking caps? If it matters, my bias voltage is 4.5V. Many thanks!

--Alex

[R.G.]

It's one of those truisms that any time you put DC across a pot and listen to what comes out of the wiper as you turn it, you will hear crackling. The pot wiper makes/loses contact with the resistive element as it moves. These are inaudible with only AC, but you will hear them with DC.

Put a BFC (Big Freaking Capacitor) in series with the hot side of your pot.

[psychedelicfish]

Put a BFC (Big Freaking Capacitor) in series with the hot side of your pot.

Either that, or put the pot between the 1uF cap and "out". You could also connect the grounded lug of the pot to your bias voltage instead of ground, provided you have a capacitor from your bias voltage to ground.

[R.G.]

... anything that keeps DC off the pot.

[agent_sprinkles]

thanks for the suggestions - Tying the ground lug to Vbias instead worked great!