Popping in stepped volume control

[trombone]

I have a stepped volume control on a tube preamp. It is a series resistor design. Lately, when I turn it, it emits a fairly soft pop. Also, when I tap on the preamp, I'll sometimes get a sputter. I think the cause might be a tube (replaced one), but I seem to remember this being a longer standing problem on and off than the life of a tube. Obviously, I could simply resolder every joint, but I wonder if there is any particular place I should look. If not, I'll do more tube swapping and soldering.

[Minion]

I seem to remember with Stepped attenuators that you need to get the "Make Before Break" type of stepped switch to aviod pops ..... I don"t know if this is your issue .....

[trombone]

I don't think so. These are pretty good pots, and the problem is only one side.

[Frank Berry]

You may have a bad coupling capacitor on the input or output side of your stepped volume control. A little DC leakage through the capacitor can cause this problem.

[DavesNotHere]

I had that problem when I reused some tube sockets one time.

swap the attenuators from left channel to right channel. if the problem follows, repair the attenuator, otherwise its most likely a tube socket or bad solder joint on grid stop resistor (if it has one)

[janneman]

Originally Posted by Frank Berry

You may have a bad coupling capacitor on the input or output side of your stepped volume control. A little DC leakage through the capacitor can cause this problem.

That's the most likely cause. If you have some DC on the pot line(s), switching that pot will cause a DC step which will he heard as a tick or pop.

jan didden