Should tone controls remove ALL the tone?

[DarkPenguin]

I've just put some alpha pots in my guitar as tone controls.  I expect that when I turn the volume all the way down that it should mute the guitar.  I wouldn't expect that from the tone controls.  Is this how they work or did I miswire something?

 

[Cagey]

You've mis-wired something, or perhaps your capacitor is much too large.

 

[croquet hoop]

Check your ground connections around the tone pot.

 

[Tony Raven]

Yeah, you've just added more volume controls.

The typical tone pot uses a capacitor to "scrape off" tones above a certain frequency (determined by value in microFarads). If you're scraping off 100%, then you've missed the cap entirely.

 

[DarkPenguin]

I wonder if I fried the cap....

 

[DavyDave53]

The voltages in a guitar are not going to fry anything.

If the cap is bad it probably came that way.

What are the caps values?  (Published and measured)

 

[DarkPenguin]

I was thinking fried with a soldering iron.  Baked more than fried.

0.22, I believe.  I'm sure I have a meter of some sort around the house.  Haven't found it.

 

[croquet hoop]

Yep, the heat of a soldering iron can fry pretty much anything, especially if you heat the thing more than a few seconds.

 

[line6man]

I was thinking fried with a soldering iron.  Baked more than fried.

0.22, I believe.  I'm sure I have a meter of some sort around the house.  Haven't found it.

That's your problem. 0.22(uF, I'm assuming) is an order of magnitude too capacitive for the average signal impedance in a passive instrument, and even a bit high for lower impedance active circuits. The result is a very low frequency cutoff point, basically allowing the pot to vary output impedance over all frequencies.

 

[DarkPenguin]

For the love of...  I don't want to admit this but what I did was wire the capacitor into the wrong spot.  Then when I bent it down to tidy it I completely masked how it was wired.  In other words it looked right but actually wasn't.

This was a 10 second job for a multi meter.  I really need to find that...

Thanks for everyone's help!

 

[Jumble Jumble]

People always misreport their capacitor values, don't worry about it. If someone says 0.22uF, chances are they mean 0.022uF. Especially if they buy their stuff from a guitar parts company rather than a Radio Shack equivalent.

I asked an artist's guitar tech what value he uses for the tone controls in the guitars, and he said "I'm pretty sure it's... point-twenty-two picofarads".

I'm pretty sure it's not - that's 0.00000022uF. They're quite hard to come by, I don't think turning the control would make an audible difference (certainly not a useful one).

 

[DarkPenguin]

People always misreport their capacitor values, don't worry about it. If someone says 0.22uF, chances are they mean 0.022uF. Especially if they buy their stuff from a guitar parts company rather than a Radio Shack equivalent.

I asked an artist's guitar tech what value he uses for the tone controls in the guitars, and he said "I'm pretty sure it's... point-twenty-two picofarads".

I'm pretty sure it's not - that's 0.00000022uF. They're quite hard to come by, I don't think turning the control would make an audible difference (certainly not a useful one).

It was for guitar so I'm guessing you're right.  Wired properly it works as expected.