Scratchy Tone Pot

[mrichman]

My newly aquired Anderson '02 Hollow T has developed a nasty scratching sound when the tone pot is turned. It seems to be some sort of ground issue since it doesn't scratch when I touch the strings at the same time. Does anybody know what I can do to rectify this? The volume pot is fine...

[bruce]

This is normal....It will make noise if not grounded, (touching the strings).

[bruce]

OOps...What I meant was... touch the strings to ground the guitar and the noise will go away.

[morty]

I have a Drop Top. and it also makes a bit noise when I don`t touch the strings.. I tought It was because the last owner had switched from his duncan to the original TA pickup. and had some bad wireing, ut I guess all guitars has this problem or????

[mrichman]

Well, both my Anderson Drop Tops and my Cobra don't have this problem so how is it "normal"? Also, if that were the case, wouldn't the volume pot also have the same noise?

[dpeterson]

oh no... roys most dreaded phone call question... :)

dave

[morty]

I think I was answering wrong question.. It`s no sound from the pot.. These sound is just dirt in the potmeter i think.. I am talking about sound when you are not touching the strings.. this is spesially notised when you turn down the stage light.. so I guess it`s a ground problem.. It`s the same on my Fender too.

[tom]

here's the long answer. in an effort to make really smooth feeling pots, the manufacturers use a non conductive lube on the shaft to bushing connection. this makes for an intermittent connection between the two metal pieces. if you are not touching any other metal parts on the guitar, you are intermittently getting connected to ground. i can't think of a real playing situation where you would not have either your left hand on the strings, or your right hand on the bridge, so i think the better feeling pot is a good compromise. i'll make another post to explain about string ground.

[tom]

My guitar is making a lot of noise that subsides when I touch either the volume or tone controls. What’s the problem?

The problem you're experiencing is a common one that has a rather complex answer. First of all, any guitar that
doesn't have active pickups will have this problem. The problem is that we humans are very good conductors of electricity, being sacks of mostly water. You're guitar is grounded through the guitar cord to your amp. You, are also grounded when you are touching anything metal on your guitar. You being a great conductor, acting as a shield when you are grounded. This is why when you are near your amp, and holding your guitar, you can turn your body to reduce the hum coming from your amp. When you are not grounded to your guitar (not touching anything metal), you are still a good conductor, but instead of being a shield you are an antenna for all the world's hum and noise, drawing it close for your guitar to hear and amplify. The most common solution for the problem is to roll your guitar volume pot down when you are not playing or keep your hands touching some metal on your guitar.

[bruce]

Originally posted by mrichman
Well, both my Anderson Drop Tops and my Cobra don't have this problem so how is it "normal"? Also, if that were the case, wouldn't the volume pot also have the same noise?

Both of your Drop Tops and Cobra most likely have different tone pots than the one in question.... so yours are normal too. We've tried many different pot manufactures over the years as Tom has said and some push/pull tone pots make "the noise" when not touching any metal on the guitar. And, no, the volume pot doesn't make "the noise" since it is a different pot all together.

[Roy (maybe)]

Hi

As Tom said earlier, a lot of it has to do with the type and amount of lube used by the pot manufacture. The lube is and insulator and when the pot is rotated it can keep the shaft from being grounded momentarily. If you had plastic knobs this would not be a factor because you could never use the knobs for grounding. This is not a flaw, just a characteristic. Some guys like to spray contact cleaner in their pots in hopes of washing out some of the thicker lube in favor of the thinner contact cleaner lube. Not really necessary. Read on first before spraying.

Keep in mind that the biggest factor is environment. If you are in a “quiet” space the guitar won’t make much noise under any condition and if you are in an electronically noisy place the guitar will hear it until you touch some positive ground and the extemporaneous noise is harmlessly shunted to ground. This is why all electric guitar manufactures ground their strings. Hold onto the strings when you play or are plugged in and idling.

In my experience, normal playing technique should include rolling the volume control off in every non-playing situation—for any guitar made by any manufacture. For illustration, and fun, I think of it the same way as I think about riding a bike or a motorcycle. When I roll up to a stop sign I put my foot down or I will tip over. With an electric guitar I roll off the volume when I finish a song or I will have unwanted noise. It all happens automatically for me now.

I hope that helps a bit.

Happy Playing,
Roy (maybe)

[mrichman]

Thanks for everybody's answers - of course, I know about the whole grounding issues, fingers on strings when you're not playing, etc but in this particular case, I've never had that same scratching sound when the pot is rotated. As I've mentioned, I've got 4 other Andersons that don't do this, including 1 other (Cobra) with, I assume, the same pull/push tone pot, so I didn't think it was normal. It's not bothersome enough to affect real world situations but it is annoying enough to consider using pots that don't have this characteristic. Is it unique to the push/pull pots that you use?

[bruce]

Originally posted by mrichman
Thanks for everybody's answers - of course, I know about the whole grounding issues, fingers on strings when you're not playing, etc but in this particular case, I've never had that same scratching sound when the pot is rotated. As I've mentioned, I've got 4 other Andersons that don't do this, including 1 other (Cobra) with, I assume, the same pull/push tone pot, so I didn't think it was normal. It's not bothersome enough to affect real world situations but it is annoying enough to consider using pots that don't have this characteristic. Is it unique to the push/pull pots that you use?

Yes.

[Roy (maybe)]

Hi mrichman,

Have you tried spraying to change the conductivity of the lube inside the pot?

Have fun!

Roy (maybe)