Hum in amp from guitar

[ronh]

My amp hums when I have my guitar plugged into it. You know the kind of hum that goes down in level when you turn your guitar a certain direction in the room. The input jack is a shorting one and with nothing plugged in there is no hum. I dont have this problem when I plug this guitar into another amp.
Anyone know the cause and the solution to this? Thanks in advance for any help.

[Bruce / Mission Amps]

My amp hums when I have my guitar plugged into it. You know the kind of hum that goes down in level when you turn your guitar a certain direction in the room. The input jack is a shorting one and with nothing plugged in there is no hum. I dont have this problem when I plug this guitar into another amp.
Anyone know the cause and the solution to this? Thanks in advance for any help.

I bet it is still the guitar but some amp's transformers are not very well shielded and the pickups will "hear" the darn things and send it right back to the very same amp's preamp stages. Single coil wound pickups are the worse of course.
Really good shielding will help as far as the guitar goes and maybe a change to the amps transformers will do it too.

[Enzo]

Get your longest cord and use it. AIm the guitar for the most hum. Now back straight away from the amp. Does the hum reduce the father away you are? If it does, then you probably have what Bruce described.

If it doesn;t much matter how far from the amp you are, but does matter which direction you face, then it is the guitar picking up the local electrical environment.

[loudthud]

Do both amps have three wire power cords with no damage? If you put the two amps next to each other does the hum come and go when the bad amp is turned on/off even though you are plugged into the good amp?

[GregS]

It could be the room you're in. My amps do exactly what you describe where I practice but are fine anywhere else. I happen to be directly under a flourescent light where I practice which probably has something to do with it.

[ronh]

its in the air tonight

I think Enzo is right. 20ft from the amp, the hum is there, but turning a different direction reduces it. Also, very strange. My tuner is always showing me a flat 7B note with or without a guitar plugged into it. I checked all the outlets in the house with one of those AC wiring testers. All outlets passed. This can't be good for my health. Thanks to everyone who answered.

[daz]

Being that it could be any number of things, chances my or anyone else is going to nail it for you is low. But i just had the same problem driving me nuts for a couple days till i shot some deoxit into the pots. nothing happened till i hit the master volume and the hum instantly stopped ! So to at least eliminate that possibility you may wanna clean your pots. Always a good thing anyways whether or not it works.

[Gaz]

nothing happened till i hit the master volume and the hum instantly stopped !

Can you explain this again? Thanks.

[Jazz P Bass]

Cleaning potentiometers

I believe the last post indicated that using Caig Deoxit D5 helped clean the master pot.
Spray a little in the slot where the three tabs are & rotate the pot back & forth. Key word: a "little". You don't want to soak it.
Here is a link:DeoxIT D5 Spray Contact Cleaner, 5% solution, 5 oz. | Caig Laboratories | D5S-6 (D5S6)

[daz]

Yep, and don't try and figure it out because i know it sounds odd. But it's true. i didn't even have to rotate it. The second i shot it in the hum just stopped. Never saw that before but i assure you it happened. Makes you realize it's important to give them a shot now and again.