Hum in Amp and Guitar?

[dumbassbob]

My 100 w. Marshall sounds great,but when I plug in I get this annoying hum,If I touch the back of the amp on any metal part,humm if I take my hands off of the strings,or I turn a light on -off, hummm. Could it be in the house wiring...Would a bad filter cap do this...what should I look for

[Chuck H]

It could be a loose or incorrectly located ground in the amp. The comment about on or off intrigues me though. Is this to say that there is increased hum AS you turn a light on or off? This makes me think there could be a grounding or polarity issue with your house wiring!!! I've played crappy bar shows where someone like "a friend of the bartender" replaced or repaired outlets on the stage and failed to get them all in the same polarity and hook up all the "third prong" grounds. You don't want to be without a spit guard on your mic in this situation.

What about other gear? Are you using anything else with the guitar or amp?

[dumbassbob]

My Marshall is a little hissy and hummy, My rack doesn't do it as much,but it has furman power filters.I think it might be the house wiring But what do I look for

[dumbassbob]

Hum in wall?

My Marshall is a little hissy and hummy, My rack doesn't do it as much,but it has furman power filters.I think it might be the house wiring But what do I look for

It is in the house curcuit Anyone know how I fix problem

[Jazz P Bass]

Call a certified electrician?

[Chuck H]

I think they sell polarity and ground esters at the many hardware stores. The first thing I would do is try your rig at another location and see if anything changes.

[dumbassbob]

I moved into bathroom plug, it was a little better.Sure is alot of humm in the line,I will get a wall checker tomorrow. I dont have the money for a electrician...Have any of you guys ever have this problem

[Chuck H]

The problem is usually pickup related noise from EMF's. Dimmers, flourescent lights, etc. But hum is another issue. If you have a signal generator perhaps you could do a listening comparison and tell us the frequency. 60Hz or 120Hz?

You never answered to whether the lights on/off thing is something that happens only while your switching the circuit or if it's a continuous hum after switching. You also didn't anwer to how the amp behaves with no guitar plugged in. This, assuming the input is a proper shorting jack.

[km6xz]

Is the sound hum or buzz? Is it restricted to very low frequencies or does it have a raspy mid and high frequency content?
You did not answer the question about the light switch, does the noise increase or decrease after turning on the lights. Does it matter where the light is located?
Without a better description of the noise, how to reproduce it and how to reduce it, anyone would just be guessing as to what the problem is.
Diagnosis first depends on evidence.

[norby3]

Is the sound hum or buzz? Is it restricted to very low frequencies or does it have a raspy mid and high frequency content?
You did not answer the question about the light switch, does the noise increase or decrease after turning on the lights. Does it matter where the light is located?
Without a better description of the noise, how to reproduce it and how to reduce it, anyone would just be guessing as to what the problem is.
Diagnosis first depends on evidence.

Try turning your body ninety degrees to either side, i.e. face East or West if you're looking North.

[DrGonz78]

Another question that I was wondering is did you just start to notice this recently or had a change or residence? I mean did you just ignore the hum for a while and then finally get bothered that now you are wanting to fix it? One word of advice to all is to not use coated strings and especially w/ tune-o-matic bridges. Recently, I had tested these coated strings for continuity and they had none at all until that coating was scraped off. Not saying that is what is going on here but thought it was funny trying to figure out why this guitar was humming so bad. Looked at all the ways that ground was made through the entire guitar and all that was left was the strings.

[Jag]

I never would have thoght of that!

[Chuck H]

The OP mentions that taking his hands off the strings has an effect. He also mentions that if he touches metal parts on the back of the amp it has an effect. So I'm inclined to think that there is continiuty through the guitar strings. Possibly too much ground is relying on the guitar itself and making ground loops? Bad peamp ground then? Or maybe the guitar cable or an effects cable shield is faulted at one end? So try a different guitar cord. Remove any effects from the situation. Isolate the problem as much as possible and develop a clear image of the problems manifestation and behavior.

[dumbassbob]

The problem is usually pickup related noise from EMF's. Dimmers, flourescent lights, etc. But hum is another issue. If you have a signal generator perhaps you could do a listening comparison and tell us the frequency. 60Hz or 120Hz?

You never answered to whether the lights on/off thing is something that happens only while your switching the circuit or if it's a continuous hum after switching. You also didn't anwer to how the amp behaves with no guitar plugged in. This, assuming the input is a proper shorting jack.

I just hear a noise in the amp when I turn the light on-off With just guitar into amp there is still noise,but not as bad until I turn on a OD then it is like a ocen in the amp When it is off you still here the hiss,Not hum,My rack gear is OK but you still hear the Seeeeeeeee.I live at the beach I just got a continnuity checker see if the plugs are messed up,The room was a remodel with a so called electrician It just the amp is so loud the noise it bugs the hell out of me Thanks for the input

[dumbassbob]

Is the sound hum or buzz? Is it restricted to very low frequencies or does it have a raspy mid and high frequency content?
You did not answer the question about the light switch, does the noise increase or decrease after turning on the lights. Does it matter where the light is located?
Without a better description of the noise, how to reproduce it and how to reduce it, anyone would just be guessing as to what the problem is.
Diagnosis first depends on evidence.

With the light on-off it is the same you just hear it like a little pop,Today It was ok until I used a OD pedal then I had the Ocean in the Amp,and only a lite hum when I took me hands off the guitar