Need advice, P90 humming, buzzing all the time

[wmwise]

Howdy everyone, I just installed single a P90 in my archtop. Went from the pickup to a 250K volume pot then to the 1/4 jack. I followed the wiring diagram that came with the pickup to a T, it sounds and plays great, but there is a constant humming or buzzing sound unless I touch the crome knob on the volume control or the crome jack plate. I have tried 2 different amps and my PA. Same thing in all of them. I am thinking that I have some type of grounding or sheiding problem, but not sure how to fix it. Any advice will be VERY helpful.

 

Thanks

Bill

[Belva]

Do you have a metal strap button? If so, can you get a ground wire to it to ground the guitar?

[normh]

Sounds like you either have a loose ground wire or else a poor solder connection on the ground plane.

[Belva]

I agree with normh. Check all connections before doing anything, as always. If that is good, you'll probably need another ground to something. Can you change the hum when you wiggle the cord? Could be bad gnd @ jack.

[wmwise]

Thanks guys, I checked all of the grounds, everything has a good solid conection, solder very hard, cant move any wires. I did try another cord, still have the hum.

 

This is starting to drive me crazy:facepalm: I know that its something simple, just cant seem to find it.

 

Bill

[normh]

The P90 is a single coil pup. It is susceptible to noise sources.

 

Did you check to see if you are under florescent lighting, near a computer, a power outlet, refrigerator, etc.? Are the positive and negative wires to the pup reversed? Are you plugging the amp into a grounded outlet?

 

If your axe is shielded, is the pup cavity shielded, is there a good connection from your ground to the cavity shield? Is the ground wire from the bridge to the ground plane or output jack connected and does it have continuity?

 

First thing to check is to see if your string ground is connected. Temporarily run a wire from your knob or from the ground inside the guitar to the bridge. Plug the guitar in and turn on the amplifier. Is the noise diminished or does it go away? If either, then you have a faulty ground to your bridge.

 

If this does not diminish the problem, reverse the pup wiring because mistakes do happen; though I think you would notice an out of phase pup. Does the problem go away? No. Return the wiring to the original configuration.

 

If the guitar is not shielded, skip for now. Run a wire from the output jack ground (and make sure that it is the ground - the sleeve) to each cavity in turn and test by playing through the amp, or at least touching the bridge or knob. When the noise goes away you have found the faulty cavity.

 

If the noise does not go away, run a wire from the sleeve of the output jacks in turn to the back of each pot. If the noise vanishes at any pot, check the connections at that pot and continue with the remainder. If a bad pot is found and there is no reason to believe the connections are bad - meaning you soldered each connection - then replace the pot. If this fails:

 

Then, or do before hand, move the amplifier to another location and power outlet (completely different circuit like kitchen to upstairs bedroom) and test. If the noise goes away you were to close to a noise source. Shield the guitar

 

I have seen the 60 hz. hum in a ballast transformer picked up by single coil pups.

 

It would be easier with a meter, but I am guessing that you do not have one.

[WRGKMC]

Sounds like you need a wire going to the tailpiece so your strings are connected to ground like any electric guitar is.

[Belva]

Which gets back to the metal strap button question. I saw this fix when I was young & stupid & it worked. (Now I'm old & stupid!)

[hasya108]

P-90 is a singular-meaning needy--little beastie. I have a

pair in my ES-295 and they do make noise. Now the check

for 'normal noise' is move all about your space w/buzzin up

loud and you should find 'null' places when it's a lot less.

If it's constant, then you have ground plane problem. There

should be solid connection on: back of each pot--both pups

--switch--bridge--tailpiece---meaning they're all solidly

connected via 1 continous lead. If you have a non-metal

bridge (wood or nylon tune-a-matic inserts) you may have

to run a wire to tailpiece as previous poster said.

Having done all that there's the AMP! It is a fact that not

all amps are created equal or even close when it comes to

input shielding and the related addition of all that noise.

If you are a musician-for-life you might as well get into

the care and feeding of input/output topography. That's where the 'moving parts' come in to play: plugging and

unplugging will eventually loosen ALL jacks/wire assemblies..these performance-sucking inevitables must

be pursued and fixed on a regular basis..my gawd when I

think of ALL THOSE TIMES that damned 'buzz' on the track

or in the mix was just another lousy plug/jack connection

that needed re-soldering or a shot of cramolin!

Always seek mechanical intermittants when tracking the

buzz-hum

[boxorox]

Hee-hee. P-90's buzz all the time. That's why they invented humbuckers. Sorry. Couldn't resist. Ground it best you can. Use a good shielded cord, and make sure your jacks are holding on tight. Drives you nuts, but they sound so good.

[WRGKMC]

I glued copper foil on the inside of my covers and cut holes for the pole pieces. Then solderd an extra ground wires to the foil. Cut a good deal of hum down.

[wmwise]

Thanks for all of the great advice everyone!!! I did all of the ground checks ect that you had posted, made sure that I did not have the wires crossed, hum still there. So I added ground wires to the tune-o-matic bridge and to the bridge, added the copper foil to the pickup cover and grounded that also. That cut the hum to about half of what it was. I can live with that.

 

Then I was thinking, my house was built in the 1940,s so the wiring might have alot to do with it.

 

This was my first electric build, I converted a 1940 archtop hollowbody acoustic into an electric. Now that I have the humm down to a low level, I just love the sound of the P90. Gives it that vintage sound I was looking for.

 

Thanks for all of the great help!!!!!!!!!!!!!!!!!!!!!

 

Bill

[Belva]

Glad it's working out. Just curious; can you find another house to play? That might eliminate the rest of the hum

[normh]

 

Then I was thinking, my house was built in the 1940,s so the wiring might have alot to do with it.

 

 

Tell me about it. Just moved into a house built in 1915. Beautiful home but the wiring is so old that it has asbestos insulation and is two wire even though all the sockets are three prong. The walls are plaster over lathe. Had to run ground wires to a few "equipment rooms. Lots of fun. Some of the sockets in the worst place, the kitchen, I can not ground without tearing out walls.

[Belva]

This would be a good trouble shooting step. Go to a buddy's place, set up & play. If there's a noticable difference in hum, you got it solved. I've seen clubs that, electrically, were so dangerous I wouldn't play there. P90's there would suck!

[mrbrown49]

 

This would be a good trouble shooting step. Go to a buddy's place, set up & play. If there's a noticable difference in hum, you got it solved. I've seen clubs that, electrically, were so dangerous I wouldn't play there. P90's there would suck!

 

 

Yeah, it's really to hard to get rid of all the noise if you don't have control over the source. Even if an instrument is totally shielded, the pups will still pick up some of it. At home, it's possible to deduce to some extent which devices are causing noise issues and eliminate them when recording and playing; lighting fixtures, Computer monitors, dimmers, etc.

[wmwise]

Howdy again, I did have a chance to take the guitar and amp over to a friends house (only 3 months old) and guess what..... alot of the humm was gone. So it looks like the old 2 wire wiring that my house has ALOT to do with it.

 

We played for about 2 hours, we had a great time. Now he is trying to talk me out of my build. He cant beleive the tone and sound that I am getting out of this.

 

I think that I am going to try a set of flat wound strings and see how they sound.

 

Thanks for all of your GREAT help everyone!!!!!!!!!

 

Bill

[Bubbalou]

You can run a ground from a two wire with ground duplex recepticle to a cold water pipe (clean area of pipe you wish to put a metal strap around to hold the wire). You can also use a good copper clad grounding rod instead of the cold water pipe. I would run 12 or 10 awg wire for your ground.