P90 noise when bending strings

[jorge rodriguez]

Hi all,

I recently rewound an old P90 from the 1950s as it wasn't working. The sound is good and it just has the normal amount of "hum" that this pickups have, but it seems to create a strange kind of "scratching" sound when the strings are bent. It's not too bad, but just enough to be bothering. I suppose it might be something related to the magnetic field (?), but I don't know what.

If anyone could help me it'd be much appreciated.

Thanks in advance,

Jorge

[Greg Robinson]

Hi Jorge,
How well polished are your frets? If this only happens when bending, I would suspect them first.

[jorge rodriguez]

Hi Greg,

Thanks a lot for your reply. The frets are ok, actually I refretted the guitar so I polished them. In fact I think the noise is electric, I said like a "scratch" because it's the best way I found to describe it, it's similar to the noise of a dirty pot when you turn it, but it happens when you bend the strings. I think it comes from the pickup, but then again I cannot be 100 % sure.

Cheers,

Jorge

[Mark Swanson]

Does the string hit or rub against a pole piece as it is bent or played? Check that really good, it can be decieving at times. To test it, lower all the pieces, then try it, or just take a good look. It could also be a screw that could be loose enough to rattle. Did you pot the pickup in wax?

[jorge rodriguez]

Hi Mark,

Thanks for your reply.

No, the strings don't hit the polepieces, they're about 1/8' below the strings. But I'm thinking that maybe it could be something that vibrates when the string is pulled, I will check everything... thanks!

Jorge

[jorge rodriguez]

Does the string hit or rub against a pole piece as it is bent or played? Check that really good, it can be decieving at times. To test it, lower all the pieces, then try it, or just take a good look. It could also be a screw that could be loose enough to rattle. Did you pot the pickup in wax?

And yes I did pot the pickup, I tried it before potting, it was squealing very badly when I turned up the gain a bit, but that is all gone now.

Cheers!

[Joshua Levin-Epstein]

Check to see if there is a loose bit of steel wool captured between the strings and the polepieces. That's my favorite.

Joshua

[jorge rodriguez]

Check to see if there is a loose bit of steel wool captured between the strings and the polepieces. That's my favorite.

Joshua

Oh that might be it! I cleaned it because there was some steel wool on the pickup, but I might have to check again... Thanks!!!

[David King]

Jorge,
Is there any chance you could have a dc voltage differential between the frets and the strings? Could it be you are wearing a polyester shirt and that static electricity is building up on the plastic control cavity cover or the pick guard and feeding into the output? These are way far off ideas but a possible explanation.

Masking tape is the easiest way to remove steel wool particles. Keep applying, removing and checking the stickum until no contamination is left on the tape.

[jorge rodriguez]

Hi,

Thanks all for all the replies. It was finally something different to everything suggested, but everything made me think so in the end I found the problem and therefore the solution.

It's an archtop guitar (Gibson ES-125), so it has a tailpiece. The ground connection to the tailpiece was not good, so when I pulled the strings the tailpiece moved, even if just a little bit, so this cause the connection to fail and cause the noise.

Now it's fixed. Thanks everyone again!!!

Regards,

Jorge

[Mark Swanson]

Wow, that's a new one. Thanks for coming back and posting the end result! I'm glad you found it.
This is one more lesson for us all, that is if you hear something wrong somewhere, there IS a reason and an answer, no matter how hard to find.

[John Mueller]

Why don't guitars with ebony tailpieces have this problem?

[Mark Swanson]

There are many different tricks to get a guitar string grounded. If it is not string grounded it WILL have that problem, and if it is grounded right then it won't. Some builders find unique ways to string ground a guitar with an ebony tailpiece. Many guitars with ebony tailpieces are jazz-type archtops that use humbucking pickups and cleaner, bassy low-gain settings when played. If it isn't string grounded then you won't hear much buzz then, but if you use a lot of gain, play loudly and have more high end in your tone it'll buzz like mad.

[Chuck Raudonis]

I was looking at a pre-owned guitar (just can't bring myself to call it used when it has a $3k price tag on it) that was a custom build. The guitar was a maple hollow body, all natural, all carved, beautiful instrument. When I played it, the sound was like magic but there was buzz like crazy. Even with my fingers on the strings, it sounded like a buzz saw. I looked and sure enough, the tailpiece didn't have any grounding strap to it. It was ebony and didn't have a metal strip to make contact with the strings and no wire to connect it. I was confused. This was a quality build. The guy selling it was a reputable dealer, one of the biggest names in the business and he pretended to not know what I was talking about. He blamed it on faulty wiring in his building. I plugged in another guitar and the buzz magically went away when I touched the strings. I'll give him that his wiring might be bad but the second guitar dealt with it with grounding. He STILL argued the point that it was the shop's wiring and there was nothing wrong with the first guitar.

After I left the shop I tracked down the original builder and told him what I found. He looked at pictures of the guitar on the broker's website and sure enough, that was not his tailpiece. The original owner swapped out a cello style tail for the original and didn't know enough to ground the damn thing! It was funny because when he told me that I remembered that the tailpiece didn't look right and didn't quite line up. BINGO!

Well, Mr. Bigshot Big Name dealer went down a couple of notches in my opinion and I decided that I would never buy from him EVER.

Lesson learned, always ground the strings.

[Mark Swanson]

I agree Chuck, that is terrible!