Weird, constant, inaudible B note?

[xardoz]

Hi everyone. If this is the wrong forum, I apologize, but I could really use some help.

I recently built my own guitar and it's fine, but a buddy liked it so much that he asked me to do a setup and general diagnostic on a few of his guitars.

He's handed over two of them so far, and the first, a late '70s Castilla Strat copy, seemed to be generating a constant, sweeping B note, flat to sharp, back and forth. The note wasn't audible, but showed up when using a digital tuner, making it tunable only by ear.

I used two different tuners (one battery powered, one integrated in a new amp), several different cables, in different rooms and even in different houses and the signal persists, so it's not the power, tuner, cable or environment. This does not happen on my guitars, even my home-built one.

Everything seemed to check out on my multimeter, so I pulled the pups and tested them by themselves, hooking the leads directly to a good, shielded guitar cable. The bridge and neck pups generated the signal, but not the middle pup. I tried reversing the connection (pup positive to jack negative) and back again, but it kept reading the same.

Taking this as a symptom that two pups were bad, I rewound them to the same resistance and the problem went away. I've buttoned the Castilla back up and she plays beautifully now.

Now it gets weird. The second guitar is a 1980s Series 10 violin bass with what I'm assuming for now to be humbuckers. And it's doing almost the same thing. The B signal doesn't sweep like the Castilla did, but rather comes in at a constant B flat.

Does anyone have any clue what is going on here? I'm starting to wonder if his guitars aren't haunted.

[JohnH]

Welcome to GN2. I dont know what is happening there, but I would note that US mains frequency at 60Hz, and its harmonic at 120Hz, are pretty much 'B' notes (slightly flat - actually, the nearest B is 123 Hz) - so maybe mains related?

John

[thetragichero]

i have my rack tuner hooked up to just the clean channel on my preamp, and when i'm in one of the other channels it reads as B.... so more than likely it's what john said

[xardoz]

Thanks, guys!

Well, it doesn't happen with my guitars on my Mustang II's internal tuner, nor on my guitars via my Korg CA-1 chromatic - which is battery only.

Just throwing it out there, but my friend pretty much plays through old solid state amps, although he was playing through a Fender Princeton silverface tube amp as well until that went belly-up after sitting in his car's trunk ("boot" for you, John, if I'm not mistaken) for months on end.

Could it be that one of his amps had a mains problem and "burned" (for lack of a better term) that B signal into the pickup coils? Rewinding the coils on the Castilla pickups solved the problem there, but if one of his amps is causing the problem, I'd rather not have to rewind them again. I can get replacement pickups for the bass, though.

[newey]

I don't believe in the amp potentially "burning a B♭ note" into the pickups any more than I believe your buddy's guitars are haunted.

Facts (the pertinent ones, at least . . .):

• Neither one of your friend's guitars is a high-end model. One's a "Castilla" and the other a "Series 10". Presumably, both brands used a cheaper range of pickups.
  
  
• Pickups, especially cheaper types, can degrade with age and may not be as quiet as they once were. Both of these guitars are over 20 years old, and (we are led to assume) these are the original pups on both.
  
  
• US mains frequency is 60Hz, about a B♭. Both guitars in question are producing noise at/around the frequency we would expect for mains noise.
  
  
• However, by your own description, these guitars are NOT behaving identically- similarly, yes, but not identically.
  
  
• Rewinding one of two sets solved the problem in that set; no similar operation yet performed on the other pair.
  

Based on these items, one could reasonably conclude that:

• The noise is from the household mains.
  
  
• It is being picked up by your friend's older, noisier pickups, which is why you don't hear it with other gear, and why your friend's guitars exhibit this noise across multiple testing platforms.
  
  
• While both sets of pickups have exhibited similar problems, each has degraded in its own way (as would be expected), thus the noise produced by each varies somewhat- because the defect they exhibit differs from one to the other.
  
  
• The cure is rewinding/replacement, since the problem lies in the pickup windings. Potting the coils might help, but no guarantees there, that's more for microphonics.
  

EDIT: Where are my manners? Hello and Welcome to G-Nutz2!

[xardoz]

Thanks, Newey! Yes, both of his guitars are lower end - the Castilla is downright cheap. I rewound the pups because the guitar is oddly sized and shaped (more of a Strat tribute than an outright copy), and that includes the pups. Off-the-shelf replacements won't fit, and a stock Strat pickguard won't either. "Rode hard and put away wet" would be a good description of the overall condition, too. But it was his first guitar, and he loves it.

None of the guitars in this situation are shielded, either, but mine are newer and better cared for. (Squier, Ibanez, and a month-old homebrew I call the Red Witch.)

So what you're saying does make sense - thanks for breaking it down into bullet points.

I've found a source for some replacement pups for the bass, so I'll probably swap those out

Thanks, everyone, for the input and encouragement - I think newey's got it nailed.

[newey]

On the topic of pickups aging, and in order to explain the somewhat-coincidental nature of the fact that 2 guitars, both belonging to your friend, are exhibiting similar behavior (although perhaps not identical) . . . . .

Warning! Supposition and guesswork ahead!


If I were inclined to speculation, I might hypothesize, even in the absence of any evidence, that the reason your friends 2 guitars behaved similarly was by virtue of the fact that they were both his guitars . . .

Meaning they had traveled with your friend from place to place for 20 -30 years. Both were probably stored under similar conditions over the years. If we posit that, at some remote point, both guitars were subjected to similar extreme conditions, it might explain the similar outcomes years later..

Did your friend live in a dry desert clime, perhaps? Or, perhaps the opposite, a tropical area? Does he sweat onstage into his pickups, and is his sweat uniquely corrosive in some way? (Just kidding on that last! ;D)

Old pickups can degrade in several ways. One way is that, on older pickups, Fender used to apply a coat of lacquer to the coils for some "potting" effect. Many other manufacturers did likewise, after all, if it was good enough for Fender . . .

Temp and humidity extremes can, over time, crack off this lacquer coating just like a finish crazes over time.

Some will swear this is what makes the old ones have that elusive vintage mojo. But it definitely can make them noisier.

But again, even with no evidence, my best theory is a similar storage issue for both guitars many moons ago.

[sumgai]

Well, this certainly gained traction in a color-within-the-lines sort of way, didn't it though......


newey comes close, but still not quite hitting the correct note (pun highly intended): the problem is mechanical resonance. The bridge in particular, but other parts too, can resonate with the strings such that it seems to always vibrate at a given frequency - which of course comes back through the strings, and thence on into the pickemups. Oddly enough, B or a bit lower seems to be a commonly reported frequency, when this crops up.


Rewinding the pickups isn't what fixed it, its the fact that new strings were put on afterwards, and 10'll get you 20, the bridge setscrews weren't in exactly same position when it was re-strung - end of resonance, at least for awhile.



Oh, and while I'm at it.......

xardoz,

Hi, and to the NutzHouse!


HTH






sumgai

[gumbo]

...makes me soooo glad we've got 240v.... ;D

[xardoz]

Newey: Good points re: environment of HIS guitars.

sumgai: I get what you're saying about mechanical resonance, but why would the pickups continue to generate the B tone after I had completely removed them from the guitar? They were sitting on my work table, hooked to the tuner via alligator clip leads and the guitar in a stand on the other side of the room

[newey]

What was the saying? And who said it? (Sir Francis Bacon, maybe?)

"A beautiful theory, killed by an ugly fact . . ." ;D

[xardoz]

Also, Hi everyone, and thanks for the warm welcome!

[cynical1]

...I'm leaning towards gremlins...

HTC1

[ashcatlt]

Series 10 was a fairly popular brand of low-to-mid priced guitars built mostly in the 80s and early 90s by a company named Bentley. I think they eventually sold to Jackson. I was intimately involved with four of them in the early days of my career. I had an HSS strat in black-with-yellow crackle which was just a bit better player than the baseball bat it replaced. My girlfriend at the time had a much nicer strat style with a bound top, Floyd Rose, and individual toggles for pickup selection (the bridge HB was splittable) that had a much slimmer neck and was really kind of a nice shredder. I talked her into trading that for a black with flowers tele copy with which I fell in love - it played and sounded beautiful. Then I got a bass of theirs that was a rip off of that solid body with f-holes thing who's name I can't remember right now. This was also a nice playing bass for the price.

It's strange that you can't hear anything happening, but am I correct that you can't get the tuner to register the actual strings over this constant tone? Is there any chance you can connect these pickups to a computer and record the signal? Then you could hit it with a spectrum analyzer and get some better idea of what's actually going on.

Also, do you happen to have a metal box you could stick the pickup in for testing? You'll need to make sure the box itself is grounded via the cable shield, but it might tell us something.

[newey]

Then I got a bass of theirs that was a rip off of that solid body with f-holes thing who's name I can't remember right now. This was also a nice playing bass for the price.

Just so you don't lose any sleep wondering, ash, it was an Ampeg "scroll bass" (or a copy thereof). In the '60s, Ampeg made both a bass guitar as well as an EUB version.


If you want one now, there's a guy in SoCal who'll make you one for the right price:

www.xstrange.com/

[xardoz]

Aug 3, 2011 11:48:29 GMT -5 ashcatlt said:

Series 10 was a fairly popular brand of low-to-mid priced guitars built mostly in the 80s and early 90s by a company named Bentley. I think they eventually sold to Jackson. I was intimately involved with four of them in the early days of my career.

My friend really liked them at the time, and he has one of their Ric 330 copies that made it over before the lawsuit hammer fell. Nice little guitar, especially for the price.

It's strange that you can't hear anything happening, but am I correct that you can't get the tuner to register the actual strings over this constant tone?

On the Castilla, yes, but it's difficult. On the bass, it's almost impossible.

Is there any chance you can connect these pickups to a computer and record the signal? Then you could hit it with a spectrum analyzer and get some better idea of what's actually going on.

That's getting beyond my abilities and equipment right now.

Also, do you happen to have a metal box you could stick the pickup in for testing? You'll need to make sure the box itself is grounded via the cable shield, but it might tell us something.

That might be possible. He's approved swapping out the bass pups, so I could give it a try then.

[ashcatlt]

xardoz said:

My friend really liked them at the time, and he has one of their Ric 330 copies that made it over before the lawsuit hammer fell.  Nice little guitar, especially for the price.

Had a friend with one of those back in the day.  The bolt-on neck was unacceptable.  Course I had a real Ric, and worked at a place which sold them...

I'm still badgering the person who has that Tele to sell it back to me.

That's getting beyond my abilities and equipment right now.

You've got a computer?  It's got onboard sound or a soundcard?  The rest is easy.