Unidentified buzz

Construction and repair of Classical Guitar and related instruments
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attila57
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Unidentified buzz

Post by attila57 » Mon May 29, 2017 9:07 pm

Hello fellow Delcampian Luthiers,

I have a cheap Chinese guitar that has a serious buzz issue. I checked everything, and it seems to me that the buzz originates in the neck itself or in the head of the instrument. I removed every hardware and the buzz is still present if I tap the instrument. Anyone had a similar problem?

Attila
Music to hear, why hear'st thou music sadly?
Sweets with sweets war not, joy delights in joy...

William Shakespeare, Sonnet 8

Alan Carruth
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Re: Unidentified buzz

Post by Alan Carruth » Tue May 30, 2017 5:53 pm

The place where the buzz originate may have nothing to do with where the sound is being produced. The sound emanates from the place on the guitar that is best able to put out that pitch, usually the top or the bridge.

I'm told that somebody has listed every known source of a buzz on a guitar: it's well over 200 things I believe. Buzz hunting is every repairman's nightmare, right up there with intermittent problems. You can narrow the field a bit, though.

Does the buzz occur at some particular pitch? Sometimes a loose part will vibrate at a certain frequency, or it could also be a 'wolf' of some sort caused by clashing resonances. The latter is unlikely in this case, since with no hardware you can't tune the strings, so there's noting much to drive a wolf.

Try tapping sharply around on the top and the back with the flesh of a finger tip. The objective here is to get a hard, quick tap, but not so hard that you're in danger of punching a hole in the top. Tap particularly over the location of braces. Sometimes you can hear the buzz when you hit the right spot.

Is the neck reinforced? If it has an internal rod of some sort that can buzz. Often new guitars come with no tension on an adjustable rod, and simply tightening it up, as should be done when the strings have been mounted, can eliminate the buzz. And sometimes not....

Get a small mirror and a light and look inside. Is there anything loose in there?

We once got a guitar in that had a terrible buzz; by far the worst I'd ever heard. It was a cheap import that somebody had just bought from another store, or maybe on line. When we looked in there was a piece of metal cut from a can inside. One end had been glued under a brace when the top was constructed, and the other end was bent around in a loop to where it almost touched the top. at the 'right' frequency all hell broke loose. A clear case of sabotage.

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Jacek A. Rochacki
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Re: Unidentified buzz

Post by Jacek A. Rochacki » Tue May 30, 2017 6:49 pm

I know a similar case - it was not typical buzz, rather unpleasant metallic like after sound. It appeared after change of strings and trying another set of strings did not help. Also changing saddle and nut did not bring any positive results. Of course the geometry of the instrument was checked even the guitar played well for a year or something.

After checking that there are no loose elements inside (like @ Alan Carruth wisely suggests) I was advised by helpful constructor of this guitar to oil/lubricate with thin, machine oil nests carved in wood of the head of the instrument where the ends of rollers are "nested". I heard that it some cases it may help, unfortunately this was not the case of the guitar in question.

Finally I examined the inside of the guitar with endoscope. And to my astonishment I spotted the ...ball of dust of diameter ca 5 mm. (sic!) that was jammed between some wooden elements inside the guitar. I was not prepared for it, as the guitar is well taken care of, all the time it is kept in hard case and it is played in very clean room. By long tweezers the ball of dust (in consistency of felt) was removed - and since then the guitar plays well again.

I wonder how this ball of felt-like in consistency dust appeared there. Is it possible that the sound waves gathered and put together the dust ? I do not know.

Perhaps your guitar suffers from similar, non typical "disease" ?
Antonio Picado, model 60, 2015, Cedar/IRW. Scale 640 mm.

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Michael.N.
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Re: Unidentified buzz

Post by Michael.N. » Tue May 30, 2017 7:07 pm

The worst case that I've encountered was on a starved fretboard joint, just over the soundboard, except the edges were firmly glued. I can't begin to tell you how long that took me to find. The only reason that I did find it was because I was using tuning forks to try and pinpoint the problem. I had also eliminated everything else multiple times! There's nothing quite like a mysterious buzz to bewilder the mind. Thankfully most are somewhat easier to find.
Feeler gauges are good for checking joints inside the body, thin enough that they will slide into a gap yet thick enough that they still have enough resistance. Sometimes you have to put them on a wooden arm to enable you to reach further into the hard to reach places.
You can also stuff the guitar body with cloth if you want to try and isolate the neck.
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Andrew Pohlman
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Re: Unidentified buzz

Post by Andrew Pohlman » Tue May 30, 2017 7:18 pm

No insult intended, but practicality dictates that you spend no further time on a cheap guitar. It is feasible that for the cost of the time you spent already, you could have bought a better guitar. Now if you are practicing guitar repairs and this is a learning curve, that's a different story.

A friends electric bass had a bizarre buzzing and he said he could feel it in the neck. It turned out to be what Alan said - loose truss rod. We tightened that up to remove the slack, and problem was solved.

Good luck!
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Alan Carruth
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Re: Unidentified buzz

Post by Alan Carruth » Wed May 31, 2017 5:32 pm

Jacek A. Rochacki wrote:
"And to my astonishment I spotted the ...ball of dust of diameter ca 5 mm. (sic!) that was jammed between some wooden elements inside the guitar."

The Tone Ball! ;)

A violin maker and repairman I know called a customer up once to say that his instrument was ready to be picked up. The fellow asked if he'd re-installed the tone ball, which this customer apparently felt was the 'Secret of Stradivari'. "Oh, of COURSE!" said my friend. As the fellow was driving over to get his fiddle my friend opened up several old junker instruments and made up a nice, big tone ball, which he stuffed into the hole as the customer arrived. We discussed marketing them: wool and linen ones for 'authentic' Early Music performances, polyester ones for music from the '70s, crystal tone balls for 'New Age' music and so on. Texas fiddlers already put rattlesnake rattles into their instruments to make the sound 'bite'. I kid you not.

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Jacek A. Rochacki
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Re: Unidentified buzz

Post by Jacek A. Rochacki » Wed May 31, 2017 6:05 pm

Alan - thank you for enlightenment. I was really surprised to find this thing inside my guitar, and after removing it the guitar sounds beautiful again.
Antonio Picado, model 60, 2015, Cedar/IRW. Scale 640 mm.

Paul Micheletti
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Re: Unidentified buzz

Post by Paul Micheletti » Wed May 31, 2017 6:07 pm

I love your posts Alan! That one was hilarious! :lol:

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attila57
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Re: Unidentified buzz

Post by attila57 » Mon Jun 12, 2017 11:00 pm

Michael.N. wrote:
Tue May 30, 2017 7:07 pm
The worst case that I've encountered was on a starved fretboard joint, just over the soundboard, except the edges were firmly glued. I can't begin to tell you how long that took me to find. The only reason that I did find it was because I was using tuning forks to try and pinpoint the problem. I had also eliminated everything else multiple times! There's nothing quite like a mysterious buzz to bewilder the mind. Thankfully most are somewhat easier to find.
Feeler gauges are good for checking joints inside the body, thin enough that they will slide into a gap yet thick enough that they still have enough resistance. Sometimes you have to put them on a wooden arm to enable you to reach further into the hard to reach places.
You can also stuff the guitar body with cloth if you want to try and isolate the neck.
Hello Michael,

Thanks for your valuable advice! I also suspect that the fretboard joint might be starved, or, alternatively, there might be some loose particles or a piece of broken wood trapped in a channel in the neck. Factory-made necks often have channels routed into them, presumably to make them lighter. Another possible culprit might be the headstock itself, being too pliable without proper headstock cover.
Stuffing the body is a nice idea indeed!

Attila

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attila57
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Re: Unidentified buzz

Post by attila57 » Mon Jun 12, 2017 11:13 pm

Andrew Pohlman wrote:
Tue May 30, 2017 7:18 pm
No insult intended, but practicality dictates that you spend no further time on a cheap guitar. It is feasible that for the cost of the time you spent already, you could have bought a better guitar. Now if you are practicing guitar repairs and this is a learning curve, that's a different story.

A friends electric bass had a bizarre buzzing and he said he could feel it in the neck. It turned out to be what Alan said - loose truss rod. We tightened that up to remove the slack, and problem was solved.

Good luck!
Hi Andrew,

Thanks for your advice! You're right, I should have given up the search, considering the value of the instrument. But somehow it annoys me that I can't find the source of this buzz. Apart from that, the instrument is not so badly built for a cheap Chinese guitar. It could be used well for busking or for a travel guitar...

To all contributors to this thread: thanks for the advice!

Attila
Music to hear, why hear'st thou music sadly?
Sweets with sweets war not, joy delights in joy...

William Shakespeare, Sonnet 8

Keith
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Re: Unidentified buzz

Post by Keith » Mon Jun 12, 2017 11:40 pm

Attila, when you say you removed all of the hardware I take it that means the tuners as well. If the tuners were removed I would imagine the strings were as well. Since the buzz remained we probably can eliminate the tuners, strings, frets, etc. It could be a crack in the neck, head or neck joint. A couple of months ago I bought a guitar which had a weird buzz to it which irritated the crap out of me. I did the obvious--check for loose strings, screws, frets, etc. The frets needed leveling which was done and the buzz became sporadic. I finally discovered the culprit--a crack in the head where the tuners fit in. Tuners were pulled and the head got a visit from Mr. Tite-Bond and his friend, clamps. Problem solved and frets were leveled. Start checking for pesky cracks inside and out.

One interesting side benefit of the events described above was I was put in a frame of mind to check out other guitars and found a really great one which I purchased. Your situation might be the catalyst for you to begin your search.
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Ben B
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Re: Unidentified buzz

Post by Ben B » Sat Jun 17, 2017 3:22 am

I've got a 70's(+/- a few years), Yamaha/ nippon gakki , G100-A that has a really great tone...
...but, a buzzing D string. I originally swapped nut and saddle with some spares, to no avail.
Then I leveled tje frets, and re-crowned where they were a little flattened. no help with D buzz.
(I tried new string/s in the midst of this), no help with buzz/rattle.
Then I decided to remove & repl. finger board, and re-fret.
I used a piece of birdseye maple I had laying around.
When I went to drill a 1/16" hole at 11th fret, for an alignment pin, I hit metal.
My hole was deep enough, so i left the reinforcement? rod alone.
After new FB, and new frets, still exact same D buzz/rattle.
Ive heard of a sound board getting "an over-driven" effect, if it's towards the thin side.
Thats what it sounds like to my ear, anyways.
I plan to remove 2nd and 11th frets, drill into that rod, and press very slightly larger pins into the rod...
any advice would be greatly appreciated.
I'll post back my results, good or bad
thnx

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attila57
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Re: Unidentified buzz

Post by attila57 » Fri Jul 28, 2017 6:07 pm

Keith wrote:
Mon Jun 12, 2017 11:40 pm
Attila, when you say you removed all of the hardware I take it that means the tuners as well. If the tuners were removed I would imagine the strings were as well. Since the buzz remained we probably can eliminate the tuners, strings, frets, etc. It could be a crack in the neck, head or neck joint. A couple of months ago I bought a guitar which had a weird buzz to it which irritated the crap out of me. I did the obvious--check for loose strings, screws, frets, etc. The frets needed leveling which was done and the buzz became sporadic. I finally discovered the culprit--a crack in the head where the tuners fit in. Tuners were pulled and the head got a visit from Mr. Tite-Bond and his friend, clamps. Problem solved and frets were leveled. Start checking for pesky cracks inside and out.

One interesting side benefit of the events described above was I was put in a frame of mind to check out other guitars and found a really great one which I purchased. Your situation might be the catalyst for you to begin your search.
Hello Keith,

Thanks for the advice! I had thought of that possibility myself, too, and even wanted to remove the headstock overlay to examine the headstock, but I didn't. Somehow I had the feeling that the buzz was coming from inside the neck. Eventually, on a nice day I felt the irresistible urge to remove the fretboard. I did it with a heat gun. Underneath I found two channels routed into the wood along the neck. Two 20 cm long metal rods had been inserted in the channels in such a lousy way, that the wood separating them was all broken. Epoxy had been used to hold the metal rods in place, but it had come loose. Possibly it was its free movement, and the sideways movement of the metal rods, plus the resonance of the broken wood, which caused the nasty rattling upon every plucking of a string.
rods-3.jpg
rods-2.jpg
rods-1.jpg
As a remedy, first I forced the metal rods out of the channels with a screwdriver. Then, with a router, I made a wider channel (1.5 cm wide) by enlarging and cleaning the existing channels, and removing the splintered ridge from between them. Then I cut a suitable length of hardwood and glued it it the new, wide channel with Titebond.
clamps-1.jpg
Glueing in the hardwood inlay is a bit tricky. To ensure a proper bond between the sides of the channel and the inlay one needs to serrate the sides of the inlay, so that the excess glue can find its way out, and so that there could be a slight gap between the surfaces to achieve a glue joint which is not starved. It is best done with a miniature triangle file. The serrations should be at right angles to the length of the channel.
clamps-3.jpg
When the glue had dried, I removed the clamps and with a scraper, I brought the top surface of the wood inlay roughly level with the top of the neck.
scraping-1.jpg
This is where I am now. In the days to come I'm going to put on a new ebony fingerboard with 20 frets, a rosewood headstock overlay, a rosewood-inlayed bone bridge overlay and an all-over shellac finish. I'll let you know about the results.

Attila
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Music to hear, why hear'st thou music sadly?
Sweets with sweets war not, joy delights in joy...

William Shakespeare, Sonnet 8

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attila57
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Re: Unidentified buzz

Post by attila57 » Mon Jul 31, 2017 6:28 pm

Leveling the hardwood inlay.
IMG_20170730_205210_310.jpg
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Last edited by attila57 on Mon Jul 31, 2017 6:37 pm, edited 1 time in total.
Music to hear, why hear'st thou music sadly?
Sweets with sweets war not, joy delights in joy...

William Shakespeare, Sonnet 8

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attila57
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Re: Unidentified buzz

Post by attila57 » Mon Jul 31, 2017 6:29 pm

Making a new fingerboard...
The old one (right) is too thin and too flexible.
plane.jpg
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Music to hear, why hear'st thou music sadly?
Sweets with sweets war not, joy delights in joy...

William Shakespeare, Sonnet 8

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