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Strange Resonance
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=50785		 Page 1 of 1
Author:  Spyder [ Tue Jul 03, 2018 5:15 pm ]
Post subject:  Strange Resonance
OK, a real head scratcher here. After sitting for a couple of months, thought it was time to tweak No.1 a bit. idea was to simply lower the action on a few strings to make it easier to play. So I carefully marked the nut with a half pencil, and deepened the slots on the top two strings (B & E) Now the B string buzzes like crazy, but only when played open. Looked at many things, eliminated most all, now I realize I have a strange situation going on here. This is the rundown:

String plucked in open state creates buzzing like crazy, sounds terrible.
Tightened: truss rod, both neck bolts, no change.
Checked for clearance over first fret, plenty, maybe even could come down a bit more. In other words, not touching anything.
Ran file back through the slot to make sure it wasn't angled wrong. Seems fine.
Holding pressure on string between nut and tuner makes no difference.

Result of all this is, this is a resonance problem. Tune that string up or down a half step, buzz goes away.

So here is the apparent fix: hold an E string tuning knob. Pressure of fingers makes buzz go away. Works on either side, high or low. So I tightened all the screws, no change. Only thing that seems to help is to grab the tuner knobs of those two, which are not even the string that is causing the buzz. Note that tuners are three on a plate.

Anyone ever run into this? Only thing that changed, best I can tell, is the B string is now sitting a touch lower in the nut than when I started, but when played open it sets up a resonance buzz in the tuners on the E strings. Any ideas?

Thanks, this is driving me nuts. Again! gaah
Author:  SnowManSnow [ Tue Jul 03, 2018 5:35 pm ]
Post subject:  Re: Strange Resonance
Is your truss rod buzzing some how?


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Author:  Spyder [ Tue Jul 03, 2018 5:36 pm ]
Post subject:  Re: Strange Resonance
If it matters, this is a slot head design. Not sure what that might have to do with it, but those two are the closest together.
Author:  Spyder [ Tue Jul 03, 2018 5:37 pm ]
Post subject:  Re: Strange Resonance
SnowManSnow wrote:
Is your truss rod buzzing some how?


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That was my first thought, so I tightened it a quarter turn. Made no difference. Still haven't eliminated it completely, but at least did try that much.
Author:  bluescreek [ Tue Jul 03, 2018 6:18 pm ]
Post subject:  Re: Strange Resonance
if it sounds like a zitarish buxx it is your nut. You may have ramped the nut slot and this can open the string rising it off the nut that causes a funny buzz and seeing that you just worked the nut I bet you ramped the slot. Think roller not ramp
Author:  Freeman [ Tue Jul 03, 2018 6:21 pm ]
Post subject:  Re: Strange Resonance
Did you actually lower to the pencil line? What exactly is your first fret clearance? Do you have clearance at the first fret when you fret the B string at 3? What is your relief (before and after tightening the t/r a quarter turn)?
Author:  Ken Lewis [ Tue Jul 03, 2018 6:57 pm ]
Post subject:  Re: Strange Resonance
" You may have ramped the nut slot and this can open the string rising it off the nut that causes a funny buzz and seeing that you just worked the nut I bet you ramped the slot. Think roller not ramp"

+1

My thoughts as well.
Author:  Clay S. [ Tue Jul 03, 2018 7:38 pm ]
Post subject:  Re: Strange Resonance
Stick a piece of cotton or similar under the string in the slot and see if the buzz goes away.
Author:  Spyder [ Tue Jul 03, 2018 7:59 pm ]
Post subject:  Re: Strange Resonance
Thanks for the suggestions, here are some answers and a few more pieces to the puzzle:

Cloth under the string -no change
Sound - metallic, not sitarish
Clearances: B string to first fret = .012/.013"; Free state clearance low E string to 12th fret - 1/8". Free state clearance High E and B strings to 12th fret - 1/32" less, or approx. 3/32". Fret B string at 3rd fret, have clearance on 1st fret, less than .004" on second (if not touching.)

OK, so here's the next bit of data: I can cause the buzzing with other strings if I play a B note on them. To check the clearance of the B, I loosened the high E. As I was bringing it back up to pitch, I noticed when it reached the same tuning as the second string, the buzz came back until I tightened it further. Then, I fretted the third string at the 4th fret, and that also causes the buzz.

This leads me to believe it is a problem of resonance, not clearance or nut slots. I do have another set of tuners, wondering if I should swap them out and see if that makes a difference.
Author:  Freeman [ Tue Jul 03, 2018 9:29 pm ]
Post subject:  Re: Strange Resonance
It sounds like you've (mostly) ruled out a string buzzing on a fret. Try down tuning a semi tone, does it still buzz? Is it a B still or Bb? Check that the ball ends of the strings are seated (look with a mirror). Try changing strings. Try a different string gauge. Tap all over the guitar listening for rattles or buzzes. Tighten bolts (neck, tuners, anything else). Check wiring if there is any. Check weird stuff (I once has a loose pick guard on an old guitar that drove me buggy). If you don't have a stethoscope try putting the handle of a long screw driver against your ear and the tip on the bridge and nut and all over the guitar (be really careful of scratches).

Report back
Author:  jac68984 [ Tue Jul 03, 2018 11:17 pm ]
Post subject:  Re: Strange Resonance
I’d agree with the recommendation to change strings. Weird things can happen putting the same set back on after nut or saddle work. If that doesn’t work, and you still suspect a resonance issue, try adding some weight to the top with some double stick tape or Scotch adhesive putty.



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Author:  bluescreek [ Wed Jul 04, 2018 5:38 am ]
Post subject:  Re: Strange Resonance
if you didn't have this prior to the nut adjustment and not you have it , it is in your nut.
Author:  gregorio [ Wed Jul 04, 2018 5:38 am ]
Post subject:  Re: Strange Resonance
I had a similar problem once and it turned out to be the actual tuning button. It made a lot of noise at a certain frequency. It wasn't noticeably loose so it wasn't that obvious. After I tightened it down that solved my problem.
Author:  Mike Baker [ Wed Jul 04, 2018 6:57 am ]
Post subject:  Re: Strange Resonance
gregorio wrote:
I had a similar problem once and it turned out to be the actual tuning button. It made a lot of noise at a certain frequency. It wasn't noticeably loose so it wasn't that obvious. After I tightened it down that solved my problem.

This. Check the mounting screws as well, slothead or not.
Author:  bluescreek [ Wed Jul 04, 2018 10:17 am ]
Post subject:  Re: Strange Resonance
Go with changing the string
I would take the B off and see if the B harmonic comes back
Like I said if you didn't have this before your nut adjustment my money is on the nut. Not only on the ramp but side to side .
Author:  Spyder [ Wed Jul 04, 2018 10:19 am ]
Post subject:  Re: Strange Resonance
To answer a few more (and repeat myself in case it was missed) I did tighten screws. ALL screws. Every mounting screw on the tuners, every tuning post, both neck bolts, and truss rod. Only screws I have not tightened are strap buttons, everything else has been checked.

Tuning the B string down a 1/2 step (or up a 1/2 step) makes the problem go away.
Tuning the top E string down to a B brings the problem back, but now with the high E string.
Fretting the G string at the 4th fret brings the problem back, but now with the G string.
Holding the tuner button on the E string on either side makes it go away. Nothing else works, at least so far.

That being said, best advice may be that it is in the nut somehow. I have no idea how, but will look into that next chance I get. Now that the slots are deeper, there is a chance that trimming the top of the nut down some might remove some mass and change the natural frequency of the nut. Worth a shot anyway, since only a tiny bit removed seems to have caused this problem to begin with.
Author:  Alan Carruth [ Wed Jul 04, 2018 11:15 am ]
Post subject:  Re: Strange Resonance
It's a resonance problem, almost certainly. The fact that is shows up when you play the same note on other strings shows that.

Did you take he nut out to work on it? If so, is it seated securely? The nut was the last thing you worked on before the buzz showed up, so that's the first thing to check.

Do any of the back strings off the nut resonate at that pitch? Try damping them.

Holding the two E string buttons helped. Does one help more than the other? Are there any loose parts on the tuner buttons or shafts? I once got an awful buzz at a particular pitch on a Classical due to one of the decorative sleeves on the tuner button shafts of the Schaller tuners being loose. It took several hours to find it, an thirty seconds to fix with a drop of CA. This is typical of such buzzes.
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