Newbie with a ticklish problem on an Epiphone

[Richard Freeman]

Hi all,

 

Just signed up and looking for help - or at least some new ideas. I have an Epiphone PR300 dreadnought, not my favourite guitar, bought it by accident, but it's better quality than my beloved old Yamaha FG160. It's developed a clear octave harmonic when plucking the open first string, unless you pick right over the 12th fret. No similar effects playing the same E elsewhere on the neck. A local repair man (a guitar tech, not a luthier, I'll warrant) can find nothing wrong, no loose or cracked components, saddle, nut or tuner issues. Same effect through several changes of string.

 

My next plan is to swap first and second strings and see what we get. Then maybe turn the saddle round to see what happens. But someone out there may know the answer. Any ideas would be most welcome. So many thanks in advance.

[Mark Pollock]

How are the frets? Is one popped up slightly? Can you make a run up the neck without any other issues? Does it make the same sounds when other people play it?

[Richard Freeman]

I can't see any problem with the frets. Plays OK at every other fret. No-one else ever plays it, so I can't answer that one. What I forgot to say was that the harmonic seems linked to the E note. If you de-tune the string to D it doesn't ring, but is very slightly detectable playing E at the second fret.

My thinking in switching first and second around is to identify whether it is a set-up issue in first string position, or a resonance issue with the guitar itself. (As an engineer I'm full of ideas. Not being a craftsman, I'm limited in what I'm confident to do). Probably won't get to do that for a couple of weeks.

I can't remember when this started. If it had been happening from the start I wouldn't have bought the guitar. Although 15 years old now, it had really never been played by its first owner and not much by me, so it's just playing itself in. I could keep it in dodgy tunings or use a capo, but sometimes you just want to stomp around in "Farmer's Corner".

[Frank Ford]

You might want to run through the "Buzz Diagnosis" pages:

http://www.frets.com/FRETSPages/Luthier/Technique/Setup/BuzzDiagnos...

[Richard Freeman]

I've been all through the Buzz Diagnosis, but it's not really a buzz. If you pick over the 12th fret you get a pure clear tone. If you pluck over the soundhole or 5th fret or anywhere else, you get the open E and a clear octave. It's definitely the E string, still happens if you mute the other 5. Weirdest thing.

Is it something about the nut or saddle setting the string to vibrate in that mode, or is it something in the structure of the guitar resonating at that frequency and setting up the rogue harmonic?

The investigation will continue.

[LARRY KLOSE]

I have an F5 mandolin that produces a D harmonic whenever I use an electronic tuner. Unfortunately, the harmonic was a few cents off, so it never would register in tune and the tuner always detected the harmonic and not the string's fundamental. I used Frank's buzz diagnosis, which didn't produce a result. Later I happened to look at a picture of a mando with grommets between the strings to suppress harmonics above the tailpiece. Eureka! Careful testing showed no harmonics at the tailpiece but the first D string between nut and tuning post was the source of the "off" harmonic. one grommet between the tow D's and the problem was solved. Try damping that E string above the nut and see if it still sings. If it's there, the strings can be damped with rubber grommets, a leather strip woven between the strings, whatever. Other than that, I know not.

Larry

[Arthur Sweeney]

I have a Martin DXM acoustic 6 string guitar, with a harmonic problem.
I actually didn't even know what to call it until I read this post. At certain
notes, I get a string singing a note/harmonic. This happens at the
string section between the nut and the tuning post/tuners. I had never seen/
heard this before, with other guitars. I bought the guitar used, so no warranty.
But, I just placed a soft rubber strip underneath, but touching, all 6 strings,
right before the nut (between tuners and nut), and this stopped those strings
from vibrating. What causes this anyway? Is there a permanent cure?

[Tim Mace]

Either too big of a stringslot or not enough dn slope from nut to tuners?

[Gregory Hites]

I think Tim is on the right track. Since when fretting the 1st string it plays as advertised, I would file the nut slot for that string to ensure that the "land" is correct.

[Richard Freeman]

Thanks everyone for your ideas. I liked the idea that it was the string between nut and peg that was setting up the harmonic, but I've tried that out without success. So the next step is to switch a first string to second string position and see if we get the same effect.

Simple logic says that something in the set-up of the first string is upsetting the vibration mode of the open string. If there was a really powerful resonance in the guitar at 330Hz or 660Hz it would surely ring out wherever you played a high E? Or would it? I can easily make a substitute saddle to try out. Messing with the nut is getting into skilled territory. But hey, you've got to push the envelope.

[Ned Knepp]

Do you get the harmonic when the string is tuned up or down? In other words; Is the problem sound a harmonic of 330 Hz or is it the "E" string?

[Richard Freeman]

Ned, I'm pretty sure it's linked to the 330 Hz frequency. Doesn't misbehave when de-tuned to D. I expected the repair man to find something loose and was surprised when he couldn't. But it's also an open string thing - no similar effects when fretting the same note on the second string.

After trying an E string in the second string position, I'll tweak the truss rod, just in case it's loose enough to resonate.

[Ned Knepp]

Next question, though I a bit hesitate to ask it; Does anyone else hear it?

My brother had a friend that constantly complained about a "buzz" from the B string. Turns out that he was the only one who could hear it and only if he was playing.

What happens if you play an E on the B string while damping the E string?