Weird overtone ringing

[andymue]

Hey tech gurus,

I have a McCarty (couple of years old) which is
1) a very great guitar and
2) a very resonant/lively guitar.

Now, most probably due to 2), it is a also very prone to rattling (several screws have been "rattling" loose over time) and other funny noises (e.g. pickup springs vibrating)
One of these noises currently bothers me so much that I want to do something about it:

When plucking the open D string, there is a kind of resonant ringing to the sring.
It sounds like a dissonant overtone (=unpleasant) and it it's pretty noticeable.
It's there unamplified but it's also picked up by the amp.
When playing the same note/frequency on other strings, there's nothing, so I exluced some form of sympathetic vibrations.
Also, it's only there on the open string, not when fretted.
It's most pronounced when the string is in tune. Actually, I can tune the string pretty well by ear by focusing on the ringing... :biggrin:

What I tried sofar:
New strings and stretching the string.
Dampening the strings behind the nut.
Placing a hand over all tuners to "dampen" any vibrations there.
Doing the same with the switch and pots.
Pressing the string down a bit directy behind the nut.
Wiggling the pickups a bit.

Judging from the symptoms, it would seem logical that it's the nut. But then again why is it only there if the string's in tune?

So - any advice on how I should procede to narrow it down?
Anyone experience something similar?

And finally, if nothing helps, can the "PTC Europe" (does it still exist?) take care of the problem?

Thanks!
Andy

 

[Proxmax]

did you tighten the truss rod?

 

[andymue]

Well, I set it up a couple of weeks ago...however the truss rod actually required a bit of loosening.
The phenomenon has been present before though.

I thought about a "singing" truss rod - in case that's what you suspect - but I figured if this was the case it would be frequency dependend and playing a d note on other strings should also incur the noise then, no?

 

[Twinfan]

Do you have an adjustable bridge/trem? Is it the bridge saddle?

 

[LJD]

Could the pickups be too high? (magnets pulling on the fretted string?)

 

[Bill SAS 513]

Do you have an adjustable bridge/trem? Is it the bridge saddle?

Second this...if it has a trem, try a piece of foam or soft rubber under the trem springs in the back cavity. It's amazing how a specific frequency will trigger a ringing, or some type of vibration...

 

[andymue]

Ok...after some more digging, I think I may have found the culprit:

It looks like the nut slot for the d string has been cut too low.
This in turn seems to make the string touch the first fret when the open string is played.
And for some reason, this does not manifest itself in rattle or buzz, but in an harmonic/overtone/ringing.

Raising the action to an obscene value decreases the effect and tuning higher also decreases it, so I guess that could be it.

Any ideas how I could definietly elimante other potential sources without installing a new nut?

It's a stoptail btw. and the pickups are set rather low...

 

[alantig]

Can you put something in the nut slot to raise the string a bit? Like a section of another string (maybe the G string)? It would screw with your intonation and may cause another vibration, but it should be a decent test.

 

[gush]

Take an old nut and file shaving mix with glue fill slot recut the slot.

 

[andymue]

Found this tip elsewhere: To take the nut out of the equation for a quick check, take the string out of its groove, place it on top of the nut and press it down with a finger to keep it from slipping back in the groove.

Did this and while it's more or less completely gone, there still remains a metallic "ping" like component that's still present.
Guess I'll take a shot at refilling the nut for the moment and see whether I can track down the rest. That seems to be coming more from the bridge side...

 

[andymue]

And just in case you're wondering: I did have a sane non-guitar playing person with me who also heard what I'm hearing...

 

[klarts]

Might've a loose screw somewhere.

 

[andymue]

Ok, just to bring this thread to a happy end: Bought a replacement nut and a set of nut files...replaced the nut and now the ringing is gone!
roud: