Intonation Problem

[danman]

I have an F-9 that I recently purchased. I love this instrument, except for one problem. The fourth string (A) tends to go flat. None of the other strings do this and the mandolin stays in tune quite well, but for this one string. The set up is excellant and the intonation up and down the neck is not a problem. Any suggestions?

[vkioulaphides]

This particular string may be defective. Have you tried replacing it? Also, so that I understand you correctly: Is it that just one A-string is going flat or that the entire A-course is? (i.e. BOTH A-strings)

It could also be a problem with the individual tuning-machine; or, the nut-groove for that particular string may be notchy, in which case you may want to rub some lead/graphite into it. The crucial question in that case is whether the tension on the string is equal on both sides of the nut. And, how is the saddle-groove for the trouble string?

I would start by replacing the string. All other things assumed equal, it may just be a dud.

Best of luck.

Victor

[duuuude]

Has it always been flat or could it be the result of different strings/bridge placement/ etc., etc.? If it's something new maybe try changing strings or tweaking things. Haven't noticed the problem with mine though I have noticed it's voicing changing slightly as it gets played more, for the better in my case.

[danman]

Thanks for the info. No, its just the one "a" string that goes flat. I've changed the string, but it didn't seem to help. I agree, I think it needs some tweaking like you said. I'm really happy with the tone, volume, and has the sound I'm looking for. It's been doing this since I've owned it (a couple of months).

[vkioulaphides]

Got it. I would start by smoothing/lubricating the nut-groove and (the more likely culprit) the saddle-groove for that particular string. It may be that, as the tuning-machine pulls the string upwards in the process of tuning up, the string gets caught in a rough, notchy saddle-groove. This would cause uneven tensions on the string-lengths from nut to saddle, and from saddle to tailpiece. When the string finally disengages from whatever roughness was holding it back, the string-length between saddle and nut loses tension, i.e. goes flat. Just a guess...