String tension question

[thistle3585]

As strings age and stretch does the string tension increase to bring them to pitch? For the second time, in a year, my mandolin has started buzzing around the 6th to 8th frets when I finger it in that range. The strings are clearly vibrating against surrounding frets when fretted. It started happening out of the blue two days ago. I pushed the strings to the board at the nut and last fret and there is clearly a bow in the middle of the fingerboard. If I release the string tension on the neck it goes away. I thought I had adjusted this out about 7 months ago, but here we are again. I wonder if the J-74's are too much for it or that I just hadn't adjusted the trussrod well enough. I can't imagine it to be humidity or temperature related either. I just wanted some opinions before I start work on it. BTW, it is the first A5 that I have built.

[Chris Baird]

Why do you factor out humidity? Tis the season for buzzes.

[thistle3585]

I guess I shouldn't factor out humidity, but I haven't noticed any significant changes in the last couple weeks. My thought is if it were humidity then it would have happened several weeks ago when we kicked on the furnace. Is humidity going to affect the neck that much? Raising the bridge really doesn't help much because it raises the action too much on either end of the fingerboard. I'll try and keep an eye on the humidity and see if that will bring it out of it.

[Chris Baird]

Wood is always changing and sometimes it takes awhile for climatic changes to affect an instrument. Sounds like it just needs a tune-up on the set-up. Such a need is certainly not uncommon as you can't expect a wooden instrument to stay the same forever.

[judith]

Chris is right - tis the season for buzzes. I find my instruments change a lot in the winter, especially with the dry heat in our house. I always have to raise the action a little. I don't know about the "bow" in the neck - chris is the builder - but I know about winter buzzes. I find it difficult to maintain the proper humidity...I use a dampit or a planet waves black plastic thingy and leave it in the case for a week or so, and then out of the case, for a week or so. Hope your action isn't TOO bad. Judith

[Paul Hostetter]

Simple answer to the very first question: no. The tension necessary to get any string to a given pitch is constant regardless of age.

Re: humidity: don't spot humidify the interior of your mandolin for brief periods, humidify the entire environment you - and it - live in. If you see a bit of condensation on the insides of your windows, that's about right. If the windows are clear, it's too dry. Those cheap vaporizers from the drugstore are great for this. It's good for you, too, not just your instruments.