Wednesday, June 10, 2009

Changing string gauge

The follow question was posed to me:

So…my new Carvin came with:

D'Addario EXP phosphor bronze light acoustic
..012, .016, .024, .032, .042, .052

I tried putting on my Martin .010 - .047 and had hideous fret buzzing…do I need a new saddle? Or neck adjustment?

Answer:

Yeah, with the 0.12 set you had 163.11 lbs of string tension total.
With the new set 0.10's of Martin's your total string tension is approximately 135.39 lbs. A difference of -27.72 lbs.
This will make the neck flatter and reduce the amount of forward pitch. In my opinion there should always be some bow to the neck. What I mean is: If you fret the first fret of any string and simultaneously fret the 17 fret of the same string - You should see a gap at the 5th fret that is almost equal to the width of the string being fretted itself between the top of the fret and bottom of the string in question. What you have done is inadvertently reduced that gap by decreasing the tension of the string by way of decrease string girth and mass.
Solution: You must compensate the loss of mass by inducing more bow by tightening the truss rod. Without the benefit of examining the guitar myself, I would recommend that you tighten the truss rod carefully in a clockwise motion (facing the guitar neck with the body of the guitar furthest from your torso). I would start by adjusting the rod by 1/4 rotation clockwise then re tune your guitar and test your adjustments. Repeat until you've accomplished reduced string buzz but beware of over tightening the truss rod for if you break it off inside the guitar then the repair will be costly and maybe not worth it.
It is my experience that acoustic guitars are very sensitive to humidity and this very problem could arise solely due to climatic change. Once set also be aware that the guitar will take about 24 hours before it settles according to my experience (the climate is benign here and relative humidity is yearly 40.0 rh and temperature roughly 70 º F.)
I use a gauge to measure before adjusting and real time. It's costly and you can do as well with patience and care. Lastly, you should make note of your gauge change and to save yourself undue stress - stick to the same gauge as much as possible. Indeed, changing gauge will also effect your intonation. However, that effect is also dependant on your ability to hear perfect pitch as you ascend or descend on the fret board.
Sorry but a short question doesn't necessarily correlate a short answer.
Regards, Scott


1 comment:

James said...

Hey thanks! You saved the day!

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