I'm thinking I should switch to a slightly heavier set of strings for a better "rounded" tone, especially on the lower strings.

Currently I use Martin Phosphor Bronze .12-.54 gauge, the one I'm eyeing is a D'Addario .13-.56.

My guitar is a OM (000) style acoustic, 25.5" scale with fixed bridge; it has a mahogany neck, bone nut and compensated bone saddle.

So, if I make the switch from .12-.54 to .13-.56 gauge strings, will I have to make a truss rod adjustment, or nut and saddle change, or any other changes?


3 Answers 3


Your guitar will tell you the answer. It will respond with action changes, and those may be within your realm of "normal", or they may exceed that and become undesired.

With the lighter (original) strings installed, did you measure the action in order to quantitatively assess the change in tension? Do you have a new measure with the heavier strings for comparison? Does the guitar play satisfactorily?

Ultimately, a truss rod adjustment may suffice, if necessary. Remember to adjust it in small increments, then wait for things to "settle". This time of year, you may also need truss rod tweaks for humidity, depending upon how you store your instrument. And if you're not comfortable performing the changes yourself, take it to your local luthier or setup tech.

If you were satisfied with the setup before the string change, I do not expect that any saddle or bridge adjustments would be required. Enjoy yourself!

  • I haven't actually made the switch yet. As you suggest, I think I should first change the strings and experiment a bit. I switch between standard tuning and a half step down often, I'm guessing the heavier gauge will like the latter. Truss rod adjustment I can do if it becomes necessary, but I'm kindof concerned if it may need a nut or saddle change because there aren't many luthiers around here that I know of. Thanks for the answer, I'll leave the question open though if anyone wants to add. Cheers! Commented Dec 20, 2016 at 13:20
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    IME the truss rod adjustment is guaranteed. The nut and saddle will probably be fine as long as they are not cut too narrow. Commented Dec 20, 2016 at 13:29
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    @ToddWilcox is correct about the nut slots and saddles. At first blush, I figured it is only a 0.001" - 0.002" change. Then I recalled that I ordered my nut slots files specifically for the 0.010" - 0.046" gauges that I typically use. So, depending upon the exactness of the slots, if the strings act "sticky" during tuning changes, then double-check the nut slots and saddles with appropriately sized files.
    – Kirk A
    Commented Dec 20, 2016 at 17:18
  • I've often changed to and from .008s and .010s, on lots of different guitars, with nothing adverse happening in the nut slots. It's not that important, I feel.
    – Tim
    Commented Dec 27, 2016 at 12:11

The average extra tension, given the same material strings, is around 5% or less. This shouldn't make a lot of difference to the neck. Obviously, after they've settled for a few days is when the evidence will show - or not. Intonation wise, again, the guitar will most likely shrug its shoulders.Some guitars are like that! Others may be a little fussy.I think if you tuned up just under a semitone,(with the existing strings), that would give a fair idea of what the new strings could feel like. A proper calculation would give more exact variations, but this is rule of thumb.

  • Troll downvoter again! Unable to comment due to lack of something?
    – Tim
    Commented Dec 27, 2016 at 12:09

as these guys have said, the combination of woods, existing setup (even scale-length) and environmental factors will ultimately determine whether setting up is needed of not. ive got a couple of guitars i NEVER need to setup, and another couple that need setting up almost continually.

in answer to your question- i dont think the tension is going to go up considerably, if youve got a truss rod, it might want aq quarter turn or two (done over a day or two) to counteract the tension increase. otherwise you may lower the bridge a tad, but i dont think its going to be noticably "worse" to play.

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