Saturday, June 13, 2009

It's that time of year again

Truss rod adjustment time. It comes around twice a year in the Spring and Fall. Now the rainy season has been upon us for a few weeks the effects are starting to appear. I first noticed my long scale bass buzzing around the lower frets. Next, the Firebird was buzzing on the open D string and first fret. No coincidence as these two have the longest, slimmest necks of all my instruments. I haven't played either for a little while so the change seemed to come on somewhat dramatically. Huh?! WTF? Oh right... it's been raining for two weeks. I learned to recognized this effect early on in my guitar playing career, but it is still a pain in the butt if you pick up a guitar to play and there's a bzzzzz that wasn't there a few days ago.

The reason for this is humidity of course. As it becomes consistently higher like it does near the Jersey shore (oppressively humid in the warm season), the wood in the neck and fingerboard begins to swell giving the neck a slight backward bow causing the strings to lengthen and lower. On my instruments with beefier 50's style necks like the SG Special and Melody Maker, the effect is less immediate. Even though my old '68 SG has quite a narrow neck, it is not as shallow as the slim 60's profile of the Firebird, so it may not need adjustment for a while. Haven't played the 335 in a week or so, but I'm sure it will be affected soon being a slim 60's profile.

To the seasoned player all this surely comes as no surprise, but for the less experienced, you may just pick up your axe one day and go "huh? It played fine yesterday, wtf?" If your action is high you may never experience string buzzing, but it will affect your intonation regardless of the action. Since Gibson guitars have mahogany necks they may be more sensitive to humidity than hard maple necks which have tighter grain, thwarting humidity more effectively (I would imagine, you'd have to ask a Fender player).

For some, making a truss rod adjustment themselves is unthinkable and prefer to take their axe to a pro for an adjustment. It really isn't that difficult! If you're even slightly serious about playing, you should learn this stuff. Also, when the truss rod is adjusted, quite often you'll need to tweak your bridge height and intonation as well. Although you would think in theory if the neck is tweaked back into position, the rest would fall back into place, that's not always the case. These adjustments are simple as well once you know how to do them. I would love to have a full time guitar tech to deal with this stuff, but not being the case I have always done all my own guitar work.

To offer some advice from my experience, just be careful and go slowly. It often takes 12 to 24 hours for a truss rod tweak to take effect, so don't over do it! I usually find a quarter turn of the nut is enough, but on newer guitars which seem more susceptible to humidity changes, you may need a full half turn. But do it in two stages to be sure you don't go too far... quarter turn looser, maybe another quarter turn the next day if need be.

If you are traveling or use your guitar in a lot of different places, sometimes you need to adjust more often. For years I just left the truss rod cover off of my SG and tweaked it as often as needed... but that is ugly I suppose and I've become more conscious of that in these times of vintage guitars and their 'purity' lol... be careful not to lose the little cover screws, they're a pain in the butt to find on the carpet and a hassle to get proper replacements.

On a side note, Gibson guitars are a joy to adjust with a full size nut on the truss rod end. Asian imports (and Fenders) have allen key adjustments which are a royal pain... firstly, just finding the proper size allen wrench is a challenge (since different brands use different sizes) and, they are very easy to strip out. If your truss rod nut is really tight, chances are a steel wrench will easily strip out the soft brass bolt rendering it useless. Nightmare! Gibson TR nuts have greater surface area for a socket to grasp, sockets are more readily available in the average tool kit than metric allen keys (tho' you should carry one with your guitar), so yet another reason for my Gibson preference (Orville Gibson invented the truss rod FYI).

To wrap this up, obviously in the Fall the opposite is true. As things dry out and your guitars are living in a drier, heated environment, the wood shrinks and you need to tighten the truss rod as the neck begins its bow forward. The symptoms of this are higher action and the intonation going out. Back to tweaking, I have recordings to make!

Remember: righty tighty (Fall), lefty loosey (Spring)