Decades ago, as a new guitar player, I remember being plagued early on by Fret Buzz.
Back then, I asked my teacher about it and his suggestion was to fret the chords as close to the frets as possible. But not every guitar I tried seemed to have this problem, so I embarked on a quest to identify the root cause.
Having researched on the web, I initially found out about the truss rod. The truss rod runs the length of the neck, and making small adjustments allows you to change the “relief” of the neck. Basically, this is the curvature of the neck. The neck needs to have a slight concave bow to it. At that time, I mistakenly thought that the truss rod was there to adjust the action. Anyway, I tried adjusting the truss rod, as I am sure many of you have, but with little or no success.
After more reading, I learnt about guitar setups. Wow, it turns out that the truss rod is only a small part of the overall setup.
A complete setup includes: Levelling and redressing frets, adjusting the truss rod for correct neck relief, filing the saddle to adjust string height at the 12th fret, and finally filing the slots in the nut to get the correct string heights at the 1st fret.
What’s really crazy is that just a few thousandths of an inch can make a huge difference to the way your guitar plays. And, trust me, if you are not a trained luthier, you will undoubtedly mess up and end up replacing saddles and/or nuts because you took too much off – I know I did!
So, my first attempts at fixing my guitars fret buzz weren’t all that successful, and then I noticed, as summer rolled around, the dreaded fret buzz seemed to subside. Maybe I was getting better at fretting the chords. Maybe my guitar teacher was right all along. But as winter returned, so too did the fret buzz.
I wasn’t really a proponent of humidifying. To be honest, I thought it was complete BS.
But then I came across one guitar manufacturer who advertised their guitars as coming complete with 2 saddles. Say what?… 2 saddles, why?… They had a taller one for the winter and shorter one for the summer… Hold on, I think what they are saying is that the string height changes seasonally. If that’s the case, there had to be reason why.
But, what could it be? After spending a lot of money, and hours working out how to set up my guitar – I decided to research wood.
So, back to researching. However, this time, instead of hitting the guitar forums, I decided to do a little research on the material properties of wood.
This was a complete eye-opener.
It turns out that wood is hygroscopic, which means it can absorb moisture from the air. When it absorbs it swells, and when it dries it shrinks. But there’s more to it than that. Wood is anisotropic, which means the amount of change is direction dependent. Changes across the grain (i.e. across the width of the guitar) are significant, whereas changes along the grain are negligible.
This is interesting. For the neck for example, the width changes with humidity, which explains why we can sometimes feel sharp fret ends in the winter; whereas the length remains the same, which is why intonation doesn’t change. But why does the height of the saddle change?
It turns out that this has to do with the construction of the top. Braces glued to the underside of the soundboard, oppose the grain of the top. The braces and the top are affected by humidity in different ways. The width of the top changes significantly, while the length of braces remains relatively constant. This creates opposing forces that cause a bending moment in the top of the guitar. In the winter the top sinks as the air dries, and in the summer the top lifts as the humidity increases. By the way, in case you’re wondering, the top of the guitar is supposed to bow out slightly – it’s not supposed to be flat
Wait a second… After all this, it turns out that humidity is the key, and surprisingly the top of the guitar is a pretty good hygrometer!
The bottom line is that if you want to keep your guitar playing the same as the day you bought it, you need to familiarize yourself with the subtle changes in action that are bought on by changes in humidity. If the action drops too low and you start to feel that dreaded fret coming on, drop in a humidifier. And when that sweet action returns, its time to stop. It’s really that simple.
On a final note, a word of caution… Too much humidity can be equally damaging. You do not need to humidify all the time – you should only humidify when your guitar needs it. Moreover, the Prolix Music Humidifiers are incredibly efficient. So much so, that they are effective even with your guitar out on a stand. If you decide to humidify while your guitar is locked in a case, be sure to monitor the humidity. When it drops below 45%, add a humidifier, and when it goes above 55% remove it.
Only humidify when your guitar needs it. Not all the time. Too much moisture can be equally damaging.
Only humidify when you need to
Drop in the humidifier when the action gets too low, and remove it when that sweet action returns.
If you keep your guitar in a case, monitor the humidity inside the sound hole. When it drops below 45% RH you will know it is time to humidify, and when it exceeds 55% RH you will know it’s time to stop.
Finally, don’t be fooled by the outdoor humidity. Relative Humidity is temperature dependent. As such, heated indoor air is often much drier than the air outside.
Feel the Action
In severe cases you can see a dry or swollen guitar just by looking at the profile. But long before you see it, you will feel it when you play.
Too much Moisture Content will cause the bridge to lift, resulting in high action making it much harder to play, while too little, will cause the bridge to sink, lowering the action and causing fret buzz.
The sound of the guitar is also another little tell-tale sign, albeit less obvious. A guitar with the right moisture content will have a fuller sound than one that is overly dry.
