how to fix fret buzz

So. You've got a guitar that you love. It looks, feels, and sounds great... but, some (or all) of your strings are buzzing against the frets and it's driving you nuts. Let's take a look at some of the common causes of fret buzz and the appropriate ways to address each one. By the way, this is just an overview and not an in-depth tutorial.

Let's first define what "fret buzz" is in the first place. Fret buzz is the annoying sound caused by a guitar string rattling/buzzing against a fret wire when the guitar string is being plucked or played. There are three common causes of fret buzz:

Frets are not level with each other (some are taller, some are shorter)
String Action is too low
Neck does not have enough "relief" (neck is too straight, or bowing backwards)

Note: I did not include technique as a cause of fret buzz, but it is worth mentioning because, at a certain point, the cause of fret buzz is the player and not the guitar. Basically, if the player attacks the string too aggressively on a perfectly fine guitar, fret buzz will still occur.

#1 - Frets are not level with each other

The rule is the frets on your guitar are supposed to be level with each other. That means they should all be the same height. There is an exception to this rule (upper fret "fall-away"), but I will not be getting in to that here. When the frets are not level with each other, that means some of the frets are shorter and some of the frets are taller. It's the tall frets that the string physically comes in to contact with, resulting in fret buzz. The string does not buzz against the low frets. Pictures will probably help illustrate what I'm saying.

Let's start with what we want to see:

Fret #1 and Fret #2 are the same height.
The gray line is the guitar string. The guitar string is being fretted at the first fret (by an invisible finger).

Great. The frets are exactly the same height off the fretboard, which results in there being a space between the top of Fret #2 and the bottom of the guitar string. Because a guitar string vibrates when plucked, there needs to be enough space between itself and the fret to allow for that vibration to occur without the two coming in to contact with each other.

Here's what we don't want to see:

Uneven Frets
The gray line is the guitar string. The guitar string is being fretted at the first fret (by an invisible finger).

Uh oh. Fret #2 is taller than Fret #1, which results in there not being enough space between the top of Fret #2 and the bottom of the guitar string. That means the guitar string will rattle/buzz against Fret #2 every time the guitar is fretted and played at Fret #1. In extreme cases, there will be no gap at all (they're touching) between Fret #2 and the guitar string, and the result is a dead fret... the guitar can't even produce the note!

Let's see what happens with low frets:

Fret #2 is shorter than Fret #1
The gray line is the guitar string. The guitar string is being fretted at the first fret (by an invisible finger).

Remember how I mentioned the string doesn't actually buzz against the low frets? We should be able to see clearly as to why. Fret #2 is so low that it actually increases the space between itself and the bottom of the guitar string. That means the string could be fretted and played rather aggressively at the first fret and still not buzz because there's so much space for the string to vibrate... But, what if we want to play a half step up (at the second fret)? Because Fret #2 is so low, we can almost be certain that Fret #3 would be taller and so the problem of fret buzz is still present; it just got shifted up the neck. Drat!

So, that's why it's super important all the frets on a guitar are the same height, or level, with each other. At Halo, every instrument is put through a full fret leveling process and it's performed by one of our professional guitar technicians in Cupertino, California. This allows us to set up our guitars with very low string action while still being able to offer buzz-free playing.

How to fix fret buzz caused by uneven fret heights: Perform a full fret leveling procedure. This is a multi-step process and can take a professional between 1-2 hours depending on the condition of the fretboard and the frets themselves.

#2 - String action is too low

Let's define "string action". String action is the height of the guitar string measured at a specific fret. It's not enough to just provide a string action measurement by itself; it's necessary to know the string action measurement and the fret at which that measurement was taken. It's common to take string action measurements at the first fret, twelfth fret, and seventeenth fret. Different players will have different preferences for their string action. Some players prefer relatively high action, while others prefer very low (aka "slammed") action.

There is a threshold, though, to how low the string action can be set before it starts to create problems. String action is difficult to measure with standard rulers, so we recommend this String Action Gauge. We have several of these gauges in our shop and they're very useful for setting up each individual string to the desired action. We like to take our action measurements at the seventeenth fret for all our electric guitars. Our string action threshold is around 0.050" for the treble strings (GBE), and around 0.080 for the bass strings (EAD). Setting the action lower than this is not advisable as it will likely result in fret buzz. Here's a link to more info on how to use that String Action Gauge: http://www.stewmac.com/Luthier_Tools/Types_of_Tools/Straightedges/String_Action_Gauge.html

How to fix fret buzz caused by low string action: Loosen the strings a bit to relieve tension, then increase the string action by making adjustments at the string saddles (located on the bridge).

#3 - Neck does not have enough relief

A guitar neck is supposed to be close to perfectly straight, but not quite. Assuming the guitar is strung and tuned to pitch, it should have a slight dip in the middle (around the 8th fret). That dip is measurable and we call it "neck relief". If a neck has a dip in the middle, we can refer to that neck as having "forward bow". If a neck has no dip at all, but rather a hump, then we can refer to that neck as having "back bow". Back bow is always bad. Back bow means there is not enough relief in the neck and it often causes all or most of the open strings to buzz on the first fret.

Neck Relief (image from http://customguitarprojects.co.uk/)

When you experience all or most of the strings buzzing when played open, then it is likely the neck is back bowed (there's not enough relief). The strings are buzzing against the first fret. The fix is simple: increase the amount of relief in the neck by loosening the truss rod.

Halo instruments are equipped with two-way adjustable truss rods. On the majority of our guitars, the truss rod is adjusted at the headstock side with a 4mm hex wrench, which is always supplied with our guitars. There are guitar necks out there that can only be adjusted in one direction, and still other guitar necks that can't be adjusted all. The two-way adjustability is handy because we can increase and decrease neck relief depending on the condition of the neck.

To roughly measure the amount of relief in the neck, we could use the string as a straight edge by pressing and holding down on the first and last fret of the 4^th string, and then looking very closely to see if there is a gap between the bottom of the 4^th string and the top of the 8^th fret wire. This is a very imprecise method, but it can be helpful if you have nothing else better. If there is no gap (the string is touching the fret wire), then the neck is probably back-bowed. If there is a huge gap (say, 0.5mm or more), then the neck is probably forward-bowed. With the guitar strung and tuned to pitch, truss rod adjustments can be made until only a very small gap can be seen and you'll probably be able to eliminate the fret buzz. The gap should be smaller than the thickness of a regular High E string.

There are significantly better and more precise ways to measure relief. Straight edges and relief gauges are available at Stewart MacDonald, but the average guitar player probably doesn't want to purchase those tools for this purpose, and that's why I described the method above. Halo does not use the above method in setting neck relief. We always use straight edges and gauges.

By the way, if you've ever seen somebody pick up a guitar (to inspect it) and look down the neck while squinting and moving their head side to side a bit... they were "sighting" the neck in order to check the amount of relief in it. That is another quick and easy way to determine if the neck has too little, too much, or approximately the right amount of relief. Learning to sight a neck is also helpful in that it enables you to make the necessary truss rod adjustment without any fancy tools.

For neck relief, it would be really nice if we could just set it and forget it. But, the amount of relief in a guitar neck will definitely change over time, and it is due to a variety of reasons such as:

changes in temperature
changes in humidity
changes in elevation
changes in tuning
changes in string gauge

Well, there you have it. Three common causes for fret buzz: (1) uneven frets (2) excessively low string action, and (3) a back bowed neck. Just one of these problems is enough to cause fret buzz, but often times a guitar has a combination of these three problems all at once. Halo instruments are always shipped with level frets and proper string action, so if you're getting any fret buzz on your new Halo guitar, you only need to make a simple truss rod adjustment!