String or fret buzz is a common issue for guitarists. How do you know if the amount of buzz you are getting is acceptable or if there is actually an issue with your instrument? Well, as you will see, it can actually come down to personal preference in some cases.
Defining what fret/string buzz is and is not
Fret or string buzz is a specific type of issue resulting in the string rattling against the frets of a guitar. There are several factors that can affect this and we will cover them all below. What it is not is an electronic buzz. So if the guitar is buzzing while you are not playing, this is a different issue and will be covered in another post. If your buzzing is only on open strings, you either have too little relief in the neck or your nut is cut too low. If you have an acoustic, you may have a loose brace that is rattling or a pickup wire that is vibrating inside the guitar. These issues will show if you tap the top and back of the guitar all over. eventually you will likely find the source and can react accordingly. Braces being loose is a lear sign of poor humidity control. Another thing that can cause issue is if the truss rod is rattling inside the neck. A simple gentle tap on the back of the neck can make this issue known.
Types of fret/string buzz and their causes
Incorrect relief in the neck. The guitar's neck has an adjustable rod called a truss rod. This controls the amount of bow (forward or back) that the neck has by countering string tension. Proper relief is a must for a great playing guitar. There are several ways to measure this, but a capo on the first fret while depressing the 12th is a good start. You should have around .005" of a gap between the bottom of the string and the top of the 6th fret while doing this.
Action too low? We all want our guitars to play like butter but there is a compromise. If you action is very low and you have a heavy picking hand, buzzing is in your future. Low action requires more finesse when playing, particularly with a lighter string gauge. Depending on your style, this may or may not be a problem for you.
Pickups too high? On single coil guitars (most notable the Stratocaster) pickup height plays a huge role in buzz and intonation. If the pickups are too close, the magnet may pull the string causing fret buzz. Play a note on the 12th fret and see if it is true or if it modulates. Lower pickups until the warbling sound goes away.
Frets not level. A high fret can cause all sorts of issues from fretting out to buzzing. Frets need to be level to allow clearance for the string to vibrate. We use PLEK technology to ensure perfectly level frets. The better the fret job, the lower the action and better intonation you will have. A guitar can often be measured by its fret work.
How much buzz is too much?
This is where the rubber meets the road in regards to fret buzz. Electric guitars that are setup properly to play easily and feel great will almost certainly have some amount of buzz when not going through an amp. They are made to be played plugged in and that should be factored into the question of how much is too much. We are always testing our guitar setups through an amp and listening for each note to sustain and not fret out. If it does so unplugged....that is ok. If you are heavy handed, you may need a heavier strings or higher action to make this happen. Learning to play an instrument properly is part of the fun of playing guitar. You may be surprised at how much a small change in your playing style can have in the overall performance of your capabilities as well as how your guitars sound and feel.
Ultimately, it is up to you how much buzz is acceptable but I would recommend you judge while playing through an amp. And by play, I mean actually play the guitar. Don't chase the buzz (it can drive you mad). If it doesn't surface while you are playing, I wouldn't worry about it and enjoy the guitar!