Is buzz bad?
Most of the time.
However, if you’ve got a low action on your electric guitar or bass and you tell me you can hear a buzz when you play it unamplified, I’m going to ask you if that buzz can be heard when you play it through the amp, in a normal setting.
Buzzes on electric instruments that can’t be heard through the amp are often the price of that low action you like. In an ideal world, it wouldn’t be there but it’s not an ideal world (see note above on harps). If you want to play your electric guitar unamplified, it might need to be set up differently. Remember that there’s a reason most acoustic instruments are not set up with actions as low as their electric cousins.
Is your action appropriate for your style of playing? We’ve talked about this before—if you’re a hard player, you can’t expect to play with the same action as a really light picker. Bigger string vibrations need more room to move and a higher action is the answer.
Consider string gauge
Super light stings wobble about more on a particular instrument. A heavier gauge might give you a cleaner result. Playing the heaviest strings you’re comfortable with is always good advice.
The elephant in the room: technique
Ooooh. This is the difficult bit.
I’m (very, very) far from being the best player in the world. However, I’ve worked on these things enough that, at least, I’m pretty good when it comes to fingering/fretting notes cleanly. There have been times when I’ll play a guitar that someone’s brought in for buzzing problems and it’ll play just fine.
That’s tricky. Nobody likes to think something might be their fault (I certainly don’t) and nobody wants to be the guy to tell someone that it’s their fault (I certainly don’t). But sometimes it is.
Fingering position and pressure are likely culprits. You want to be right behind the fret with a firm enough pressure to ensure good string-contact with the fret. If chords are buzzing, play the same notes individually—is the buzz still there? Sorry that I’m teaching grandmas to suck eggs here. However, if someone else can cleanly play your buzzing guitar, you might need to consider adjusting your technique or your expectations for your setup.
On to Hardware…
Of course, there are hardware problems that can cause fret buzz. A couple of the more common:
Hardware issues: High/Low Frets
For a guitar to play cleanly, each fret should be neither higher or lower than its neighbours. If a fret is high, playing notes behind it may cause the string to vibrate off that fret. If you’ve a low fret, then the fret directly in front of it is (relatively speaking) a high fret.
High or low frets can be caused by poor fret installation and levelling. It’s also possible for frets to loosen and to sneak up out of the fretboard over time.
If your guitar buzzes in one or a few small areas but plays cleanly elsewhere, high or low frets may be the reason. For instance, if you’re playing each note up the board and all play cleanly until, say, 9th fret. The 10th has a little buzz and the 11th sounds awful but the 12th plays cleanly again. You might have a high 12th fret.
It’s not always so cut and dry as this, of course, and it can be useful to use a short ruler to try ‘rock’ across a few frets. You can buy a ‘fret rocker’ (which has a number of different-length sides to fit across differently spaced frets) from Stew Mac or eBay, or you can cut a 6" steel rule into different lengths. If you span three frets and your tool ‘rocks’, one of those frets is higher or lower than its pals.
Hardware issues: Nut Slots
If you get a buzz when you play an open string, there’s a good chance the string slot in the nut is too low. It’s also possible the you need a little more relief or your first fret is too high. Odds are good it’s the nut, though.
Hardware Issues: Relief
Incorrectly set relief (the bow your neck pulls into under string tension) can lead to fret buzz.
At a high level, too much relief can be a cause of some buzz higher up the neck. Too little relief might cause some buzz all over if you don't play lightly. A back-bowed neck will generally buzz in the lower positions and play more cleanly higher up.
This is all very general. If you haven’t downloaded your copy of Truss Rods Made Easy, pop off and do so. You’ll find more information on relief issues in there.
Hardware Issues: Humps and Bumps
The neck itself can sometimes be less than level. Humps and warps can happen. The result is that some sections are higher than their neighbours and that has to be addressed. A fret level or fingerboard level/refret is often the answer.
The bottom line
Potential hardware issues aside, a good setup for you may well be the result of some compromises. You might have to play with a lighter touch if you want a low action. Or, you might need to play a higher action to accommodate your style. You might need to live with some unamplified buzz.
Before you ask your repair person to lower your action, really, really think about it.
The most perfect, flawless, fret-job in the world will buzz if the setup isn’t right for the player’s style and technique. Be realistic about what’s right for you and don’t worry too much about unamplified buzz.
Or buy a harp.