Why do some guitars buzz and some do not?

[888guitars]

I have no real good answer to this question other than the leveling of the frets. I'm comparing two identical guitars off the shelf with same neck relief and action/string height. One may play great and the other might buzz all over the place. I check for high frets but none are really causing any noticeable issues. It must be coming down to leveling?

[Steve Conner]

Yes. When comparing string height and neck relief, it might be the same on the two guitars at the particular spot where you measured it, but that doesn't mean it's the same everywhere else on the fretboard.

From a playability point of view, the main difference between a cheap guitar and an expensive one is the time and effort that goes into levelling and dressing the frets.

[888guitars]

I agree with that. But I still have no good answer for factory guitars that are almost identical but one will buzz no matter how high the action gets? Not a real bad buzz but more of a buzz/ ringing on a lot of the frets. It's just amazing to me that one may need to be leveled quite a bit just to decrease the amount of " buzz ".

[Chuck H]

First, what Steve said. Two guitars can look to be set up the same and still not have all things created equal. Or even close. When dealing with action height adjustments things are measured in serious minutia.

There are a couple of action parameters on a guitar other than the bridge height adjustment. Good fret leveling and dress is one. Another is the neck relief. This is a really important one. After that there is the nut height. Not as big a deal as the other adjustments but still needs to be addressed to get everything just right.

There are two other things that may make a guitar seem buzzy. One is the pickups. An issue loosely called "stratitis" is the effect of excess magnetism on the strings that can cause them to buzz and/or dampen or even cause out of tune overtones. So pickup adjustment can be important also. The other things is resonance. Some guitars and/or it's pickups or both seem to have resonance such that fret buzz is accentuated. It's a real bummer when you get one of these to deal with because not much can be done to make them play really low. They're not actually more buzzy, they just sound that way. Other guitars seem to resonate in all BUT the buzzy frequencies and play strangely low because you can't really hear the buzz.

[Paleo Pete]

Some very good points made, especially by Chuck.

Also, it's not common, but I've seen loose pickup mounts cause buzzing that may be confused with fret buzz, some bridge assemblies can have loose parts, especially with cheap foreign made guitars, and you could also have problems in the tuning head area with loose parts as well. I've also seen the strat tremolo spring assemblies cause buzzing or rattling sounds.

Other possibilities...nut slots too wide, bridge saddle slots too wide, loose nut (yes I've seen that)...with an acoustic you can also find loose inside support struts that will buzz and loose or improperly set bridges and saddles that can cause problems. I had to set up one guitar several years ago that had pickups so close to the strings they were buzzing...sounded nasty too...

Anyway my first guess, without being able to look it over close, is fret dress. Second is not enough back bow, which means truss rod adjustment. And once again once I say truss rod I have to also point out that the truss rod DOES NOT have a major affect on action or intonation. That is an all too common myth, the truss rod only allows the neck to have a slight bow away from the strings in the middle to compensate for the wider vibrational pattern of the strings in the middle of the neck. The affect on action is extremely minimal, you will not notice it by playing it. No affect on intonation at all. With a fairly high action, like I use since I play a lot of slide, you can keep the neck almost entirely straight with no problems, with low action back bow gets more critical because the strings will buzz on the frets especially in the middle of the neck, due to the wider vibrational pattern there. I keep mine set with the proper back bow, and I can't tell the difference if I reset it straight.