what exactly cause fret buzz?

[therex]

the title saids it
i am having some fret buzz in the high frets but i need to know whant causes it, i know it could be action or the neck but i adjusted that already.
so what exactly cause fret buzz? is it that the strings hits the next frets while vibrating or something like that?

[Al Heeley]

Yes, normally a higher fret that sits a bit proud of the one just in front of your finger, catching the string at the lower point of its vibration.
If you are happy that:
a) the action is good and
b)the neck is true and
c) the nut is cut well and
d) the bridge saddles are at a good height
then the offending fret can be found and levelled, then recrowned. I use a 6 inch steel rule along the frets to rock it back and forth in search of the high spots, then attack them gently with a fine file, wet-n-dry paper, finish with a crowning and a polish.
If you are happy that all your frets are level, then you may have to live with a slightly higher bridge saddle and higher action to get round the buzz.
But basses are notorious at buzzing when you play them unamplified, as they are so quiet there is a tendency to hit the strings far harder than when in an amplified gig situation. Does the fret buzz still bug you when amplified?

[therex]

Originally Posted by Al Heeley

Yes, normally a higher fret that sits a bit proud of the one just in front of your finger, catching the string at the lower point of its vibration.
If you are happy that:
a) the action is good and
b)the neck is true and
c) the nut is cut well and
d) the bridge saddles are at a good height
then the offending fret can be found and levelled, then recrowned. I use a 6 inch steel rule along the frets to rock it back and forth in search of the high spots, then attack them gently with a fine file, wet-n-dry paper, finish with a crowning and a polish.
If you are happy that all your frets are level, then you may have to live with a slightly higher bridge saddle and higher action to get round the buzz.
But basses are notorious at buzzing when you play them unamplified, as they are so quiet there is a tendency to hit the strings far harder than when in an amplified gig situation. Does the fret buzz still bug you when amplified?

yes
i have just readjusted the neck and it helped with the fret buzz but there is a lot(i can barely hear the note) of buzz in the 15 to 17th fret
when amplified the note can be recognised but i can still hear the buzz(is really extreme buzz)

[dbcandle]

You could have bad fretwork or a "swollen tongue" (if bolt-on), where the wood at the higher frets is swollen due to the screws/bolts holding it to the neck are too tight (or moisture got in). I'm not a tech, but I think "swollen tongue" is more a problem slightly higher on the neck than you are reporting, so I'd suspect fretwork, but I'm not sure.

I'm assuming you read the stickies at the top of this forum and the buzzing is *only* on the very high frets.

You may care to post measurements for your a) relief and b) string-height. On my MIM Jazz, I can't get below 5/64ths on the treble side or 7/64ths on the bass side without buzz, rather consistenly accross the neck. Obviously, if you have a vigourous playing style, you'll need higher action than you otherwise would.