Out of tune frets
Hi, Just wondering why my epiphone les paul 2012 model has some out of tune frets?
I put some new strings stretch the hell out of it. adjusted the tune-o-matic to a height where the low e string measures 2mm and 1.5mm on the high E string. played the harmonic in the 12th fret and match it from the fretted 12th fret. but still some places are still out of tune like the 1-4th fret and 14-18th freth.. can anyone help me with this thanks
Your saddles probably need to be moved forward or backward. Assuming you have a good clip-on tuner, start with the worst string. Bring it to pitch. fret the same string (lightly) higher up the neck. Do not use harmonics! It's almost impossible to get at the set screws on a Tunomatic bridge with a regular screw driver while the strings are on the guitar so I use a needle nose pliers to move the saddle forward or back. Don't go crazy with this. If you got your Paul from the factory I gotta believe its pretty close and usually a quarter to half turn is all it takes. Do not use harmonics when checking the notes up the neck! Be aware too that heavy handed pickers are prone to "tuning problems" moreso than those with a lighter touch.
Yes like the previous post implied, check that your neck relief is to specification and also be sure your intonation is set with a new set of string. Sometimes a fret can be a little high making just one string on a certain fret sound off. For that get a cloth and a rubber mallet and gently tap it into place.
All the best.
The harder you pluck a string, the more sharp it will become under the existing tuning and then, as its vibration (and volume) decays, it goes flatter. So, if you are tuning by plucking the string softly and subsequently play with more string attack force, you will tend to put strings sharp at different rates from one another, based on their materials, individual diameters, and the range of diameters of the set. Therefore, try to tune the guitar strings with the relative same attack force you play with normally and this effect will be minimized.
Using harmonics to validate fret intonation isn't real world applicable if you never use them (harmonic produced tones) when playing.
What the other two posters said about you setup is true. It can be frustrating even if you have a lot of experience and it doesn't take much to make it worse.
Also, check to see if your intonation problems are situational. Are you playing notes or chords, around your frets that appear to be off, that are different finger position forms than the way you are playing elsewhere such that you hand position changes might be influencing errant note bending?
Finally, tuning is a compromise no matter what degree of perfection the intonation of your guitar has achieved. What you are playing (the key it is in, chords you use, and range of the neck you are using) may determine how you make tuning adjustments so that the lack of perfect intonation is noticed less. In some cases guitar tuning is like flying IFR (instrument flight rules)- and you have to rely entirely on the tuner. So you get the best one that you can afford and use it. If you are going to rely on your ear and harmonics for tuning and if that produces intonation problems, then using a tuner that identifies very small deviations, might be your only solution to get it to sound like you want it to when you are playing.
Good luck and best regards,