Tuning Problems

  To begin with, the guitar is not a perfect instrument, and tuning must always be tempered, meaning you have to compromise. Even when tuned with an electronic tuner, there will be at least one note in one chord that doesn't sound quite right, and if you tune the note perfectly for that chord (not usually a good idea), other chords will sound worse. I finally accepted this as fact, figured out which notes and chords really bothered me, (fortunately for me, I guess, I only use a few chord forms) and learned to temper the tuning in a way that worked for me and my style.

  On guitars without vibrato bars, there is usually not much to keep them from staying in tune. Start with a few basic assumptions: the strings are fairly new and still in good condition (old, rusted and/or crusty strings won't play in tune very well); you ALWAYS tune UP to pitch, and if you are already sharp, tune the string a little bit flat, stretch it slightly, and THEN tune up to pitch. (If the string is sharp and you tune it down exactly to pitch, there will be a tiny bit of slack left in the string between the nut and the tuners, and when you start to play, it will pull through the nut and go flat).
  If you tune the open strings with an electronic tuner and your first position chords are still badly out of tune, or if you hear a "tink"ing sound when you tune, and the strings seem to go sharp by themselves while you play, the slots in the nut probably need to be re-cut.
  If the first-position chords are in tune, but chords played up the neck are not, a bridge intonation adjustment is probably needed (assuming, again, that the strings are good).

  Guitars with vibrato bars can drive you crazy (I've smashed a couple, myself!), but there are a couple of things I've found out that helped me keep them in tune a little better.
  My experience with a "Floyd Rose"- style bridge is that, when it has been used for a while, the bridge can develop two natural resting positions: the position it stops in after you push the bar down and let it back up slowly against your hand; and the position it stops in after you pull the bar up and let it back down slowly against your hand. The guitar can only be in tune in one of those 2 positions, and if the bridge returns to the wrong one, the guitar will be out of tune.
  The tuning routine I use is, (while using an electronic tuner and always tuning UP to pitch), to leave the string a little bit flat, and then push the bar all the way down to the body and let it come back up gently (under it's own power) against my hand. After "working the bar" like that, I check the tuner again; the string will usually have sharpened a little. If it went too sharp, I tune the string down a little more, "work the bar"again to stabilize it, and repeat the process. After tuning all the strings this way, "working the bar" after every little tuning adjustment, the guitar should stay in tune better. If it does go out of tune while you are playing, before you start re-tuning, try pushing the bar all the way down and letting it ease back up against your hand ("working the bar"- got it?); once you have this system down, the guitar should usually come back reasonably in tune by itself, without having to touch the tuners very often.

  It's also very important on Floyd Rose trems that the hinge (for the fine-tuner) on each bridge saddle is kept lubricated and moves freely. If these get tight, the fine tuning doesn't work smoothly, and you'll have tuning problems.
  To test the hinge, with the strings tuned up push the long bolt (that's used to tighten the end of the string into the bridge) downward (towards the body) and then let it go. It should snap sharply back into place against the fine-tuning screw. If it doesn't, you need to clean the hinge.

  A common problem with Strats, sometimes called "Strat-itis", occurs when the pickups are raised too close to the strings. This can cause single fretted notes to sound almost doubled, and impossibly out of tune, especially on the low "E" and "A" strings. This is caused by magnetic interference from the pickup pole pieces, and is easily fixed by slightly lowering the offending pickups (usually the neck- or middle- pickup).