Advanced Tuning
It is simple enough to tune each pair of strings by ear or each string via a tuner if we just want to get in the ballpark. Here I want to cover getting all the strings precisely in tune, which can be more daunting.
Contents
Neck Flex
The amount of flex in your guitar's neck will affect its tuning. This not only depends on your setup (truss rod tension, string gauge, tuning, bear claw spring tension), but less controllable aspects like weather. This is moreso the case for the touring musician - changing climates from say Albuquerque to New Orleans can cause wood to swell, etc. This is why it is important to play your gear on site and give it a setup adjustment several hours before the show, with a final tuning just before playing.
Floating Bridges
If you use a floating bridge, be sure that your bridges knife edges are sharp and contact the posts at a completely perpendicular angle while the bridge is at rest. Also make sure your posts don't have notches or other imperfections that can catch or otherwise prevent the bridge from easily rotating against them. This guarantees you the greatest tuning stability. Also, make sure your locking nut is tightly locked, or if you have locking tuners, your nut is well-lubricated.
Whammy bar dive bombs are notorious for throwing guitars out of tune. If the guitar is a quality instrument with a good setup, a dive bomb shouldn't be a big issue. But if you notice you have this issue with your guitar, you may have to adjust your playing away from such harsh dive bombs in a live setting (or substitute actually whammy dives with a whammy pedal).
There are devices, such as the Trem-setter, that use a double-hinge method to try to stabilize the bridge at its desired resting position. From what I hear they work as advertised; however, they also prevent you from getting a smooth whammy movement around the rest position. For this reason, I don't like them - I find they kind of defeat the purpose of having a floating bridge. But you may find them worth the compromise for live situations.
Double-Stops or Unison Bends
When you bend a string, this increases its tension. On a floating bridge, this means the string side of the bridge has additional tension relative to the bear claw springs, causing the bridge to dip as though you were pushing down slightly on the whammy bar. This makes double-stops and unison bends more difficult, as the fretted, unbent notes are now flat.
There are two possible solutions. One is to apply a slight bend to those notes, raising them up to their normal pitch. This can be difficult to get precisely, but with a little practice with a tuner, it's not as difficult as it seems.
Unison P4 to m3 d5 to P4 E---5---------------------8----------------------8-------------------- B---8b10----5-------------8b10----8--------------7b8----8------------- G-----------7b9----5--------------7b9----8--------------6b7----8------ D------------------8b10------------------8b10------------------7b8---- E---12--------------------15---------------------15------------------- B---15b17---12------------15b17---15-------------14b15--15------------ G-----------14b16--12-------------14b16--15-------------13b14--15----- D------------------15b17-----------------15b17-----------------14b15--
After making each bend, silence both notes then check each note's pitch accuracy against a tuner individually. Adjust each note by bending until both notes reach the desired pitch. Practice this exercise in additional areas of the fretboard. String tension differs across the fretboard, and the amount of bend required to be applied to each note will slightly differ as well.
The other solution is to pull up on the whammy bar slightly, raising the unbent note's pitch until it is in-tune. This is a simpler method; however, it is not useful when you have to repeatedly pick the notes - trying to hold the bar at the slightly raised position while strumming is basically impossible. However, this technique works perfectly for a sustained unison bend or double-stop. Additionally, you can use the bar to put a bit of vibrato on both notes, preventing their need to be at exactly the correct pitch.
Tuning the G and B Strings
The G and B strings are generally tuned to a M3 interval; however, there is a large degree of variance between an equal temperament M3 and a just intonation M3. The equal temperament M3 is sharp relative to the just M3. Tuning to the just M3 can make chords that use an M3 across the strings sound very harmonious - this is how Eddie van Halen tunes up, at least when the song calls for it.
On the other hand, the equal temperament m3 is flat relative to just m3. If you play mostly chords that use an m3 across these strings, or even equal amount of both m3 and M3's, equal temperament will work better.
Attack Pitch vs. Sustain Pitch
You may notice on a good tuner that tracks the pitch quickly and precisely, the initial attack seems to often have a sharper pitch than the sustained note. So, which one do you tune to? I like to tune to the attack pitch - since I play faster-paced music generally, it is more representative of what pitch I'll be at most of the time. Also, if I do sustain a note, adding vibrato gets it right back to being in-tune.
If you have a light attack and play slower, with longer sustained notes, you may want to tune to the sustain pitch instead. Or you can always just tune to between the two, which should minimize how out-of-tune you are at any moment. The difficulty there is getting each string equally in the same position between the two, so that all the strings are nicely tuned to each other.
Bending and Nut Issues
Sometimes, you'll notice that after you bend, your string's pitch is flat, even though you've thoroughly stretched out the string. The first thing to try is to draw in the nut's string grooves with a graphite pencil, getting some of the graphite in there to lubricate the nut. What sometimes happens is the string won't easily move through the nut, but when you put the tension of a bend on it, it moves but doesn't return to its previous position. This more often happens if you are initially tuned sharp and try to loosen the string to reach the desired pitch. I find that tuning up to pitch works best.
Quick Chords to Test Ear Tuning
The chords below consist completely of octaves and perfect fifths/fourths, quickly revealing if all the strings are tuned well. There should be no noticeable beating or wobble between notes - maybe a very slow, subtle swoosh if you're not too particular.
o|-|-|-|-|-| ||-|-|-|-|p| ||-|-|-|-|p| ||-|-|-|-|p| ||-|-|-|r|-| ||-|i|-|-|-| ||-|i|-|-|-| ||-|i|-|-|-| ||-|i|-|-|-| o|-|-|-|-|-| o|-|-|-|-|-| o|-|-|-|-|-|