01. Why Intonate?
02. The Theory
03. The Practice
04. When do I need to intonate my guitar?
05. Floyd Roses and other floating systems
06. Tips, Tricks and other Abnormalities
01. Why Intonate?
Simply put, intonation is the ability of a guitar to play in tune at every fret, not just on an open string. The reason that this job needs doing is that your guitar may be in tune on an open string, but due to poor intonation will not play in tune on the upper frets so that amazing solo you're learning will never sound quite right. Although it can be a tricky thing to learn, once you've got the hang of it, it will stand you in good stead. Also unlike say truss rods it is not something that will damage your guitar if you do it wrong so you can practice as much as you want. Whilst I am on the subject of practice allow me to stress this point: the only way you will get the hang of this is through practice. You will be terrible at first but you will get better. It is very rare to find an acoustic where the intonation is adjustable; they usually have what is known as a compensated bridge.
02. The Theory
Every single instrument with strings including guitars, basses, cellos, mandolins, etc. is made to a particular scale length. In the case of many guitars this is 25.5 inches, the standard Strat length; however this is not the only one. Other companies use different ones but that is the most common. Each string has an ideal length. This is dependant on scale, length, pitch, action and gauge of string. Change anyone of these factors and the string will need to be "compensated" and therefore the "ideal length" will change. Also this differs from string to string. For example the ideal length for the G is shorter than that of the E, so to achieve this ideal length we must adjust the intonation by means of the saddles.
Having the string too short then the note will pitch sharp, this therefore means we must increase the length, and conversely if the string is too long the note will pitch flat. So guess what? You shorten the length, simple eh?
For those guitarists and beginners among you who know absolutely no theory or jargon, sharp (for our purposes anyway) is when the note is too high and flat is when the note is too low.
03. The Practice
Now you need to know how to actually do it, however unless you have as good an ear as a professional piano tuner (I know I sure as hell don't) you're going to need an electronic tuner. The Gospel according to power freak (GB&C forum mod) on tuners states that: The boss tuner only has an accuracy of 1 or 2 cents (I forget which!) So each adjacent string could be out by as much as 4 cents, I don't have perfect pitch but I can hear this difference! Also "chromatic" tuners aren't necessary; a regular EADGBe tuner will work. I use a "needle" type tuner because it is more sensitive to fluctuations in pitch, meaning you can get quite close to perfect intonation. A Peterson strobe would be best as it has an accuracy of 1/100th of a cent (few people can hear the difference between 1/50th of a cent! Even if they can it won't apply to the guitar because the way you pick the string and how you fret it changes the intonation ever so slightly.) However you may want to get the hang of intonating before buying an expensive tuner. Anyway, on with how to do it.
Step 1. Plug your guitar into the tuner, and starting with the low E tune it perfectly. Don't bother with the rest of the strings; we will come to them in a little while.
Step 2. Next play a harmonic at the 12th fret on that string, on your tuner it should appear as a perfect low E if you did step one right, after this play the same note but fretted. If your guitar is correctly intonated there should be absolutely no change in the pitch and the tuner will stay the same, if not well it needs adjusting.
Step 3. If it is not intonated properly and needs adjustment, take the correct size of screw driver and adjust your bridge depending on what type it is (listed in part 5). To remember which way you need to go to go in the correct direction, remember that tightening the screw will increase the length of the string (flatten the note) and loosening it will decrease (sharpen the note) the length of the string. To remember which direction to loosen/tighten the screw this little rhyme (which may sound a bit stupid) will help you: Righty Tighty, Lefty Loosey.
Step 4. Retune the string to a perfect E.
Step 5. Repeat all the above on each string (obviously at the correct pitch for each string).
Step 6. Repeat to be sure.
04. When Do I Need To Intonate My Guitar?
It's surprisingly often as it can be knocked out fairly easily. The main time is when you change your strings, as the new strings do not exert as much pull as the old set and this creates a subtle difference in the length of the neck, which needs correction. When you adjust the truss, again there will be a subtle difference that will need correcting.
Other than these times you just need to check it every few weeks to be sure it hasn't gone out as your strings stretch.
05. Different Types Of Bridges
The screws to adjust intonation on each bridge are in different places. These are the most common:
As with just about every thing else to do with these intonating it is a bit of an art, mainly because of the fact that if you move one string then it will have an effect on the others knocking them out, this means that you will have to keep having to reintonate until you get them all right good luck, it's going to take you ages. Here is a site that tells you how to do it far better than I ever could.
06. Tips, Tricks And Other Abnormalities
24 Fret Necks (submitted by Power Freak)
I have found that the intonation is more accurate (to my ear) by comparing the open string to the fretted note at the 24th fret. I don't know why this works better but it just does to me (I guess because it is an extra octave above the open string.) I found this out one day with my Steinberger, I adjusted the intonation perfectly but a few chords where just out of tune! I checked again and everything was in tune at the 12th but out of curiosity I tried the 24th frets, these were out of tune! I adjusted it to suit the 24ths and it sounded better to me! However this did move the 12th frets "out" by a cent or two but it wasn't audible to me and it made the intervals of chords more defined.
Can't Get It And Run Out Of Room For Adjustment?
The intonation is still sharp/flat and you have adjusted the saddles as far as they will go, then there is no option left but to make an adjustment by removing the saddle and moving it in the correct direction a couple of millimetres or so. If you need advice on this procedure ask in the GB&C forum we will be happy to help. However this problem is very rare and usually occurs either on very low end guitars or kit guitars. Thankfully however this is only used in the most extreme of cases usually all that is needed is a small amount of lateral thinking. In the case of Strat style bridges there is a spring on the screw that if necessary can be cut shorter or if it not long enough go out and buy a longer one you cheap git!
Tune-O-Matic bridges on the other hand are a little harder but still can be saved. If you look at each individual saddle you will notice that it is vertical on one side and sloped on the other. If say the vertical side is facing the neck and you need a longer string you can turn the saddle round this will effectively give you an extra half centimetre or so. However if you have already done this and still cannot intonate it then I'm afraid your going to have to use the first method.
XII String Guitars
This does not apply to electric XII's but the acoustic ones are often plagued by bad intonation. Usually it is sharp and the string needs lengthening. What can be done is to take a cylindrical object (such as a piece of wood but bone is best) and place it behind the saddle so that the strings clear the action. Now what you can do to adjust the intonation is to take of a little bit of dowel and recheck each time eventually it should be right, the only problem with this is it raises your action. But then again you play an acoustic XII you're going to have a good grip anyway.
There that's your lot! Sillybuuger12