Checking and Adjusting Electric Guitar Intonation
Intonation- Having an instrument "in tune" throughout the scale is the goal of every player and luthier. Different string gauges, scale lengths, set ups, fret sizes, playing techniques and other variables can effect your instruments intonation. While it is true that there is a certain amount of compromise on equal tempered instruments, my goal is to have the best possible intonation.
Poor intonation is best described by saying that the notes of some chords sound in tune while others seem far from it. This condition is present even though the instruments individual strings are said to be in "perfect tune". Welcome to the world of the equal tempered scale and the quest for perfect intonation!
To help explain this occurrence it's important to realize that the differences in the strings mass, tension, length and fretting stretch all effect the notes pitch and your intonation. There are also other factors that can affect the instruments ability to play in tune which I'll mention later.
Scale Length and String Length The strings scale length* begins at the nut and ends at the saddle. If you look at the saddles on your guitar or bass you will quickly realize that they do not sit parallel with the last fret (with the exception of some classical guitars) as they been adjusted to alter the strings length and intonate the instrument. Some additional string length is added to the actual scale length in order to off set the sharpening of the note which occurs when the string is stretched while being fretted.
*Literal scale length can be determined by measuring the distance from the nut end of the fingerboard to the center of the 12th fret and doubling it. Compensation is added to the scale length, measuring from the nut to the saddle would actually give you a figure slightly longer than your instruments "scale length".
Factors That Can Cause Poor Intonation
Incorrect positioning of the saddles This error renders the strings either too long causing intonation to be flat or too short causing the instrument to play sharp.
High action An instrument with high action will of course cause the string to be stretched further before contacting the fret, this stretching sharpens the note slightly. High action at the nut is particularly troublesome as chords played in the 1st to 3rd position can sound terribly out of tune.
Excessive Relief The strings distance to the fret can be dramatically increased on necks that have far too much relief (dip or bow towards the center). More on relief
Pickups Are Too Close to the Strings - If the pickups on your electric guitar are adjusted too close to the strings the magnetic pull can cause sharpness. Correct this before intonating the instrument. A good rule of thumb is about 3/32" between the pole and the bottom of the string when the string is fretted on the last fret.
Worn Out Strings/Defective String Replace the strings on your instrument before intonating it.
A Loose or Moving Saddle , A major problem with some of the cheaper bridges is excess play where the screw is threaded into the saddle. A good deal of play here means the saddle can move itself around requiring constant readjustment. You may wish to read my article on TonePro® bridges as an example.
A Worn saddle Wear and tear can change the contact point of the saddles crown. The wear may lengthen or shorten the string slightly.
Worn Frets Frets that are badly grooved or have flat crowns can also throw off intonation. As the point of contact on the crown of the fret changes so does the strings length. Frets must be leveled and dressed to remove the grooves or replaced if necessary.
High Frets Fret height will also effect intonation...instruments with truly tall fret wire will play incredibly sharp if the string is fretted hard. To see for yourself what effect your fretting pressure has on the instruments tune watch the pitch of the note on our tuner when fretting with different pressure.
Technique Well this isn't actually a defect, it's a "style". Some players have a rather powerful fretting technique in which they place excessive pressure on the strings when fretting and if the instrument in hand happens to have fairly tall frets this is more than enough to mess with your intonation. Some players may actually have a tendency to bend a string sharp when fretting.
Different Tunings Most professional musicians will have different instruments for different tunings. By tuning your instrument a half step down you have changed the strings tension and will normally effect the intonation.
Far Less Common Issues
A Mathematical Error If the bridge/tremolo itself has not been positioned in the correct spot on the top you may find that the saddles have been adjusted to their maximum length without reaching the required adjustment. This is very rare, most likely to be found on a no-name, home-made instrument or something with a mis-matched neck/scale length.
Adjusting Your Electric Guitars Intonation
| QUICK CHECK: Tune your instrument to pitch and fret each string naturally at the 12th fret. This note is one octave higher than the open note and should be in tune (neither flat or sharp). |
* Make any and all adjustments to your instruments action prior to adjusting its intonation. Changes in string height or string gauge can effect your intonation. Intonating your instrument should be the last step in your set up.
* Put on a new set of strings, stretch them out and tune to pitch. Because the size of the string effects intonation you will need to re-adjust intonation if you change string gauges.
* Use a good quality electronic tuner. Tuners which have an accuracy of 1/10th of a cent are extremely accurate, tuners which have an accuracy of ± 2 cents are far less reliable and would be useless if you are using off-set tunings like the Buzz Feiten System requires.
* Check each strings tuning at the 12th fret, this note should be neither sharp nor flat, if it is, you will need to adjust the saddle to change the strings length.
Adjusting your intonation- If, after tuning the string to pitch it plays sharp at the 12th fret then you will need to increase the strings length by moving its saddle further from the fingerboard. If the note is flat, the string must be shortened by moving the saddle closer to the fingerboard.
Make sure to retune after each adjustment, recheck and adjust if necessary.
12th Fret Plays Sharp - move the saddle away from the fingerboard
12th Fret Plays Flat - move the saddle closer to the fingerboard
More Adjustments
Nut Compensation - As I have already explained, fretting a string stretches and sharpens it. If no additional string length (compensation) were added to an instruments actual scale length the instrument would play sharper and sharper as one played closer to the bridge. In order to eliminate this sharpness, strings are compensated/lengthened on fretted instruments.
Once "compensation" has been added however we have also lengthened the open strings, the only ones that aren't fretted and did not need to be lengthened.
Compensating the nut is done by shortening the fingerboard at the nut or by having the nut itself over lap the end of fingerboard, thereby shortening its length without modifying it.
Earvana® is one example of a pre-made compensated nut which overhangs the fingerboard, but there many others being offered today.
The Buzz Feiten Tuning system® is another popular intonation/compensation method. Modifications are made to the fingerboards length and intonation is adjusted using off-sets. How much compensation to use and how to off-set the tuning is determined using several factors such as string gauge, action, scale length etc.
More info...
Buzz Feiten®
Earvana®
Is nut compensation really necessary? I've played my buddies guitar and I don't hear the difference! These are comments I've heard before and my response is... if you don't hear any problems with your intonation then don't change it! It's that simple. If you don't think it's broke then don't fix it.
If it's so great why isn't everyone using it? Well, more and more players and manufacturer are using it. If you want to read more check out the sites I mentioned above.
For me personally, intonation became an issue once I started playing regularly and my ear improved. I think this may be the case for many budding musicians...until ones ability and ear develops they are "blessed" not to hear the inconsistencies on their equal tempered fretboard.
Tuning
Just as there are several theories about the ideal saddle and nut compensation, there are also different ways in which we can tune our instrument. I thought you just took a tuner and when the green light lit up you were in tune? :)
While this may be one of the most common methods of tuning guitars it isn't the only method.
You will find that some use harmonics to tune, some will tune 2 particular chords until they are in tune with one another and still others have devised off-set tuning charts that detail how many cents sharp or flat each individual note should be tuned.
Whatever method you find best suits your ear, simply know that there is far more than one way to tune a guitar! :)
You may find that you hear an improvement simply by choosing another tuning method.
Common Problems Adjusting Saddles for Intonation
My guitar still has sharp intonation but there is no saddle adjustment left? - Though it is rare, you may encounter an instrument that after being set up properly is still not properly intonated. When the saddle reaches it's maximum adjustment before you arrive at perfect intonation tweaks may be necessary. Kit guitars, those with radically different set ups or instruments where the manufacturer has errantly placed the bridge, small modifications may be necessary if one hopes to properly intonate it.
On bridges with springs between the saddle and bridge plate (such as the Fender® Strat or Tele style bridges) you may find that after tightening the saddle firmly against the back side of the plate more adjustment is still necessary (the instrument is still sharp). Replacing the spring with a shorter one or simply cutting the spring will enable you to increase the string length slightly. While these kinds of modifications are not normally necessary on most guitars, there are some models that require work if one hopes to play in tune.
On Gibson Tune-O-Matic/ABR® style bridges you may have already noticed that the saddle has an angled crown, flat on one side, sloped on the other. In the picture above the first saddle has been tightened firmly against the back side of the bridge in an attempt to lengthen the string and correct intonation that was too sharp. The problem is that it's not enough, the string is still too sharp. The saddle should be removed from the bridge and reversed so that the flat side of the saddle is sitting firmly against the back side of the bridge, effectively yielding more string length.
My guitars intonation is flat but doesn't change when I try to move the saddle forward and shorten the string. I hear that allot to. IF the saddle is moving either forward or backward the tuning must change. The answer is usually that sometimes when you are turning the screw, the screw itself is backing out of the back side of the bridge but the saddle itself is not moving. Make sure the head of the intonation screw is sitting firmly against the back of the bridge, you may have to push it forward to make it seat.
Another possibility, again on a Fender Strat style bridge, is that the saddle itself may be so far forward that it is hitting one of the six front mounting screws. (A maximum adjustment such as that should not be the case on a quality made instrument as the bridge itself would have to be in the incorrect position). And though this would be hard to miss, I have seen cases where people did not see the string resting on either a pickup pole piece or edge of a TOM style bridge, making that the contact point.
