#1
Hi all,
Simple but interesting question about intonation adjustment with the adjust-o-matic/tune-o-matic bridges.
It seems that about 99.999999% of guitars have the bridges adjusted in a "zig-zag" pattern from the store. In this case the lengths of the low E and G strings are the longest, the A and B a little shorter, and the D and high E strings are the shortest.
Now, I have recently gotten a couple electric guitars (had been playing acoustic/classical with no adjustable bridge up to now) and I have adjusted the bridges so that the higher notes are in tune... and I have not ended up with the "zig-zag" pattern at all. The "zig-zag" pattern that they came with results in flatness in the G, B, and high E strings (the lower 3 strings are fine).
When I ignore what it "should" look like and just go with the tuner, I end up with the string length getting gradually shorter and shorter from low to high.
It sounds much better!
Why does everyone use this "zig-zag" pattern when it causes the high notes to be flat?
Does anyone else here do this?
#3
would you rather have a fret board that looks like this?



there's also the CFS system that fujigen uses, which is based on all strings being the same length. it's a bit different from the pic above.

and the higher frets are only slightly out of tune, until you bend anyway. then all bets are off.

there's also the use of a compensated nut, which also helps but doesn't fix everything.


like said above, it's a compromise.
I wondered why the frisbee was getting bigger, then it hit me.
#4
Something you have to understand that a ton of different things affect intonation. Scale length, action height and string gauge are 3of the biggest factors. Every string gauge has different tension, combined with varying string height is going to need different intonation.
Longer scale guitars also create more tension, meaning the note is going to be sharper when you press down.
Intonation should never be a compromise. And there is no way to "eyeball" where the saddle should be. The only true estimate is that on a tune o matic bridge, the 3 lower strings will all need the saddles further back than the high strings.
#5
Thanks for the responses.
Just for clarification, the setup that I have now is that the low E string is longest and then, each string as you go up is a little shorter, the high E being the shortest.

I am not claiming that my setup now yields perfect pitch on every fret.
I am only claiming that it is much better than before and my question is-
Why do all of the guitars use a setup in which the higher 3 strings are progressively flatter as you go up the neck?

The only thing I can think is that people actually like the higher notes to be on the low side for some reason.

Please check this out on your own guitars (check the pitch on the 5th fret and up) before criticizing my question.

PS. I am also quite interested why the zig-zag shape is not present on acoustic guitars or classical guitars at all. How is it that it's NOT necessary on a steel string acoustic, but IS necessary on an electric?
Last edited by CMCM-CMCM at Apr 9, 2016,
#6
Because it's usually what accurate intonation looks like Because of the difference in thickness and construction on the plain strings, intonating with a tuner will usually give you something in the ballpark of the zig-zag, depending on action, fretboard radius (or at least the radius' effect on action) and the height of the nut.

That's just usually (not by any means always) what it looks like when it's set correctly. In practice, other things will effect it leading to correct intonation looking slightly different, as yours does.

Here are mine, for what it's worth
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Last edited by K33nbl4d3 at Apr 9, 2016,
#7
The speaking length of the string is dependent on the gauge of the strings and whether or not they are wound or plain. Of course a properly cut nut that terminates the string at the end of the nut closest to the fretboard, and good saddle notches are assumed. The plain strings will need slightly more length as their gauge increases in size. Then the wound strings (which actually have a smaller solid core in them) often start at a length slightly less than or very close to the G strings length. Then the lengths increase accordingly as with plain strings. It's mathematically based and the only way it wouldn't work out that way is through old strings, a poor setup or just a bad intonation job.
The actual act of intonating a guitar is not a compromise and never should be, it's simply getting an open and 12 fretted note to match exactly. I use a strobe tuner as it's much more accurate than any chromatic tuner.
The scale length is the "compromise" because the position of the frets is the same for all strings regardless of strings gauge (which we've seen needs to be different for every string) so the individual notes around the fretboard are not perfect.
A good tuning method can really balance this out. I like chords played about the 12th fret to sound as good as ones played in the lower registers a compensating method with tuning using octaves is a good way from my experience. Stay away from harmonic tuning (the EDIT 7th fret harmonics are off by quite a bit).
Moving on.....
Last edited by KenG at Apr 10, 2016,
#8
Quote by kabadi.man
nope, it is impossible to set the intonation perfectly for every fret of a guitar.
i believe its neck relief that is the reason its a compromise. like i said, the amount a string stretches when you fret any particular note is different to any other fret on the same string. neck relief is not a consistent curve along the whole of the neck and therefore can not be compensated for perfectly. string height is not consitant along the whole length of the neck.
In addition, if you mostly play below the 12th fret, those frets will be worn more than those above the 12th, again another reason the lower fretted notes will increase string tension by a different amount to the higher fretted notes.



I think you are confusing terms here, when we talk intonation we are talking about the intonation setup which is open and fretted 12th only (its the only adjustment we can make after all) and that can be set perfectly. The fretting of the 12th fret note is supposed to compensate for string deflection as it represents the theoretical 1/2 point on the length of the string (ie the worst case deflection point) and when you adjust the intonation for this note you are adjusting that note with that deflection in effect.
The compromise is the scale itself, the fretboard is divided into sections that are the same for every string. That cannot be accurate because each strings length and subsequent divisions are really dependent on it's size. So many notes played in a given position on one string are not equal to the notes played in a different position on another string. This information is readily available from many good sources. A good example of this basic principal is this guitar Truetemperment which visually shows how the scale length needs adjusting for every string to be accurate -not sure I'd want to bend on this though. I've been playing for over 40 years and have changed much about my setup and tuning methods especially in the last ten years owning primarily Les Pauls and while not perfect the method I described earlier in my other post and learned from research has worked well for me and my LPs.
Moving on.....
Last edited by KenG at Apr 10, 2016,
#9
Quote by KenG
I think you are confusing terms here, when we talk intonation we are talking about the intonation setup which is open and fretted 12th (its the only adjustment we can make after all) and that can be set perfectly.

I've never limited my use of the term intonation to just the adjustment of the bridge, since the term beyond guitar generally refers to the differences between notes (so I might say that the intonation is set perfectly, meaning that it's set correctly to the 12th fret, but "perfect intonation" to me, indicates that the entire instrument is tuned perfectly to equal temperament - or another system if you've got a guitar that does that).

That said, different uses of terms aside, I don't think you're disagreeing over anything significant. But even strictly in terms of the setup, I would have to disagree with the statement that intonation should never be a compromise and point to the above image
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Last edited by K33nbl4d3 at Apr 10, 2016,
#10
Quote by K33nbl4d3
I've never limited my use of the term intonation to just the adjustment of the bridge, since the term beyond guitar generally refers to the differences between notes (so I might say that the intonation is set perfectly, meaning that it's set correctly to the 12th fret, but "perfect intonation" to me, indicates that the entire instrument is tuned perfectly to equal temperament - or another system if you've got a guitar that does that).

That said, different uses of terms aside, I don't think you're disagreeing over anything significant. But even strictly in terms of the setup, I would have to disagree with the statement that intonation should never be a compromise and point to the above image


Well we can't adjust the intonation of the fretboard, only between two notes on a single string and really only one of those two notes. But I do see where you're coming from.
Moving on.....
#11
Quote by KenG
It's mathematically based and the only way it wouldn't work out that way is through old strings, a poor setup or just a bad intonation job.


I didn't know that old strings can affect the relative pitch. Thanks. This might be part of my situation.