Intonation

[Larry Parker]

I am a little confused about adjusting intonation: Some teachers say the 12th fret should right on with the open string (Erelewine), other say due to string vibration, etc. it should be set a little flat (Kent Everett). Any insight on this would be appreciated.

Larry

[Tim Mace]

Only if you got the gut ,Bob! My great great great grandcadaver was a lute maker.

[Bob Webster]

Very good! Sadly, no one would disppute that I have the gut for it. Hard earned.

Cheers,
Bob

[Bob Webster]

As I suspected, a Mr. Feiten, of BuzzFeiten, has a patent on what has to be the most thoroughly manipulated method to get great sounding intonation on guittars. His patent is at the link http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITO..."guitar+intonation"&RS="guitar+intonation". Fascinating reading, lots of heresy, and probably a method that works.

Bob

[danove]

Agree on that inharmonicity Bob.
A sustained note sort of sharps up in the tail, noticeably in the lower strings.

My own folk music area is quite simple, compared to that of a classic player,
and is limited to closely related keys, so I tend to tune the finishing notes
a bit low for a scope to act within while playing.

There is the "True Temperament" steel string fretboards
in Stockholm, doing intonation for each string.
I am not related to them in any way (except beeing sweedish),
but I have tried an acoustic with one of their formulas.
Looks funny, but a pleasure to use.

Thanks for the link.

Dan

[Bob Webster]

Hi, Dan. I contacted Greg Byers via email and asked him to look over the discussion in this post and give his input. He has and I quote his reply below with his permission:

"Hello Bob:
>
> It looks like you are beginning to see the complexities involved in
> the intonation problem. Moving frets from the nominal equal-tempered
> position is basically a non-starter. In my solution I don't expect
> every note to be exactly in tune. Rather, I treat it as an
> optimization problem and look for the best fit of the data to an equal
> tempered scale. The best you can do, in my opinion, is optimize the
> positions of nut and saddle for the given conditions (strings, nut and
> saddle height, etc.), and do the best you can to get the frets placed
> with precision. I go for +/- 0.1 mm, with an occasional outlier at +/-
> 0.2 mm. I hope this helps!
>
> Best Wishes, Greg
>
> Gregory Byers, Luthier
> 15000 Hearst Road
> Willits, CA 95490"

[danove]

Great info, Bob!

That saved me from another trial and error.

My regards to you both.

Dan

[John Cadd]

I don`t think a player can do much to really alter anything once the frets are in position.My small adjustments to get a good "scale" on each string were a lot easier because the frets were brass and a lot easier to deal with.A flat octave would drive me insane .The most I would risk would be a wee bit of careful filing at the bridge.One point I was curious about.How much effect does the overall stiffness of an instrument have on details of tuning?Effect of carbon reinforcement for instance.

[Tim Mace]

xtremely close has served me well and no matter how close you get ,instruments change...weather,age,strings,tension and on and on.

[John Cadd]

I am new to guitars but well used to violins .(making and playing).I bought a Spanish bottom range model and started to assume there was an accepted compromise that guitarists always lived with.A bit out of tune.When I bought a Mexican requinto it was much more in tune and I decided to explore why.Starting with the requinto.The nut was already right and made of bone.The octaves were not "exactly" right and as a violin player I was in no doubt at all.The difference was minute but there.So if you want to be sure when checking this bit get a violin player to help you .-----Assuming the frets are already level.--slacken all strings and gently tie away from the fretboard---Put masking tape between frets-----Coat the frets with a felt marker pen.That ensures no metal will be taken from the centre of the frets when you do small adjustments.Get the octave fret No 12 in shape first.Well,------round off the edges anyway.I dont like frets to be too thin as you have less chance for adjustments.---Now put all the strings back and tune up.------Then carefully play the open string and octave as you would normally (forget the harmonics for now ) to check exact tuning.(enter violin player).--Hear if the octave is sharp or flat and write a list as a reminder.A sharp octave needs a small adjustment to the front of the bridge bone.This will slightly increase the length of vibrating string.A flat octave will need an adjustment to the back of the bridge This will slightly reduce the vibrating length. This will only work if you start with a bridge bone that has a circular cross- section- top-edge shape to start with.If this messes up the action you can fit another later with added refinements built in.So having all the octaves correct you can check the major scale on each string.Remember the guitar is strung up and single strings are relaxed for bridge adjustments .I used a soft piece of dry fine oilstone to make small adjustments to individual frets .Protect strings as much as possible and clean off as you go.Make a groove in the fine oilstone to match the fret radius and cut a central slot in the groove to AVOID contact with the centre of the fret. Just work on one side of the fret to adjust the tuning.(top edge or bottom edge)Get the scale as accurate as you can,especially the seventh note of the scale.ie FRET 11.----I am just a beginner with guitars ,but this worked beautifully and I have no problems with intonation at all now.So use the official scale measurements .Dont have frets too thin .Have a rounded bridge top.Do all the fine tuning with your ears and not a meter.When it`s all in tune take strings away (tie back) and polish the frets witth a grooved piece of wood and some metal polish.Dont get the fretboard messed up.Remove masking tape from fretboard.--Really I`ve been lazy as I didn`t think to alter or check the semitones that are missed by the Major scale.But it`s fine as it is now.I`m a happy bunny!--You see a violin has to be checked for intonation on every note played and the fingers get used to compensating automatically ,but it`s a continuous process.ONLY TINY AMOUNTS OF METAL WERE REMOVED.Too little for the eye to see.But the effect on tuning was dramatic. I tested a lot of guitars last weekend in a shop near Liverpool and only one was in tune all the way up every string----made in CHINA.Cheapest model in the shop and you would normally use it on a beach for a Tennis Racquet. (How you say?---GO FIGURE!)

[danove]

This picture gives a hint to what is required if the frets are to be adjusted
to a formula near equal temperament tuning - provided no compensation in the nut.

A compensated nut, sort of straightens out thees winding frets,
so there might be some improvement from your method, John,
except maybe not to that annoying g-string....

[John Cadd]

Danove .I have tried to understand a bit about tuning but have not got my head around compensated nuts yet.More homework required I think.That is a "diagram "I hope.My bit of success may be "just a bit of dashed luck"as Bertie would say.

[Brent Hutto]

When I first started looking for a classical guitar I began at the bottom end of the (practical) range by examining all the $200-class guitars I could find locally. I found one Takamine Jasmine made of laminated birch and solid spruce with a "mystery wood" fretboard that was the intonation champ. According to my Peterson strobe tuner there were only a couple of spots more than a cent or so out of tune and they were mostly around the 1st fret (the nut slots were too high). I've never before or since seen a nylon-string guitar that close to perfectly intonated, in fact it seemed closer than I understand to be theoretically possible on a guitar. Maybe my measurements were off somehow but chords and intervals sounded very sweet.

Unfortunately, the tone of the guitar was approximately that of six strings stretched between hooks and suspended in the air. Just no resonance or sense of the guitar's body contributing whatsoever. But it played easily and played in tune, I hope some beginner kid ended up with it to learn on because it would be much less frustrating than the sour-tuned cheapies most end up with it.