Intonation Question

[firstbassman]

Here is dumb question number . . . ?

I was fooling around on guitar last night, re-tuned and decided to check the intonation on a fairly recently purchased Epi Dot Studio.

All open strings were in tune, then fretted at the 12th fret on high E and it was way sharp (as were other strings too). Adjusted the saddle and it was still sharp. Decided to play harmonic on 12th fret and it was PERFECTLY dead on in tune.

So my question –

Should the guitar be “in tune” when various notes are fretted up and down the neck, or is intonation correct if the harmonics (7th fret, 12th fret, etc.) are in tune?

Thanks!

[jdogric12]

Play the harmonic on 12 first. Then play the fretted note on 12. Adjust the saddle to correct the fretted note; the two should both/each match the open string.

On a related note, NEVER tune to a 7th fret harmonic. It is a perfect fifth above the fundamental, and perfect fifths are naturally sharp. It's just a math thing. I cringe whenever I see people do that thing where they tune the strings with 7 fret harmonics. They finish the sequence and wonder why they are still out of tune.

I tune various notes on various frets. For example, I tune High E 3fr to G open, B 3fr to D open, A open to G 2fr, Low E 3 fr to G open, A 2fr to B open, etc. Kind of a criss cross mix and match pattern.

[firstbassman]

Thanks Jason!

But there lies the dilemma. The open and 12th fret harmonic are spot on. But the 12th fret pressed down is way sharp.

Now, I’ve been known to have a (too strong) of a grip and I could be bending the string sharp as I press down. But then again, the low E and A had similar results too.

I may have to break down and bring it in to my local tech.

[blueflamerick]

No dilemma. Keep moving the saddle until the note at the 12th fret is in tune with the harmonic.

[jdogric12]

Yep, move the saddle away from the neck if your fret is sharp.

[jdogric12]

Uh, I think, anyway. It's hard to picture without a guitar in my hands.

[blueflamerick]

I thought it was shorten the string (move saddle towards neck) if sharp, lengthen string if flat.

[firstbassman]

No, Jason is correct.
If flat, shorten the string.
If sharp, make string longer.

On the Epi Studio, this turning out to be a bit of a pain because the screws face toward the neck, under the strings.
Who thinks up these stupid designs?

[beatlefreak]

It's easy when you think about it. Intonation is getting the twelfth fretted note exactly one octave above the open note. If the fretted note is sharp, move the saddle away from the headstock - Lengthening the string. therefore making it lower in pitch. You also lengthen the string on the open note, so you have to retune, then check again. Intonation works because although the open string is also lengthened, the note will be lowered only half as much as the fretted note will.

[wayang]

It's easy even when you don't think about it: shortening the vibrating portion of a string, whether by fretting it anywhere, moving the saddle in the neck direction or running a beer bottle neck along it will produce a higher pitch...shorter equals higher.

...and I plan to be higher shortly...

[lyle_from_minneapolis]

Just to clarify one point that may or may not have been fully understood: the octave harmonic will ALWAYS be in tune to the open string. It is dead center of the string length (between nut and saddle) and will always chime correctly.

What gets adjusted are the variations of distance that come into play when you press the string down to a fret, causing slight change of pitch. But once those are corrected, the middle harmonics will still be perfect, independent of these adjustments.

[jdogric12]

True, Mark. Thanks for the note. Well added.