Taking another shot a strange intonation issue

[EZYPIKINS]

For my benefit, can you tell me what kind of tuner is measuring "spot on" intonation on every fret?

[SkipII]

Originally Posted by EZYPIKINS

For my benefit, can you tell me what kind of tuner is measuring "spot on" intonation on every fret?

It is a phone app, Burt what I mean by "spot on" is within 3 cents or so up and down the neck, except for this A string issue.

[SkipII]

Originally Posted by John Arnold

I cannot see how this set of circumstances can be caused by anything but a bad string, no matter how many sets have been tried.
1) The frets are in the right place, evidenced by the fact that intonation is good on the other strings.
2) The nut and saddle are properly placed, because intonation at the 12th and the first position is good.
Assuming that the frets are properly leveled and crowned, that leaves the string as the culprit. For good intonation, the string must be perfectly uniform along its length. Even a variance of 0.0005" in the diameter will mess it up.

After three sets of strings, I'm not prepared to narrow this down to a string issue. I think the resonance theory might be the right direction.

[SkipII]

Originally Posted by Glen DeRusha

I am not going to believe that the frets are in the right place, until I have said guitar in hand and measure them for myself. Been there, done that. And not to long ago.

Sometimes it is good to review the basics.

I'm not going to rule out the angle of the nut slot just yet. If everything is spot on at the nut, it must have a compensated nut? Is it original equipment? Or after market nut compensation?

I am not going to believe that everything is spot on at the 12th either. Not the way I measure things.

And what does that saddle look like?

I have checked the intonation with two different tuners, including a Strobostomp. The intonation at the 12th fret is dead on when fretted and harmonic.

The guitar comes with a compensated saddle, but likely standard shaping by CNC.

[SkipII]

I'm starting to think this might a a top resonance issue. I've been measuring the pitch right when I strike the strings (attack). It goes flat on attack (when first struck), but when the note decays (sustains, fades), it drifts back up to dead on pitch.

[Glen DeRusha]

Ball end of the 4th string might not be seated up against the bridge plate. Slotted bridge pins? Solid bridge pins?

The saddle might not be fitted 100% to the bottom of the saddle slot?

Sometimes a leaning saddle can benefit from sanding the bottom of it a little bit out of square? For example to make an under saddle pickup work better.

[SkipII]

Originally Posted by Glen DeRusha

Ball end of the 4th string might not be seated up against the bridge plate. Slotted bridge pins? Solid bridge pins?

The saddle might not be fitted 100% to the bottom of the saddle slot?

Sometimes a leaning saddle can benefit from sanding the bottom of it a little bit out of square? For example to make an under saddle pickup work better.

Three sets of strings, all seated properly against the bridge plate. Slotted pins.

How would any of that affect intonation on a particular part of the neck?

[Glen DeRusha]

Because one day I had the ball end of the 4th string hanging down about 1/2" and it caused a bunch of wolf notes that you would not believe.

If it was me, I would change to solid pins and slot the bridge and plate. Depending on what the bridge and saddle look like now.

If I was you, I would ask John Arnold what he would do with the pins. For structural and sonic reasons.