Fixing intonation on an Ohana bari

[John boy]

I decided to post this question after reading a post in the main "Talk" forum about intonation.

The intonation on my Ohana bari goes flat at the fifth fret and stays that way all the way up the neck. So if I have the open strings all tuned, they stay in tune until I move up to the fifth fret. At that point, the go flat (actually the first string starts going flat at the fourth fret).

Please let me know if I'm correct in the following assumption or if I'm off base. If I'm playing a string at the fifth fret and it's flat, then the length of string that's in play (the portion between the fifth fret and the saddle) is too long -- because longer strings have lower pitch. Correct, or not?

And if that's the case, then to shorten the string, I could lower the saddle or bridge?

In case it's helpful, I measured and found that the nut-to-saddle distance is 2x the nut-to-12th-fret distance PLUS 1.5 inches.

I realize it may be hard to respond if you haven't seen and played my instrument. Any insight or suggestions would be appreciated. Thanks in advance.

[Rakelele]

Lowering the saddle may be a way to go as long as you don't have to go too low to make the strings buzz. Additionally or alternatively, you'd have to bring the saddle closer towards the nut. Or try a different string set. If I remember correctly, fatter strings would sharpen the pitch to some extent.

[anthonyg]

I decided to post this question after reading a post in the main "Talk" forum about intonation.

The intonation on my Ohana bari goes flat at the fifth fret and stays that way all the way up the neck. So if I have the open strings all tuned, they stay in tune until I move up to the fifth fret. At that point, the go flat (actually the first string starts going flat at the fourth fret).

Please let me know if I'm correct in the following assumption or if I'm off base. If I'm playing a string at the fifth fret and it's flat, then the length of string that's in play (the portion between the fifth fret and the saddle) is too long -- because longer strings have lower pitch. Correct, or not?

And if that's the case, then to shorten the string, I could lower the saddle or bridge?

In case it's helpful, I measured and found that the nut-to-saddle distance is 2x the nut-to-12th-fret distance PLUS 1.5 inches.

I realize it may be hard to respond if you haven't seen and played my instrument. Any insight or suggestions would be appreciated. Thanks in advance.

Your kind of on the right track.

Now 1.5 INCHES of saddle compensation is just insane! DO you mean 1.5mm?
Also adjusting the height of the strings only makes a minor difference and lowering the bridge would only act to flatten the intonation a little more.

The intonation being good for the first 4/5 frets and then going flat further up the fretboard leads me to suggest that the nut is fine and its the saddle contact point that are too long and need to be shortened a little.
Do you really mean 1.5 inches of compensation (which is a crazy amount) or 1.5mm?

[Col50]

You can use the calculator to see how your fretboard compares

https://www.stewmac.com/FretCalculator

[John boy]

Your kind of on the right track.

Now 1.5 INCHES of saddle compensation is just insane! DO you mean 1.5mm?
Also adjusting the height of the strings only makes a minor difference and lowering the bridge would only act to flatten the intonation a little more.

The intonation being good for the first 4/5 frets and then going flat further up the fretboard leads me to suggest that the nut is fine and its the saddle contact point that are too long and need to be shortened a little.
Do you really mean 1.5 inches of compensation (which is a crazy amount) or 1.5mm?

I really mean the crazy amount. Inches. When you say the saddle points are too long, you mean too high, correct?

And thanks to all for your responses. The bridge appears to be glued on so I don’t think I can move it.

[John boy]

Col50, thanks for posting the Stewmac calculator. According to that, my nut to saddle length is right on. But my nut to 12th distance is nearly 3/4-inch too short. Interesting.

[Rakelele]

The (wooden) bridge is glued on and replacing it would be a lot of nerve-wrecking trouble, but the actual saddle (the white bone part that sits in the bridge) isn't. It could be reshaped to move to contact point closer towards the nut, as I suggested above. However, before adjusting any of the hardware, I'd just try different gauges and materials of strings that might be a better fit for the specific build of your instrument. Are your issues occurring with the factory strings, or did you or a previous owner change the type of strings?

[John boy]

Thanks for the advice, Rakelele. I'm not sure I have the expertise to reshape the nut, though I could try. I've changed strings a couple of times (I bought the uke new. I don't know what the stock strings were). I tried Worth Browns and just recently put on D'addario Titaniums, wondering if that would help alleviate the intonation issues, but it didn't.

However, one other thing occurs to me that could be contributing to it. I have that uke tuned lower than usual, to A-D-F#-B. The low A string is a classical guitar A string. The D, F# and B strings are the D'addario baritone D, G and B strings, but I've got each of them moved up one position (the D string, which is usually the fourth string on a bari, is in the third string position, etc.). I didn't widen the nut slots when I moved those three strings up one position, so it may be they're sitting too high up in the nut. I will check into this and report back after I've done so.

I appreciate everyone's responses thus far, so thanks all.

[anthonyg]

I really mean the crazy amount. Inches. When you say the saddle points are too long, you mean too high, correct?

And thanks to all for your responses. The bridge appears to be glued on so I don’t think I can move it.

A 1.5 INCH error is huge and I'm having trouble believing that the intonation could possibly be good over the first few frets with an error like that.
Something isn't adding up.

The first thing that comes to mind is that these measurements need to be taken from string contact point to string contact point. You don't measure to any point on the bridge (the larger part that's glued on). You measure to the saddle (usually a thin white piece that is located within the bridge).

When I say length I'm talking about measurements along the axis/length of the strings. For the intonation to be right for the first few frets and THEN go flat you only have a small error, nothing like 1.5 inches and I'm saying that its in the length along the string axis. The contact point on the saddle (not the bridge) is a little long.

What are the actual numbers we are dealing with?

[John boy]

Indeed, it is a huge error -- it's so huge that it's not accurate! Your instincts were right on, Anthony. There's an old saying about "measure twice, cut once." In my case it should be "measure four times." Apologies for my ridiculous measuring error. I went back and rechecked, and here are the actual numbers:

Nut to 12th -- 9 and 10/16 inches. Nut to saddle -- 19 and 10/16 inches. So if you take 2x the nut-to-12th, that gives you 19 and 4/16 inches. Ergo, the difference between that and nut-to-saddle is only 6/16 inches, or less than half an inch.

I'll also add this -- after my post, I removed the low A string and re-strung the uke with the normal DGBE strings in their proper slots on the nut. This seems to have eliminated the intonation problems for the first and second strings (the two highest strings). The lower two strings (D and G, which are both wound) still have intonation problems.

I appreciate everyone's responses, and apologies again for creating something of a false alarm with my mismeasurement this morning. I gotta get these eyeglasses checked....