Vintage uke intonation

Ukecaster · Sep 14, 2018

I have a vintage soprano uke on which I've noticed some intonation issues. On the E string, I first tune it, then check the harmonic at the 12th fret, which is spot on. However, when I fret that string at the 12th fret, it is 4-5 lines sharper on my Snark. So, when I play a standard G chord down low, the G note on the E string sounds slightly sharp, and is about 2-3 lines sharper on the Snark than the open G string. I'm being careful not to use a gorilla grip, and get same result when I just lay it down and check that G note on the E string. It's not terrible, but I can hear it on the G chord for sure, and it bugs me.

The C string is similarly sharp at 12th fret, but not so much an issue on the ears while playing.

I guess I'll first try some new strings. The current strings are Martin M600, which are about 3 months old. If the result is the same, what, if anything, can be done about it?

mmn · Sep 14, 2018

First check your string height. The higher it is, the more the string stretches when you fret it, and the more intonation adjustment you need to compensate. If it's too high you may not have enough "meat" on the saddle to move the string break point enough. If it's where it needs to be then you can futz with intonation. How you do that depends on what kind of saddle you have.

Ukecaster · Sep 14, 2018

Thanks, I checked that, but the string height looks fine at about 2.25mm

mmn · Sep 14, 2018

You might want to post a picture or describe the saddle. If it's a fixed saddle, i.e. one piece bridge and saddle you could do what I did to mine, described in this thread.

https://forum.ukuleleunderground.com/showthread.php?133374-Compensation-on-a-one-piece-bridge

If it's bone or other material you likely won't be able to compensate much. Would help to see a picture, fairly close up.

EDW · Sep 14, 2018

Fluorocarbon are significantly thinner than nylon due to their density. Perhaps that has some effect. I have sometimes wondered if it would help to use a string which is more like what would have been originally on the instrument.

Mind you, this is pure speculation on my part with no scientific basis!

stevepetergal · Sep 15, 2018

Ukecaster said:
On the E string, I first tune it, then check the harmonic at the 12th fret, which is spot on. However, when I fret that string at the 12th fret, it is 4-5 lines sharper on my Snark.

Uhh...just so you know, the harmonic is not the string cut in half by a fret. When you play an harmonic, the note is determined by the string's vibrations. It will always divide itself where the vibrations from the opposite ends of the string meet. When you pluck an harmonic near enough the 12th fret, the vibrations will divide the string at the exact center, so the harmonic cannot be anything but "spot on." You'll never get a flat or sharp harmonic.

Ukecaster · Sep 15, 2018

stevepetergal said:
Uhh...just so you know, the harmonic is not the string cut in half by a fret. When you play an harmonic, the note is determined by the string's vibrations. It will always divide itself where the vibrations from the opposite ends of the string intersect. When you pluck an harmonic near enough the 12th fret, the vibrations will divide the string at the exact center, so the harmonic cannot be anything but "spot on." You'll never get a flat or sharp harmonic.

Got it, I never expect a flat or sharp harmonic, but compare it to the 12th fretted note, which should match AFAIK.

stevepetergal · Sep 15, 2018

That's right.

Bill Sheehan · Sep 15, 2018

John, is your bridge a "compensated" bridge? If not, and if just one or two of your strings are acting up, you may indeed find that a fresh set of strings will correct the issue. If the problem persists, then I wonder if the nut slots on the offending strings might need to be deepened a tad?

EDW · Sep 15, 2018

Bill Sheehan said:
..... if just one or two of your strings are acting up, you may indeed find that a fresh set of strings will correct the issue.

Recently I had this happen. My C string was strangely out. I replaced that string and it was much better.

Ukecaster · Sep 15, 2018

Thanks all, will just try some new strings before I fret too much about it

Bill Sheehan · Sep 15, 2018

EDW said:
Recently I had this happen. My C string was strangely out. I replaced that string and it was much better.

I've experienced that same thing several times, EDW, where just one string (usually a brand new one, right after installing a new set) is annoyingly sharp (or, in some instances, flat!) at the 12th fret, whereas all of the other strings are perfectly accurate. This is always a head-scratcher when the saddle is just the regular straight-across bar style (rather than being of the compensated variety); it would seem that, with the regular bar-style saddle, ALL of the strings would be either "in" or "out", as a group.

Jarmo_S · Sep 15, 2018

Remember that there is always the bonfire possibility. For an uke that is not intonated properly on bridge ... it can be corrected. Think about costs and sentimental values you may have for it.

Vintage uke intonation

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