Intonation Sharp on C String

[Joralin]

Hello Guys,

i have a Ukulele that has a sharp intionation on the C String ( About 20+).

The Intonation gets better if you move up the fretboard, at fret 12 its about 5+, what i would be fine with.

But the first frets are really bad. The problem shouldnt be the string height at the nut, (fret 1). Its about 0,5mm.

The Strings are lso not part of the problem, i tried 3 different brands.

But i have the feeling the saddle/saddle slot is causing that problem in some other way.

Is there a way to test if the saddle is the problem? Im also open for other ideas ...

 

[John Colter]

If the other three strings are satisfactory, I don't see how the saddle, or the slot within which it rests, can be the culprit. You have eliminated the probability of the string itself being faulty and you are happy with the string height. I'll have to think about this one.

 

[Graham Greenbag]

Hello Guys,

i have a Ukulele that has a sharp intionation on the C String ( About 20+).

The Intonation gets better if you move up the fretboard, at fret 12 its about 5+, what i would be fine with.

But the first frets are really bad. The problem shouldnt be the string height at the nut, (fret 1). Its about 0,5mm.

The Strings are lso not part of the problem, i tried 3 different brands.

But i have the feeling the saddle/saddle slot is causing that problem in some other way.

Is there a way to test if the saddle is the problem? Im also open for other ideas ...

I had a similar problem on an inexpensive Uke. The Uke was well set-up but still sharp. Eventually I tracked the fault down to a poorly moulded nut; whilst the string hight was good the nut slot didn’t support the string next to it’s exit from the nut. I blanked the end of the nut off with masking tape, topped the slot up with super glue, recut the slot and all was well.

 

[Joralin]

the nut slot didn’t support the string next to it’s exit from the nut

Thanks for the tip. Well im not sure i understand that sentence (i reapired some ukes, but never did anything at the nut).

Did you meant the exit from the nut to the fretboard, or from the nut to the headstock?

How should it support it?

 

[Graham Greenbag]

Thanks for the tip. Well im not sure i understand that sentence (i reapired some ukes, but never did anything at the nut).

Did you meant the exit from the nut to the fretboard, or from the nut to the headstock?

How should it support it?

As the string exits the nut, next to the fretboard, that last part of the string should still firmly rest on (be supported by) the slot’s base within the nut. If that’s not the case then it’s free or vibrating length starts within the nut rather than at the edge of the nut.

The Uke that I repaired had a poorly moulded nut with slots that did not support the strings as the exited the nut next to the fretboard and hence their free lengths were wrong. That made the relative position of the first few frets wrong too and so notes were sharp at that end of the fret board.

 

[Joralin]

As the string exits the nut, next to the fretboard, that last part of the string should still firmly rest on (be supported by) the slot’s base within the nut. If that’s not the case then it’s free or vibrating length starts within the nut rather than at the edge of the nut.

The Uke that I repaired had a poorly moulded nut with slots that did not support the strings as the exited the nut next to the fretboard and hence their free lengths were wrong. That made the relative position of the first few frets wrong too and so notes were sharp at that end of the fret board.

If i understand you right, the intonation of a ukulele is calculated from the bottom part of the nut, down to the saddle?



I made a sketch, so maybe its eaiser to explain how i understood it.

Please tell me if im correct.


Red = highest point (in height) of the nut, where the string should rest
Green = lowest point (in height) of the nut

 

[Graham Greenbag]

If i understand you right, the intonation of a ukulele is calculated from the bottom part of the nut, down to the saddle?



I made a sketch, so maybe its eaiser to explain how i understood it.

Please tell me if im correct.


Red = highest point (in height) of the nut, where the string should rest
Green = lowest point (in height) of the nut

If you stood the Uke vertical with the headstock at the bottom and the bridge at the top then your picture would be correct in its assignment of top (red) and bottom (green) edges of the nut. The scale length is the distance from the nut’s top edge (coloured red in your sketch) to the crest of the 12th fret times by two, the distance from the nut to the saddle will be the scale length plus say a couple of mm of compensation.

The frets are positioned relative to the nut’s red line face and for intonation to be correct the string must be supported within the nut right up to the (red) face of the nut.

 

[bbkobabe]

Funny... I sharp my A intentionally... it just sounds right to me somehow...

Probably my audiences would not agree!

 

[anthonyg]

Are all the other strings good?
Are you using an un wound C string?
This is exactly why string sets with a wound 3rd (C string) are available.
Do you want good intonation, or do you want an unwound 3rd string?

Compromises, compromises.

 

[Brian PacNW]

Just wanted to share that I also had a C string that was about 15 to 20 cents sharp at the 12th fret if I pressed moderately firm like normal playing. It was sharp on most frets except the open position, really. This was on a brand new intermediate-priced uke (Millar), not some cheap thing, so I was bummed of course.

Switched out the stock strings hoping for an easy fix (looked like nylon I think? very clear and thick) with some new fluorocarbons and it seemed to fix the issue. Whew!

 

[Graham Greenbag]

Just wanted to share that I also had a C string that was about 15 to 20 cents sharp at the 12th fret if I pressed moderately firm like normal playing. It was sharp on most frets except the open position, really. This was on a brand new intermediate-priced uke (Millar), not some cheap thing, so I was bummed of course.

Switched out the stock strings hoping for an easy fix (looked like nylon I think? very clear and thick) with some new fluorocarbons and it seemed to fix the issue. Whew!

That’s often the way of things, fluorocarbon strings need less compensation than nylon strings …

The original post post might confuse folk, it’s rare for strings to be sharp at the nut end of the fret board (as in this case) and not uncommon for them to be sharp at the saddle end of the fretboard.

 

[Brian PacNW]

That’s often the way of things, fluorocarbon strings need less compensation than nylon strings …

The original post post might confuse folk, it’s rare for strings to be sharp at the nut end of the fret board (as in this case) and not uncommon for them to be sharp at the saddle end of the fretboard.

Oh you’re right, completely missed that the intonation problem was on lower frets.

 

[greenfrog]

Funny... I sharp my A intentionally... it just sounds right to me somehow...

Probably my audiences would not agree!

In what key(s) does it feel right to sharp your A?

Modern “equal tempered” western instruments use 12 notes that are a compromise so they can be used in any key, but aren’t exactly right in most keys. You may be hearing that the interval between your A and another note doesn’t sound quite right, and sharpening your A in response.

I’ve started a separate thread on the subject here to avoid dragging this thread off topic.