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U-Bass String Intonation Issue ... something for the Troubleshooters

Hi all,
I'm not sure if Strings or Setup is the right forum, so feel free to move the thread.

I've ordered a set of flatwounds for my U-Bass and the Universe does not want me to have that.
The first set I ordered was taken home from work by my SO - and disappeared.
I've ordered it along with two sets of strings for her acoustic guitars, so it was in her best interest to get the parcel home safely - but it is nowhere to be found.
A few weeks passed and I decided that they won't resurface so I ordered another set.
That set made it home, and I got to work.
The U-Bass in question is a red Kala Journeyman. It came with roundwound strings (and not the rubber kind). The strings in question are made by Galli for Kala - for the Kala U-Bass.

The A, D and G strings fit perfectly and work as intended.
The E string is giving me some trouble, though.
It seems that the String is a bit bigger than the rest (I mean in relation). It would not fit the nut and inserting it through the hole in the body was only possible by pulling rather hard. The silk on the heel of the string is a bit longer than on the other strings, so it was sitting on the saddle of the bridge.
IMG_20210620_220321.jpg
With the string like this, sitting too high both on the nut and on the bridge, the intonation was off. I would have expected a string that's way too high to intonate sharp on fretted notes, this one, however was about 50 cent flat.

I tackled both problems:
In case of the bridge, I pulled the string out and inserted a nut between ballend and bass, so it sits deeper and the silk is not touching the saddle any more.
In case of the nut, I used a file to make the hole wide and deep enough so it sits comfortably. I checked the intonation throughout this process, but it stayed the same.
Tuned to E, all fretted notes are 50 cent flat.
When I fret a note and tune the string to that tone, no matter where (I tried 1st fret F and 5th fret A), all the fretted notes are spot on, but the open E is 50 cent sharp.
I'm quite out of ideas.
The only thing I could try is to drill the hole through the body a bit larger. The other strings fit well, while the E string sits very tight. I don't know how this might have any effect on the intonation, but that's the only thing left that's different from the other strings.

Any Ideas / Experiences?
 
Honestly I had this same problem with the E string on my Journeyman with the stock silver-wound strings. To fix this, I set the witness points at the bridge and nut, then re-tuned using an external tuner and checked it using harmonics. It's still not perfect, but it's close to where it's not that noticeable.
 
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If all of the frets are in relative tune when you tune to a fret, the nut needs "moved." Right? In your case, the nut edge needs to move towards the headstock. That would make the string longer so slightly more tension which would raise the pitch of fretted notes. A compensated nut.

But adjusting the nut for one type of string would then make it wrong for others. Hmm.
 
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If all of the frets are in relative tune when you tune to a fret, the nut needs "moved." Right? In your case, the nut edge needs to move towards the headstock. That would make the string longer so slightly more tension which would raise the pitch of fretted notes. A compensated nut.

But adjusting the nut for one type of string would then make it wrong for others. Hmm.

Adjusting the nut would be fine, since I intend to stick to flatwound strings on the U-Bass. AFAIK there's only the one brand to choose from - so there's that.
The thing I don't really get is that the nut seems straight - when I measure it from the nut to the 1st fret on the G string and on the E string, I get the same value, and the G string works fine.
 
Honestly I had this same problem with the E string on my Journeyman with the stock silver-wound strings. To fix this, I set the witness points at the bridge and nut, then re-tuned using an external tuner and checked it using harmonics. It's still not perfect, but it's close to where it's not that noticeable.

I double checked that and even went as far as reinstalling the string, taking care of the witness points. No change whatsoever.
 
Hi all,
I'm not sure if Strings or Setup is the right forum, so feel free to move the thread.

I've ordered a set of flatwounds for my U-Bass and the Universe does not want me to have that.
The first set I ordered was taken home from work by my SO - and disappeared.
I've ordered it along with two sets of strings for her acoustic guitars, so it was in her best interest to get the parcel home safely - but it is nowhere to be found.
A few weeks passed and I decided that they won't resurface so I ordered another set.
That set made it home, and I got to work.
The U-Bass in question is a red Kala Journeyman. It came with roundwound strings (and not the rubber kind). The strings in question are made by Galli for Kala - for the Kala U-Bass.

The A, D and G strings fit perfectly and work as intended.
The E string is giving me some trouble, though.
It seems that the String is a bit bigger than the rest (I mean in relation). It would not fit the nut and inserting it through the hole in the body was only possible by pulling rather hard. The silk on the heel of the string is a bit longer than on the other strings, so it was sitting on the saddle of the bridge.
View attachment 4312457
With the string like this, sitting too high both on the nut and on the bridge, the intonation was off. I would have expected a string that's way too high to intonate sharp on fretted notes, this one, however was about 50 cent flat.

I tackled both problems:
In case of the bridge, I pulled the string out and inserted a nut between ballend and bass, so it sits deeper and the silk is not touching the saddle any more.
In case of the nut, I used a file to make the hole wide and deep enough so it sits comfortably. I checked the intonation throughout this process, but it stayed the same.
Tuned to E, all fretted notes are 50 cent flat.
When I fret a note and tune the string to that tone, no matter where (I tried 1st fret F and 5th fret A), all the fretted notes are spot on, but the open E is 50 cent sharp.
I'm quite out of ideas.
The only thing I could try is to drill the hole through the body a bit larger. The other strings fit well, while the E string sits very tight. I don't know how this might have any effect on the intonation, but that's the only thing left that's different from the other strings.

Any Ideas / Experiences?

I don’t know which flat wound you are using, but this info is listed with Ubass by Galli flatwounds KA-BASS-4FW;

Modifications to the nut slots and string holes by an experienced instrument technician may be required. As a streamlined alternative to modifications to the existing nut, the Flat Wound U•BASS® Nut by TUSQ® is available for purchase, to be installed by an experienced instrument technician only. Due to the change to a higher tension as well, a truss rod adjustment is also recommended.
 
With the string like this, sitting too high both on the nut and on the bridge, the intonation was off. I would have expected a string that's way too high to intonate sharp on fretted notes, this one, however was about 50 cent flat. Any Ideas / Experiences?
I had the same experience on my bubinga Kala U-Bass. Everything intonated flat. My luthier and I discussed moving the bridge. Not feasible. Then I had an idea. I took a post-it note and on the edge marked the length between the middle of the 12th fret and the 13th fret. I then folded over the post-it note and made the next mark to double the length, since the distance between the fretboard edge of the nut and the 1st fret should be exactly double the distance between the crowns of the 12th to the 13th frets. When I unfolded the post-it note and measured the outside marks, my nut to 1st fret distance was too short. I took the post-it note and my U-bass back to my luthier, and he put a spacer at the end of the fret board to lengthen the distance to what it should be. Now my U-bass plays in tune as perfectly as a fixed bridge instrument can.
U-bass Nut.jpg
 
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