Intonation - G string perfect open and at 12th fret. Massively sharp 7-9th frets - only using La Bella string

[RaNoFuNkY]

Help help.

 

I've just bought a Vintera II Precision. It's lovely. The stock strings (I assume Fender - roundwound) were fine, all played nicely with great intonation.

 

I've taken those off and replaced with La Bella low tension flats (100-42). Everything sounds great, but the G string (and only the G string) was hugely sharp at the 12th fret. No problem, I started to adjust the saddle. But, to get this thing to intonate at the 12th fret, I had to move the saddle back (i.e. away from the neck) by a crazy amount. More than I have ever seen, and it looked crazy compared to the other 3 saddles. Anyway, no problem (I thought), this was now intonated perfectly at the 12th fret and open string. However, frets 7-9 were hugely sharp. 

 

So, now the string is in tune, then becomes increasingly sharp until the 9th fret, then flattens back to pitch by the time I hit fret 12. 

 

Strange.

 

So, I put the original Fender(?) roundwound G string back on, and adjusted the saddle back to where it was, and it's perfect. No issue at all.

 

Now I have taken that original string off, replaced with the La Bella G string but kept the saddle where it works for the Fender string (thinking that I had done some wierd restringing job). But, I am back to where I started. It's in tune when played open, then massively sharp at the 12th fret. I adjust the saddle to achieve pitch both open and at fret 12, but again it's hugely sharp 7-9th frets. Like, unusably sharp.

 

The string is correctly seated in the nut and saddle, and appropriately wound. I have tried raising the action a little, then re-pitching. The neck looks fine (obviously, the bass behaves with the roundwound string). So, I am at a loss.

 

I don't quite understand the physics of this. The string gauges are perhaps a little out, but likely only 0.42 (La Bella) vs about 0.45.

 

Regardless of the physics - can anyone help me find a solution. I've got a recording session on Monday(!). Is this just a dud string perhaps?

 

Thanks!

 

 

[ezbass]

Knackered string, I’ve had this with G strings (an Ernie Ball) before. The G saddle should the furthest forward (towards the neck).