Intonation at the nut

[Henning]

Hello, to make the g string of my classic guitar play in tune, higher up the fretboard, a 8.4 mm compensation at the nut has to be applied. This is found by experiment and the tone of the open g string doesn't sound so good (slight buzzing). But 8.4 mm(!), that is awful much, isn't it?
8.4 mm = 1/3" , so the g# will be about 17% out of tune.

[Fathand]

If the tone of the G string is off and buzzes, try a different string and check for buzzing caused by a high fret.

Why would only the G string be that far off?

[Bowie]

I always intonate at the nut and it can get complicated depending how close or far from the 1st fret the nut is. In theory, it should be in line with fret spacing but it doesn't always work out that way, intentionally or not.

If you are saying that you lowered the slot and it started buzzing when it reached ideal height, then the only answer may be to make a nut that sits slightly over the fret board on the G, so that you can get a balance between intonation and action.

[Alan Carruth]

Compensating the nut has the most effect at the lowest frets. If the intonation is out higher up you probably need to compensate the saddle more.

[Henning]

Originally Posted by Alan Carruth

If the intonation is out higher up you probably need to compensate the saddle more.

Yes, that's the way I will try. Thank you, thank you all for your contributions.

[nikpearson]

The 3rd string does usually require more saddle compensation than its neighbours, but that seems a lot more than normal. A classical saddle is usually positioned so that the centre is 1.5 mm or so beyond the scale length. This provides general compensation but I then add two wave profiles - one for the wound basses, one for the monofilament trebles - to the saddle top to make individual string adjustments. I can usually adequately compensate within the width of a typical saddle 2.5 - 3 mm.

I recently built a 10-string Yepes tuned guitar which presented additional compensation issues due to more strings and extra thick low C. A typical nylon G could not be fully compensated within the saddle width. Changing it to a denser and narrower fluorocarbon allowed adequate compensation with the saddle width available.

My suggestion would be to check intonation again carefully, preferably with a new 3rd string to take a bad string out of the equation. Where do the other strings contact the saddle? The G often needs to be close to the back edge of the saddle. Fret the string just hard enough to avoid buzzing. It’s very easy to over deflect the string and think the intonation is out.

Lastly, try a fluorocarbon string. The smaller the diameter the less compensation is needed.

Hope that helps.

[Howard Klepper]

What part of the fretboard plays in tune with 8.4mm nut compensation? That is way too much, and suggests that the bridge and saddle are not located right, or the frets are not accurately placed, or both.

[Henning]

I had put on a g string of different brand. That caused the issue. I now have a very old set (since 1.5 year perhaps) but have changed the g string back to what it was. The intonation is better. However, the tone turned out to be softer higher up the fretboard with the new brand g string.

[redir]

8.4mm is way out of whack. I would check to see that the bridge was placed in the right spot first.