Ibanez archtop with 0.010 Thomastik strings and rosewood bridge intonation issues

[Keru]

Hey guys, first post

So I recently bought a Ibanez GB10EM that came with 0.011 gauge strings.
I asked a luthier to make a new bone nut and to custom fit the floating wooden bridge to the top, aswell as to change the string gauge to 0.010 (Thomastik).

I'm now having issues with intonation even if the open string and 12th string harmonic match perfectly.

The saddle is fully rosewood and is now angling towards the nut (I dont know if this was done on purpose). I've seen people install TOM saddles to compensate for these intonation issues but I dont know if that's going to add more weight to the guitar ( I'm trying to keep it light as I can).

I dont know if the change to a lighter gauge is causing the problems and if the tension of the strings are enough to keep the bridge in place.

Would love to read your inputs on this

[DanielleOM]

I usually compare the fretted 12th fret note to the 12th fret harmonic. I do understand there are other methods. What do you find when you compare using that method. If I have to choose I find a 12th fretted note that is slightly flat is more tolerable than one that is sharp.

I will look forward to seeing what other responses you get. I normally find the TI strings to work well with archtop bridges from an intonation point of view.

[teeps]

The open string and 12th fret harmonic will always be in tune with each other. The 12th fret harmonic should also be in tune with the same string fretted at 12th fret. Is that the case?

[RJVB]

Would love to read your inputs on this

Yeah, can you post a picture or two of the bridge/saddle so we know what we're talking about? If you mean that the saddle is *leaning* towards the nut that is not normal and can indeed cause intonation problems (in addition to structural ones if you let it perdure).

I just replaced the ebony bridge + saddle on my Loar with a bridge/saddle assembly that has a bone insert (I'm guessing you're using something comparable). I use much heavier strings, but intonation is spot-on despite the high action and relief that I dialed in. I use much heavier strings than you, but a priori it should be possible to adjust the saddle position so extra-lights intonate correctly too.

One more remark: such light strings will go sharp more easily than heavier ones by just pressing too hard or pulling them sideways. I assume you took that into account (?).

[Bebop Tom]

Do those strings have an unwound third? That could be a problem with a wooden saddle made for a wound third set.

[RJVB]

Ah, yes - and the reverse can be true too; sets with a wound 3rd intonate a lot better on saddles that have obvious micro-compensation with the contact point for the 1st and 3rd strings at the same distance from the nut (with the saddle parallel to the nut).

[Keru]

Heeey, was on a trip this past weekend sorry for not replying sooner.

The last 3 strings (E,A,D) are ever so slighty sharper in the 12th fret, while the first 3 (G,B,e) are in tune.

So I would have to move the bridge only in the bass side? seems kinda hard to do, especially if you dont want the treble side to change at all.

Here are some photos of the nut and bridge, also an overall of the guitar. I asked to change the pickguard holder for a Gibson one - the stock one pierced trough my leg sometimes when playing while sitting.

The Thomastik strings has a Wound G.

I feel that the bridge pickup has a slight angle towards the pickguard, because of this change of the holder, it make the pickguard much lower that with the stock holder.

Also CTS pots. Because

Thanks

[sgosnell]

Those nut slots look to be very high. That will adversely affect intonation and playability. The strings should come off the nut at near the same height as the first fret, and that looks to be near twice the string diameter for the bass E string, and even more for the treble side. It may be parallax, but both views seem to show strings that are much too high above the fretboard at the nut. I think you need a decent setup on the guitar. You will never find a guitar straight from the factory with satisfactory nut slots.

[Keru]

Those nut slots look to be very high. That will adversely affect intonation and playability. The strings should come off the nut at near the same height as the first fret, and that looks to be near twice the string diameter for the bass E string, and even more for the treble side. It may be parallax, but both views seem to show strings that are much too high above the fretboard at the nut. I think you need a decent setup on the guitar. You will never find a guitar straight from the factory with satisfactory nut slots.

This nut was made from bone by the luthier. So your opinion is to make him review the nut? How can I be sure? When I get home I'll check if the notes on the first fret are in tune - I think that would be a symptom of a "high" nut?

Thank for the reply

[RJVB]

The action at the nut does look a little high but it's hard to tell given the angle and without knowing how high your frets are. 2 ways to check the nut slot height and its effect on intonation:
1) check the intonation at the 1st, 2nd and 3rd fret with the open string in tune and using a precise tuner. Too high nut slots mean those frets will intonate sharp, something you'll probably hear easily enough at the 2nd fret of the 5th, 4th and 3rd strings.
2) hold down a string at the 3rd fret and check the clearance between it and the top of the 1st fret. It should be really low, low enough that you hear just a faint "ping" when you tap the string down onto the fret.

But action at the nut usually has very little effect on the intonation at the 12th fret, where your problem lies from what I understand. Does the intonation error become worse when you go higher? If so, an easy thing you can try yourself is to use the thumbwheel on the bass side to lower the saddle little by little (keep track of how much you turn that wheel), until you start to get fret buzz. Check the intonation. If improved, raise the saddle just enough to get rid of the fret buzz during normal playing. If not, you can just as well return it to the original height. And then you'll have to pivot the bridge a bit around the point under the 1st string's slot, moving the bass end backwards. Drop the tension of at least the wound strings for that a bit to make it easier. You can check the intonation with the 6th string at that lower tension until it seems OK, then retune and re-check.

There's a small chance that some strings will intonate flat in your case, when the 2 E strings intonate correctly. That's usually less noticeable than strings that intonate sharp: we hear it less well (aka somewhat flat notes stand out less than somewhat sharp ones) plus it's easier to compensate by pushing a bit harder or "bending" just as much as necessary.

[sgosnell]

The intonation can be set at the 12th fret however high the nut slots are. But the notes at other frets, especially the ones nearer the nut, will be out of tune. As I said, the issue might be due to parallax, and the slots may be better made than they look in the photos. It's very difficult to judge from photos only. The main issue for me with high nut slots is that it's hard to play and to get action that's low enough for my taste.

The bridge can be moved on one end only, but it does require finesse. It usually takes me a few adjustments to get mine set right. You should also know that it's difficult, if even possible, to get all the strings to intonate perfectly at the 12th fret. The lower the action, the easier it is for me. I tend to set the bridge so that the A and B strings intonate, and the rest do what they do. Some prefer to intonate the outside E strings, but I find the rest of the strings are marginally closer when the A and B are correct. It is difficult to adjust the bridge when the strings are at pitch, but it is possible. A common method is to loosen all the strings except the two used to set the intonation, because it's much easier to move the bridge with only two strings at tension.