Intonation woes

I recently got my MD-315 set up because the action at the nut was FAR too high (to the point where I was really badly hurting my finger). I'm happy to say that's no longer an issue, but am fairly disappointed with the setup: The bridge may be a bit too low now (a bit of buzzing on the G string), the bridge intonation seems to have been way off, and the G string is slightly sharp at the first few frets (but actually a bit flat higher up). I have two questions:

• Is it possible my G string nut slots are too high? (see picture below, not sure if it's a good enough picture to tell). I've half a mind to learn how to do this adjustment myself if I need to...
  
• I have a general sense for how to adjust intonation at the bridge, but it's a really annoying process - I have to loosen the strings a lot to move the bridge at all, but I have to re-tighten them to check the intonation, which takes a long time and I feel like puts a lot of strain on the strings. Do you have any tips for speedy bridge intonation adjustments?

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Originally Posted by TonyEarth

...Do you have any tips for speedy bridge intonation adjustments?

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I have methods, but I wouldn't call them tips because they took a while to learn and can be dangerous to the instrument if done by someone inexperienced.
My tip would be; take it to someone good at mandolin set up. If you are one of the unfortunate people who don't live within reasonable driving distance of someone good at mandolin set up then my tip is unfortunately of no particular use.

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Originally Posted by sunburst

I have methods, but I wouldn't call them tips because they took a while to learn and can be dangerous to the instrument if done by someone inexperienced.
My tip would be; take it to someone good at mandolin set up. If you are one of the unfortunate people who don't live within reasonable driving distance of someone good at mandolin set up then my tip is unfortunately of no particular use.

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Heh, well I appreciate it nonetheless. Unfortunately that's what I thought I did that put it in its current state, they were pretty well recommended and are sort of the only person near me. I'm moving cities soon though, so I'll check out what the options are there.

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Originally Posted by TonyEarth

I recently got my MD-315 set up because the action at the nut was FAR too high (to the point where I was really badly hurting my finger). I'm happy to say that's no longer an issue, but am fairly disappointed with the setup: The bridge may be a bit too low now (a bit of buzzing on the G string), the bridge intonation seems to have been way off, and the G string is slightly sharp at the first few frets (but actually a bit flat higher up). I have two questions:

• Is it possible my G string nut slots are too high? (see picture below, not sure if it's a good enough picture to tell). I've half a mind to learn how to do this adjustment myself if I need to...
  
• I have a general sense for how to adjust intonation at the bridge, but it's a really annoying process - I have to loosen the strings a lot to move the bridge at all, but I have to re-tighten them to check the intonation, which takes a long time and I feel like puts a lot of strain on the strings. Do you have any tips for speedy bridge intonation adjustments?

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It is impossible to judge your setup from the pic. You can fret the string at 2nd fret and notice gap between the string and first fret, ideally it would be zero (meaning the nut slots are at the same level as frets, assuming all the frets are level to start with). I personally prefer barely visible gap for e and a strings and slightly larger for D and G, it makes chops in low position (B, E or C chords) a bit clearer...
Bridge height can be personal thing, I like medium action and when I get really heavy handed I get buzz especially on G, that's normal. You can adjust the bridge easily with the thumbwheels and such fine adjustment wouldn't require you to move it for intonation.
The problem with intonation could as well be built in your mandolin if your first frets are sharp and higher frets flat it can be high nut slots, but it would have to be way too severe. More likely the fretboard was cut a bit too long at nut end making the space between 1st fret and nut longet than it should be. This will make your notes sharp, you can adjust bridge position to reduce this but never down below 5th or so fret or the high positions will be unbearably flat. You can measure the fret positions and find out if this is athe case.
Intonation can be pretty easily adjusted with just one string of each pair loose and other tuned to pitch. It is easy to move bridge and adjust height with four strings only... I often use wax on underside of freshly fitted bridges to prevent sticking to fresh or soft finishes as well as it makes sliding the bridge a bit easier.

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Originally Posted by TonyEarth

[*]Is it possible my G string nut slots are too high?

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Yup..and very likely indeed. I saw way too many instruments (even from factories) set up with not-quite right nut slot heights. It messes up all the other tuning adjustments so no matter what you do to the bridge height or overall compensation, the intonation is off because frets 1-3 or so are sharp.

After the frets were leveled and smooth, I always set up the nut slot height before I adjusted the bridge height nor scale length. So far it's worked on everything fretted from bass guitar to mandolin.

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Originally Posted by HoGo

More likely the fretboard was cut a bit too long at nut end making the space between 1st fret and nut longet than it should be. This will make your notes sharp, you can adjust bridge position to reduce this but never down below 5th or so fret or the high positions will be unbearably flat. You can measure the fret positions and find out if this is athe case.

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I have dealt with this on my instruments, and I understand some makers shorten the fingerboard. I speculate the cause is not too-long fingerboard but the behavior of the string bending over the nut. Between frets the string deflection angle changes only slightly, but from nut to first fret is a large bend, and it changes the direction of the bend when you fret. After shortening my fingerboards they play beautifully in tune in those low frets, but the distance between nut and fret 1 looks too short. The strobe tuner proves my ears are correct in hearing it play in tune.

The challenge is finding a luthier to do this for you, as it will involve a new nut and/or shim behind the nut. I did it myself but I am too impatient to be without my axe for weeks. In my case, I found shortening the distance to 1st fret by about 0.010" worked fine.

The Person strobe tuner app costs like $9, and there are other high-resolution tuner apps. Get one and test the low frets.
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Uneven-height pairs are another challenge to play in tune, but that is tested by playing response and visual examination of them at the nut.

Bridge position adjustment in a nut shell:

1. Loosen all the strings 4 or 5 turns except for the outer E and outer G strings.
2. Adjust the bridge position using a good quality tuner, checking the fretted note at the twelfth fret against the harmonic, and also the open string. Start with the G.
3. Move the bridge foot towards the fingerboard to sharpen the fretted note, or towards the tailpiece to flatten it. Make sure the bridge is still standing up straight.
4. Repeat the process with the E string.
5. Double check as necessary until the intonation is good on both strings.
6. Tighten the rest of the strings gradually. The bridge may try to lean forward. If it does, tip it back into position and tighten some more. You may have to tip it back into position 2 or 3 times.

This will get you into the ballpark. I use a more complex process.
If you still have problems with it, change the strings and repeat. If that doesn't take care of it, you'll have to find a better repairman.

Yes, it is possible the nut slots on the G's were left too high. Or the slots might not have been angled correctly. In either case, fixing it requires the right files and plenty of experience. I often see people try to adjust nut slots themselves, and get the slots too low. You don't want that.

Chances of a recent issue Eastman fingerboard being cut too long are pretty small. The factory has high precision cutting tools. And if it were too long, I would expect you to have at least some problems on all the strings.

OK, now you’ve done it! What is the more complex process?

I check a number of different intervals between adjacent strings and position the bridge so everything is in reasonably good temper. I check major thirds, perfect fourths, perfect fifths, and octaves. Sometimes I have to do a little filing to adjust the compensation of one or two of the string sets on the saddle. I do it all by ear. That's the gist of it.

It requires a very good ear, a fresh set of strings, and plenty of patience. If I tried to write it all down, it would be an unintelligible mess.

If the string is sharp at the first fret or two but flat ass you fret up the board that is a good indication the nut is cut high. About the only other thing that would cause that would be poorly placed frets.

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Originally Posted by Nevin

If the string is sharp at the first fret or two but flat ass you fret up the board ...

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That is my favorite typo I have seen in a while :)

Or Nevin is one devious jokester!

Nope, just tired and a poor proof reader. Carry on.

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Originally Posted by rcc56

I check a number of different intervals between adjacent strings and position the bridge so everything is in reasonably good temper. I check major thirds, perfect fourths, perfect fifths, and octaves. Sometimes I have to do a little filing to adjust the compensation of one or two of the string sets on the saddle. I do it all by ear. That's the gist of it.

It requires a very good ear, a fresh set of strings, and plenty of patience. If I tried to write it all down, it would be an unintelligible mess.

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Or the use of a good tuner to check pitches at all of these locations.