Intonation issue ~ string gauge related, or what else ¿?¿

ChrisMusic · November 2016

I would really appreciate a little help here...

I have a Dreadnought which is more or less OK on the 1st string, out a little on the 2nd, more or less OK on the third, but wildly out on the 5th and even more on the 6th (all going sharp) at the 12th.

Could this be a string gauge issue ?

The 6th string is also going "dead-ish" or "lacking" and sounding a "bit weird", for want of better words to describe it, progressively from about the 7th fret up.

It arrived with new (I think) strings, but I have no idea what gauge. I certainly don't want to fit heavy ones and risk damaging the top. Neck is straight, tiny relief, minuscule belly-up on the top, guitar is about 15 years old I think.

It is actually a good UK made guitar, so I don't think that the bridge would have been fitted in the wrong place, which was my first thought. The saddle is a single non compensated bar, fitted with what looks like the correct angles.

It is fitted with what I assume is an under saddle piezo, which doesn't seem to work too well with my Sonic Research ST200 tuner, another thing I would like to solve if possible. That is my only tuner btw.

Whilst I am happy working on electrics, I am totally out of my depth with acoustics, so any help guidance or advice would be much appreciated,

cheers,
Chris

Lewy · November 2016

What's the action at 12th fret?

I think a good starting point to the troubleshooting would be to fit a set of fresh strings so at least you can be certain of what's on there and go from there.

AliGorie · November 2016

assuming u have a ‘good’ action at the twelfth fret - do u know how to check intonation ?
hit a harmonic (12th fret) then play the note (fingered) - do this on all strings individually.
e.g. If a note - say 6th string (E) is flat on the finger note compared to the harmonic the compensation is to much on the saddle (the point where the string ‘leaves’ the saddle is to far south and needs brought forward (towards the sound hole and vice versa.
If ya don’t know what all this means do some research to find a ’tech’ who’ll do a decent job.
As u suggest - all this is only relevant for the gauge of string that's on the guitar, but u should be able to get a reasonably intoned guitar with a set of 12’s.
Oh - I don’t trust ‘tuners’ - they tune to math - not music.
Pitch fork for reference note and tune with harmonics = musical tuning.

ChrisMusic · November 2016

Cheers @Lewy ;

Action is what I would call medium, at the 12th fret is about 2mm0 1st string and maybe 2mm75 on 6th.

It is over 30 years since I last bought acoustic strings, and in a small provincial town, that was basically down to Ernie Ball Phosphor Bonze or playing "air guitar" IIRC. And then they used to come off, get boiled up, and restrung, eat-sleep-rave-repeat until they broke !

So I really have no idea what to choose now, and there isn't even a shop to go into around here

I don't do internet shopping either, so I guess that may have to change...

I was hoping that was a decision (and another thread) for another day, but it does make sense, so again any advise isappreciated.

Jalapeno · November 2016

Saddle askew (or back-to-front if removeable type), would be my first thought if action/relief is fine, and it intonates properly (12th fret harmonic same as 12th fret fretted note).

Jalapeno · November 2016

Show us a pic of the nut & bridge/saddle if possible .....

Lewy · November 2016

I'd put a set of D'addario EJ16s (these are light gauge) on. Just about any online guitar retailer sells them. I always use stringsdirect.co.uk but you might want to shop around as their p&p is a bit steep for a single set.

One question - when you say the intonation is out ... are you able to use your tuner to see how much by? It may be that actually it's within what would be considered normal for an acoustic with that action and a non-compensated saddle.

ICBM · November 2016

What make of guitar? Are there any photos online of the same model, or do you have any of it?

It's worth checking the nut height and neck relief, although from the action measurements you've given it doesn't sound like there is a major problem there.

Try a new set of strings first. There is no acoustic guitar I know of that's designed for steel strings that won't take 12s so you should be safe enough with those, but if you're unsure then try 11s.

But it sounds like there could be a problem with the bridge position since even with all those things not adjusted well, it's very rare to find the intonation that badly out.

Some acoustic guitars do shrink along their length as they settle down under the string tension, which brings the bridge forward and will cause this. It's not that common because the design of the top bracing is enough to resist it to a large extent, but it can happen especially if the wood wasn't completely stable when the guitar was made. Hopefully it isn't this, because if so then the only fix is to move the bridge - either by filling the slot and cutting a new one further back, or increasing the width (towards the back only) and using a wider compensated saddle.

For what it's worth I don't usually use a tuner to check and set intonation either - I use the strings as a reference for each other, because that's how you actually hear a guitar when you're playing it - they can be quite useful for solving problems like this because they give you a more accurate indication of how far out it is, rather than just "not much" or "a lot", which can be harder to judge by ear.

ChrisMusic · November 2016

Thanks @AliGorie ~ yes that's how I am checking intonation.

When I played acoustic before, a long time ago, I always used a pitch fork, harmonics and adjust by ear to taste after.

I still do that now with electric, as long as the A is in, and reach for the tuner either to confirm on those infernal days when I just can't get it right, or when I have to retune to concert pitch, or to confirm intonation.

It seems further out than I would expect for a string gauge issue, but then I haven't used anything heavier than 10s on electric, so returning to acoustic, and ~ loving it ~ BTW, is almost a new experience !

ChrisMusic · November 2016

The ST200 is a "strobe" tuner, and has that lovely rotating wheel "light show", great to watch in the dark, and scarily accurate, but doesn't give ± cents reading, which might be useful right now.

Unfortunately I don't have any way of posting pics right now, but the bridge looks about right, angled as I would expect, and the perpendicular is angled towards the sound hole too, nice touch there.

The nut to 12th is slightly longer than 12th to bridge, according to my missus' ropey old tape measure.
**edit: I have now checked with an engineers rule and it appears to be exactly the same, i.e. no compensation at all !

Nut is original, and height is fine, but I have a suspicion that it may be part of the problem. Can the fulcrum point change, or move back a little with time and use?

Subject to how this pans out, I may try a compensated saddle, or recut the pitch of this one slightly.

I would love to get to the bottom of this within the forum, and maybe do any remedial work myself, if possible.

I am sure the wood was well sourced and adequate for the job, the top sounds great with a scratchy fingernail test. I am sure the bridge would have been located perfectly too when it was made. I didn't know that shrink could be a potential problem, so thanks for continuing my education @ICBM, all knowledge is a valuable gift

I have also eMailed the maker, and am still waiting to hear back from him.

ChrisMusic · November 2016

So would I be correct in assuming that this is unlikely to be a string gauge issue ?

AliGorie · November 2016

heres the techie stuff on compensation -
http://liutaiomottola.com/formulae/compensation.htm

ChrisMusic · November 2016

Thanks for the link to an excellent resource @AliGorie , a little light bedtime reading, methinks

Winny_Pooh · November 2016

Check the relief. If there is too much the nut will be physically closer to the bridge and this makes a bigger difference than you would think.

ICBM · November 2016

Winny_Pooh said:

Check the relief. If there is too much the nut will be physically closer to the bridge and this makes a bigger difference than you would think.

I don't think that can possibly make enough difference to be detectable as an intonation problem.

I tried to work out the difference by geometry but I'm too out of practice so I gave it to my teenage daughter to work out

. I did a rough approximation assuming that the neck and strings are two sides of a triangle, which they aren't quite because the neck is curved - and found that with a relief of 2.5mm (which is huge) then the nut will be two hundredths of a millimetre closer to the bridge.

I'll see if she can get the right answer assuming it's a curve...

Jalapeno · November 2016

ICBM said:

Winny_Pooh said:

Check the relief. If there is too much the nut will be physically closer to the bridge and this makes a bigger difference than you would think.

I don't think that can possibly make enough difference to be detectable as an intonation problem.

I tried to work out the difference by geometry but I'm too out of practice so I gave it to my teenage daughter to work out . I did a rough approximation assuming that the neck and strings are two sides of a triangle, which they aren't quite because the neck is curved - and found that with a relief of 2.5mm (which is huge) then the nut will be two hundredths of a millimetre closer to the bridge.

I'll see if she can get the right answer assuming it's a curve...

He said nut to 12th fret is longer, not shorter. Bridge position is wonky, not neck relief, or worse still the scale calculation and fretting is all off .....

What are the distances nut-to12th, and 12th-to-bridge ?

AliGorie · November 2016

not suggesting - but.
there was a guy on a big US forum questioning the QC of a famous Chinese brand, re scale length - 4 pages of advice on what SL was and how to measure it accurately. He started to get stroppy and I mentioned the (center of the fret crown) - he hadn’t a clue - crazy figures he was coming up with.
Eventually it turned out he thought the ‘12th fret’ was the space between the eleventh and twelfth fret ‘Yard Stick’ was correct and he was measuring it correctly - just not measuring the right thing.
If u got a ’standard’ dread - should be a 645 mm SL from the edge of the nut to the (crown’ of the 12 th fret) should be 322.5mm and from the crown (center) of the 12th fret to the saddle (1st E string) should be 322 + a couple or so mm for compensation - note as the strings get ‘thicker’ the compensation gets larger - depending on the gauge of the strings - also note that ‘compensation’ is for the gauge of the ‘core’ wire (mainly).- Look at an electric guitar saddle - the unwound ‘G’ string gets more compensation than the ‘D’ - this is because the ‘unwound G’ is ALL ‘core wire’, the wound ‘D’s’ core wire is thinner than the ‘G’.. Conversely on an acoustic the WOUND ‘G’s’ core wire is thinner than the unwound ’B’ so gets less - is not as far back.

hope I’ve got all this right.

ChrisMusic · November 2016

Yes, I do know the difference

, but not everyone accessing this thread might, so that is a very valid (and somewhat amusing) point to raise here IMO, thanks.

After giving up on my other half's tailor's tape, which apart from being found in the wreckage of the Titanic (probably), looks like it has provided a mini feast for our resident house mouse at some point, so it is a bit too stretchy ! It also only measures to 1/8th of an inch delineations, so moving on...

Old steel engineers foot rule, dodgy eyesight*, and a bit of iteration later...

Nut face (crown?) to 12th crown 321mm
1st string bridge crown to 12th crown 318mm
6th string bridge crown to 12th crown 321mm

so approx 3mm straight line compensation from 1st to 6th strings

To reiterate: 1st string is only very slightly sharp at the 12th, 2nd is sharp, 3rd is almost spot on, 4th is slightly sharp, 5th is quite a bit sharp and 6th is way sharp, unplayably so.

And oddly ? nut face to crown of 5th fret is ≈ 161.4mm and 5th crown to 12th crown is 159.5mm approx

Measurements are as near as I can tell*

Winny_Pooh · November 2016

ICBM said:

Winny_Pooh said:

Check the relief. If there is too much the nut will be physically closer to the bridge and this makes a bigger difference than you would think.

I don't think that can possibly make enough difference to be detectable as an intonation problem.

I tried to work out the difference by geometry but I'm too out of practice so I gave it to my teenage daughter to work out . I did a rough approximation assuming that the neck and strings are two sides of a triangle, which they aren't quite because the neck is curved - and found that with a relief of 2.5mm (which is huge) then the nut will be two hundredths of a millimetre closer to the bridge.

I'll see if she can get the right answer assuming it's a curve...

I've seen it make a difference on my guitars, but then I am more fussy with intonation that most & use the feiten offsets on electrics.

If the fretted notes are sharp then the saddle needs to go back & I have seen reducing the relief help as the increased lower action that results also contributes to a change in intonation.

Mind you, per the latest post If the 6th string is too sharp at the 12th then the saddle needs to be recut. (shaving the nut end of the fretboard could be good too.)

ICBM · November 2016

Winny_Pooh said:

I have seen reducing the relief help as the increased lower action that results also contributes to a change in intonation.

Yes, it's this which is why too much relief causes intonation problems, not the change in scale length/nut position - it's simply because if there's too much relief, you're pulling the strings down further to fret them and hence bending them sharp.

My daughter still hasn't worked out the true change in scale length (maths is not her favourite subject, to be fair…), but it's got to be really close to the approximation with straight lines.

earwighoney · November 2016

ChrisMusic said:

It arrived with new (I think) strings, but I have no idea what gauge. I certainly don't want to fit heavy ones and risk damaging the top. Neck is straight, tiny relief, minuscule belly-up on the top, guitar is about 15 years old I think.

What is the scale length of the guitar? I'd start off with a set of 12-53's to begin with and see how the intonation goes from there.

Another to address which hasn't been mentioned here is if the guitar has acclimatised to your conditions. IMO, a slight change in humidity, whether the guitar is too dry or too wet can significant impacts on intonation - more so with a lighter built guitar, then issues like a nitro, oil, shellac finish would impact this issue.

Then you've saddle and the nut, and if they are looking worn out then an oversized/overhang saddle and a compensating nut could remedy the situation. Chris Alsop makes a few for not a huge amount all things considered, pleased with the nut I bought from him.

ChrisMusic · November 2016

Scale length is a nominal 25.25" according to our dodgy old tape measure @earwighoney .

There are some more accurate measurements for nut >12th > bridge, and also nut > 5th > 12th, for harmonic nodes, in my last post above this one, if that helps your inner Sherlock Holmes. Any and all help is welcome.

Saddle and nut look to be original, and don't appear to be worn. Oversize replacements would give scope for cutting to compensate, if that is whats needed, so thanks for the pointer. Fitting a compensated nut sounds like a good idea, as long as the current positioning is correct.

How would I contact Chris Alsop, should I need to ?

I know precious little about acoustics, so new learning curve for me on this, so much easier sorting intonation on an electric, or is that just my naivety ?

As to acclimatisation, it has moved from Kent to Wiltshire to Shropshire in the last few weeks, and probably been case bound for much of it's life, judging by the lack of fret wear. So that may be an issue, but probably nowhere near enough to cause the intonation problems I've mentioned.

I have no idea what the finish is, very thin, no grain filler, and matt / satin. The mahogany sides look like striped silk, quite beautiful

earwighoney · November 2016

ChrisMusic said:
As to acclimatisation, it has moved from Kent to Wiltshire to Shropshire in the last few weeks, and probably been case bound for much of it's life, judging by the lack of fret wear. So that may be an issue, but probably nowhere near enough to cause the intonation problems I've mentioned.

I have no idea what the finish is, very thin, no grain filler, and matt / satin. The mahogany sides look like striped silk, quite beautiful

12-53's should be fine without any problem for a 25.25" guitar, I'd recommend trying a few different sets of strings first to see if that would provide the intonation remedy.

Do you have access to a decent headstock clip on tuner? If you have access to one, I'd recommend trying to find exactly how much the intonation is out at the 12th fret (percentage of a semi tone). If you've got a problem with the pickup output of the guitar then using a stomp box tuner might not give the most accurate readings.

Also, how wide (thick) is your saddle? Depending on the how wide the saddle is (e.g. 2mm or 4mm), a decent luthier could compensate a new saddle depending on how much the intonation is out (no need for a overhang saddle). That could potentially prevent the need for a new nut as well if the current one is fine.

Here are the links for Chris Alsop's overhang saddle, and compensated nut.

Do you have a humidity meter for you store your acoustic guitar? Soundboards of really lightly built guitars are notorious for moving for changes to humidity issues. I presume is it a very light acoustic guitar? In the first post, the slight belly up issue could be the sign of a slightly over damp soundboard, which could be the problem there and letting the guitar 'dry' could sort it out. Or it could be the saddle needs to come down a bit.

ChrisMusic · November 2016

Cheers for the website details @earwighoney , that looks just like a potential solution

The Intonation Modeller page/app he has looks interesting too. I had a feeling that there would be something like the string end effect meaning that straight mathematical measurements would be a little misleading. I'm not sure if that's the case here. Now I just have to get my head around that effect's affect. Some great resources surfacing in this thread, thanks chaps !

The saddle looks to be about 3mm0. The nut looks and sounds fine, it is just intonation issues which are plaguing me right now. What is it the Paul Reed Smith does to compensate with the nut ? Move it forward or back ?

A deeply compensated saddle like the one you linked too will offset the string in relation to the slot in the bridge, do you think that will have any noticeable tonal affect ? It will also change the break angle, especially as the pins are quite close by. I am not sure if that would be detrimental ? I think that the slight belly is probably just the moment of torque.

I may need to add a clip on tuner to by buy list, any recommendations ? Although right now it would be solely for this task, I guess it wouldn't hurt to have one around.

And that's another no to the hygrometer, I always looked on guitars as tools, but maybe it's time to take a bit more care of them. I take the basic view if it is too hot, cold, wet or dry for me, I wouldn't want my guitar going there either, maybe with the exception of the shower

As to weight, I thought my Blueridge 000 was pretty light when I got it, and it is, but that weighs more than the Dred, and the neck wood on this is a bit dense, so I guess the body must be lightly constructed. I need to get out more ~ at least to play more guitars ! Comparison is probably a good thing, except it will probably lead down the garden path to the lair of the GAS monster, I have seen Lowdens skulking there :o3

ChrisMusic · November 2016

Any more answers or insights to any of the points / questions raised ?

Also while I am here, is there a simple resource for checking the fretting ?

ICBM · November 2016

If you've got new strings on, the relief is OK, the nut height is OK and the bridge height is OK then it's really a certainty that it's the bridge position that's the problem. Why doesn't even matter than much, you just have to find a way to fix it if the problem is big enough that it can't be ignored.

The first thing I would try is a saddle with a compensated top edge, which is fairly easy to make yourself, or you can use the existing saddle if it's slightly too high anyway. You need to cut the top edge into two angled ridges, one running from front to back from the treble end of the saddle to the back halfway between the B and G strings, and the other running from the front at that point to the back at the bass end, like this:

http://www.strangeguitarworks.com/wp-content/uploads/2013/02/IMG_1220.jpg

Although I tend to make the top E position a bit further forward. The more complicated shape you sometimes see on factory-made versions isn't necessary.

(You'd think he could have found some nicer bridge pins!)

If that doesn't do enough you will need to look at the overhang saddle, or widening/moving the existing saddle slot.

ChrisMusic · November 2016

Cheers ICBM, I may just get a blank and some tools and give that a try

I'm not too sure about the two bridge pins being half buried either ! I thought that the ball end was supposed to locate under the bridge, it looks more like it is on the end of the pins from that photo.

The break angle looks rather shallow too, but nicely shaped saddle, so a good illustration from that point of view.

** The reason I am asking about the nut**, if I forgot to mention, is that the intonation across the first few frets is a bit (!) iffy too. Nut groove height is fine though, leading me to think that it may well be contributing to the overall issue, and hence the question about checking the fretting distances and whether the nut is indeed in the optimal place.

ICBM · November 2016

ChrisMusic said:

Cheers ICBM, I may just get a blank and some tools and give that a try

I'm not too sure about the two bridge pins being half buried either ! I thought that the ball end was supposed to locate under the bridge, it looks more like it is on the end of the pins from that photo.

The break angle looks rather shallow too, but nicely shaped saddle, so a good illustration from that point of view.

** The reason I am asking about the nut**, if I forgot to mention, is that the intonation across the first few frets is a bit (!) iffy too. Nut groove height is fine though, leading me to think that it may well be contributing to the overall issue, and hence the question about checking the fretting distances and whether the nut is indeed in the optimal place.

Yes, everything about that pic is a bit dodgy, except for the very nicely shaped saddle

.

What happens to the overall intonation if you capo it at the first fret, tune it accurately (F-F) and then check the intonation at the 13th fret?

That would eliminate (or confirm) the nut as part of the problem, even if there is another problem at that end.

ChrisMusic · November 2016

Capo ~ wazzat ???

I thought that was what my index finger was for !

Of course you are right, another thing for my to buy list then, and probably will only be used for this one task.

So is there another simple (& quicker) solution to save buying one ? (apart from the maths that is)

Thanks for your help once again, much appreciated.

ToneControl · November 2016

ChrisMusic said:

Capo ~ wazzat ???

I thought that was what my index finger was for !

Of course you are right, another thing for my to buy list then, and probably will only be used for this one task.

So is there another simple (& quicker) solution to save buying one ? (apart from the maths that is)

Thanks for your help once again, much appreciated.

try this:
tune the strings open
check the tuning for the first 1-3 frets on each string
I think this should tell you if the nut is cut badly

ICBM · November 2016

ChrisMusic said:

Capo ~ wazzat ???

I thought that was what my index finger was for !

Of course you are right, another thing for my to buy list then, and probably will only be used for this one task.

So is there another simple (& quicker) solution to save buying one ?

A pencil and an elastic band

.

You will need to double (or triple etc) the band to get enough tension, loop it round the pencil about halfway along, put the pencil across the neck with the end only just overhanging on the other side, and then hook the band on. A faff but it can be done. Worked for me at a gig when I forgot my capo!

It will cause much more serious tuning problems than a proper capo, but that isn't actually an issue for this purpose since you'll be retuning as precisely as possible anyway.

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Intonation issue ~ string gauge related, or what else ¿?¿

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