Acoustic guitar intonation

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Monkey Allen

Monkey Allen

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Hi...I have a question about acoustic guitar intonation...but first some background...

I own a Taylor 110 and a Martin DX1...basically in the level just above cheapskate when it comes to buying guitars. Sometimes I really want to smash them because they have intonation and tuning problems. The low e will be sharp at the 12th compared to open...the b string will be the same.

Anyway...correct me if I am wrong...if there is a discrepancy between the pitch of the open (let's say e string) and it's fretted octave at the 12th...then there is a different string length from 12th to saddle and between 12th and nut. To correct this you must adjust the distance so it is even.

I heard that the technique is to reseat the saddle...but my question is...what if you have more than just the low e string that has a dodgy length? What if when you reseat the saddle to fix the low e, suddenly the b string is out of whack? Then let's say you go back and fix that...then the e string is out...possibly the g string...etc?

I'm lead to believe that the 12th fret should mark the exact midway of the string...but how can that be when saddles are not uniform...they are set back and forth per string.

Where does string height come into play?

If I string my guitar with a size string that the manufacurer says are not recommened, have I hurt the intonation?

Why when I take my guitar to be set up does it come back as thuogh the tech never touched it? Well that's probably because he didn't....which is why I want to learn it myself.

So anyway...any links or advice would be great. Thanks.
 
The string length on an acoustic or any fretted instrument for that matter will not be exactly twice the octave (12th fret). That is why saddles are compensated. There has been a lot about this in the past so search the forums.

A few extra questions. How far out of wack is the tuning on both the low E and High E? What method are you using to tune you guitar? What gauge strings and what action do you have?

Then read this and this and com back and lets us know which bits are not clear to you and a few more specifics of the problem you have.

Essentially what you have to understand is this. Tuning a guitar is a compromise and not a perfect science. The saddles are compensated to accommodate the effect of extra tension in the string as a result of fretting and the compromise of modern tuning systems. In particular 12 note equal temperament (12ET). If the issues you are having go beyond this then we need more specific info to give more specific answers.
 
Don't start me on "B" strings...

You'll be pleased to know that these issues happen in expensive guitars too! I don't think I've ever had an acoustic guitar that's been perfectly intonated, and it's usually the low e and b that are the worst.

It gets particularly noticable if you play high frets a lot like I do and you have one string going out sharp and the string next to it going out flat as you move up the board..

As Muttley says, it's always a compromise...
 
Thanks, I'll read those ilnks soon.

I mainly play open chords...and it really gets me when a G is sounding ok...then the C sounds...well it sounds like I want to smash the guitar into a million pieces.

I put in a new saddle a little while ago...a Martin one (my Taylor is home in Australia) in my Dx1...I put it in to lower the action. I'd say that's done something to mess with the intonation a little...but the strings are lower now...and that's good.

I just need to get the intonation a lot closer...compromises yes...but I hate having to compromise so much that I'm scared to pick up my guitar because I know it's going to sound like shit every time.

Anywa...I will read and get back
 
Monkey Allen said:
Thanks, I'll read those ilnks soon.

I mainly play open chords...and it really gets me when a G is sounding ok...then the C sounds...well it sounds like I want to smash the guitar into a million pieces.

I put in a new saddle a little while ago...a Martin one (my Taylor is home in Australia) in my Dx1...I put it in to lower the action. I'd say that's done something to mess with the intonation a little...but the strings are lower now...and that's good.

I just need to get the intonation a lot closer...compromises yes...but I hate having to compromise so much that I'm scared to pick up my guitar because I know it's going to sound like shit every time.

Anywa...I will read and get back
Click to expand...

OK to start with read this one. Then read the others.;)
 
Thanks the links are helpful and with the temperate tuning methods I can get a more satisfying end result for strumming multiple open and barred chords...however...I still badly notice the low E and the G string to be making an open E chord a nightmare and the open G is not what I would like it to be. C, D, F, Am and many other sound ok. In fact D and C are very nice. Buty E is quite terrible because the low e string and the g string sound poor.

My guitar plays open chord C beautifully now.

Does that tell me that I should focus on some kind of physical adjustment for those 2 strings?

Or do I just settle for the advice in the links..."put up with it", "learn to ignore it"?

I supopse I could learn to play this shape instead of a natural open e chord:

0
0
4
2
2
0

Sounds better than open...maybe I just work around the problems
 
Out of curiosity...after watching a youtube video where some fella was talking about how the distance between the nut and the 12th fret should be the same as the distance between the bridge and the 12th fret...I got a tape measure and checked my Martin D28.

I expected some difference...but from bridge to 12th (this is just for the bass E string) it is about 32.4cm

From 12th to nut it is about 31.9.

I was pretty amazed by that. So I had some questions:

1. Where exactly on the bridge do I start measuring from? Is it the spot where the string connects the bridge? Or is it back at the peg?

2. Where do I measure the 12th fret? Is it ON the actual 12th fret or is it in the middle - the fingering area?

3. Where exactly on the nut should I make my measurement?

and finally...

4. The 5mm difference...is it a lot in the scheme of things?

I've never had this guitar set up at all...and since day one it has been a bit unbalanced, I have suspected.

Further info...High E string:

Bridge to 12th = about 32cm
12th to nut = about 32.1/ 32.2cm

This is a lot closer than the bass E string.

Further further info...the way I measured is from string connecting area on bridge to the actual 12th fret....and the actual 12th fret to the beginning of the nut...

thanks if you can fill in any details about what I should do or any of your experiences.

Guitar's a 2009 model...maybe 2008
 
Measure from the body side edge of the nut to the center of the actual fret, and the center of the fret to the neck side edge of the bridge.
How worn is the neck of the guitar? If the fingerboard has a depression (from use) where you press a string down, then you are stretching that string more and it will sound sharp compared to the other strings.
 
Ok...I took those measurements too...and there is an even more stark difference between the two measurements...on the bass E string. Right now I don't have the numbers but will post later.

The guitar is virtually brand new...no wear...no tear and no...obvious damage...but..

It's been on a plane in the regular luggage section (for an 8 hour trip)...it's experienced a few humidity changes within the past few weeks. I bought the guitar brand new last August.

btw...when you say bridge...where exactly? Do you mean the wooden part of the bridge or the plastic/ bone saddle on which the strings sit?
 
mjbphotos said:
Measure from the body side edge of the nut to the center of the actual fret, and the center of the fret to the neck side edge of the bridge.
Click to expand...

I've done this exactly:

nut to middle 12th = 31.1cm
middle 12th to bridge = 32.5

At least for me...this is pretty alarming. Is that a huge difference or what?

I bought this guitar in August '09 and have taken impeccable care of it...aside from it's 8 hour plane flight and some humidity fluctuations over the past month.

From about Sept '09 to March 2010 it existed in around 70% humidity.

I look down the neck...it appears straight...now bows or warps...

I'm out of my depth in analysing this any further myself...all I can imagine is that maybe I got a lemon...and that's got to be some lemon coming from Martin USA with a D-28

Any thoughts?
 
I would just like to highlight this sentance.
muttley600 said:
The string length on an acoustic or any fretted instrument for that matter will not be exactly twice the octave (12th fret). That is why saddles are compensated.
Click to expand...
If you are using the 5th and 7th fret harmonics to tune the guitar, it will always sound like crap. You need to read those links from Muttley before anything else. Especially this one. http://www.stagepass.com/tuning.html

Put down the tape measure and start reading.
 
That article doesn't refer to the length of the string from nut to center 12 to bridge. Anyway I always wondered what this guy was on about with his equidistant spiel...because that saddle is on an angle...so there's no way the nut to center 12 to bridge could ever apply...you'd have to have an angled nut too...anyway this guy I saw on youtube...old guy...distinguished...workshop full of pro tools and a website qualifying him as some kind of luthier...what's he saying this for?

On another note...when your open E string is struck and sounds on pitch...but at the 12th fret the plucked E note is either flat or sharp...what does that indicate? What is the problem with the guitar in that case? And what can be done to fix it?
 
Monkey Allen said:
That article doesn't refer to the length of the string from nut to center 12 to bridge. Anyway I always wondered what this guy was on about with his equidistant spiel...because that saddle is on an angle...so there's no way the nut to center 12 to bridge could ever apply...you'd have to have an angled nut too...anyway this guy I saw on youtube...old guy...distinguished...workshop full of pro tools and a website qualifying him as some kind of luthier...what's he saying this for?

On another note...when your open E string is struck and sounds on pitch...but at the 12th fret the plucked E note is either flat or sharp...what does that indicate? What is the problem with the guitar in that case? And what can be done to fix it?
Click to expand...

The reason the distance from the 12th fret (or any fret for that matter) needs to be made longer than the theoretical length is to accommodate for the extra tension you put in the string by fretting it. The pitch of a string is dependant on it's length, it's mass per unit length and the tension. Change any one of those and you change the pitch.

If the pitch at the 12th fret is sharp or flat in relation to the open string there are a number of options for correcting it. If the setup is correct with the action as it should be, the neck relief adjusted correctly and the nut fitted correctly then the only way is to move the saddle forward or back.

Read the articles that I linked to originally, it's all there.
 
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