Bad intonation on one of my guitars.

Construction and repair of Classical Guitar and related instruments
Orcas_
Posts: 17
Joined: Thu Dec 21, 2017 6:07 am

Bad intonation on one of my guitars.

Post by Orcas_ » Thu Jan 04, 2018 9:07 am

My Manuel Rodriguez c1 has pretty bad intonation and I've been wanting to fix the problem if possible. My High E is about 15 or so cents sharp, almost 20 if I put more pressure on the fret at the octave and though it is subtle, my ears can hear it. It's fairly well set up and the tone is nice, although the problem is similar on b and g. Sharp at the 12th on b and sharp on the 12th at G, although on those two strings it's no more than 5 cents sharp so I can't really tell.

I've done what I can, which is changed the break point of the E string and shaped the nut about 1mm which helped the octave sound like an octave, but the higher I play on the E the worse it gets, naturally. At the 19th fret I'm 40 cents sharp already, although I don't really use that fret at all.

I suspect that the bridge was put in the wrong place? The bass strings all seem to be well intonated and I can live with G and B being slightly sharp but that e? Quite a bother to have really. Can I move the bridge back at all? I've tried changing the strings although I stick with med tension and the issue persists. Likely the bridge being a problem rather than a string
is 15-20 cents sharp considered a lot?

Gary Macleod
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Joined: Sat Aug 30, 2014 10:13 am
Location: Edinburgh

Re: Bad intonation on one of my guitars.

Post by Gary Macleod » Thu Jan 04, 2018 9:47 am

Nearly always a bad string. Try a new good quality string, daddario are the most stable in my experience.

OldPotter
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Location: Channel Islands

Re: Bad intonation on one of my guitars.

Post by OldPotter » Thu Jan 04, 2018 11:38 am

15-20 cents is a lot, but if all the other strings are reasonably in tune, then I guess that the bridge is in the right place. If you have already tried replacing the strings, what brand are you using now, did you try to pre stretch the string or do anything different to the top string?
You say you have moved the break point, by adjusting the saddle? And shaped the nut too, by moving it towards the bridge? If you tune the 12th fret to be correct, what do you see on the open string?
Still most likely to be a poor string as Gary says.
"When I was younger, I could remember almost everything, whether it happened or not." Mark Twain

Alan Carruth
Luthier
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Joined: Mon Dec 24, 2007 6:56 pm

Re: Bad intonation on one of my guitars.

Post by Alan Carruth » Thu Jan 04, 2018 5:57 pm

What's the intonation on the first fret? The strings stretch at that end too, and compensating the nut can be an aid in getting the higher frets right. Trevor Gore had much to say on this.

jebejava
Posts: 238
Joined: Mon Dec 18, 2006 7:40 am

Re: Bad intonation on one of my guitars.

Post by jebejava » Thu Jan 04, 2018 6:53 pm

I have a guitar made in the early 1970s which has an intonation problem. The saddle break point is as far back as possible and it still irritates me.

When I measured the scale, I found that there was "minus" compensation - the distance between the 1st and 12th fret is spot on, between 12th and saddle is short.

I am going to fill and re-cut the saddle slot. Everything on the guitar is ok, the saddle slot is just in the wrong place.

simonm
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Re: Bad intonation on one of my guitars.

Post by simonm » Thu Jan 04, 2018 9:08 pm

Orcas_ wrote:
Thu Jan 04, 2018 9:07 am
(…)
is 15-20 cents sharp considered a lot?
This is actually a very strange question. :-)

It is a lot if you can here it and it is the sound of it is bugging you immensely. If the only reason you are bothe is because you have a nice strobe tuner which is telling you the number is high, then it is not a lot.

If it is bugging you, I would say get rid of it. Fixing it will cost way more time and energy than a C1 is worth.

Laudiesdad69
Posts: 1546
Joined: Tue Nov 29, 2016 1:16 pm

Re: Bad intonation on one of my guitars.

Post by Laudiesdad69 » Tue Jan 09, 2018 12:13 am

Orcas_ wrote:
Thu Jan 04, 2018 9:07 am
My Manuel Rodriguez c1 has pretty bad intonation and I've been wanting to fix the problem if possible. My High E is about 15 or so cents sharp, almost 20 if I put more pressure on the fret at the octave and though it is subtle, my ears can hear it. It's fairly well set up and the tone is nice, although the problem is similar on b and g. Sharp at the 12th on b and sharp on the 12th at G, although on those two strings it's no more than 5 cents sharp so I can't really tell.

I've done what I can, which is changed the break point of the E string and shaped the nut about 1mm which helped the octave sound like an octave, but the higher I play on the E the worse it gets, naturally. At the 19th fret I'm 40 cents sharp already, although I don't really use that fret at all.

I suspect that the bridge was put in the wrong place? The bass strings all seem to be well intonated and I can live with G and B being slightly sharp but that e? Quite a bother to have really. Can I move the bridge back at all? I've tried changing the strings although I stick with med tension and the issue persists. Likely the bridge being a problem rather than a string
is 15-20 cents sharp considered a lot?
What is your action on this Guitar? If the action is high, lowering the saddle may help it not play so sharp. It's been my experience, with guitars in this price range, that oft times the bridge is put on in the wrong place. In which case, I would get another guitar.

Also, what strings did you Try? And, are you one of these guys that tunes sharp to settle strings in faster, and do you prefer stretch your Strings? Doing both of those can cause intonation problems.

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Eric Reid
Luthier
Posts: 293
Joined: Sat Jul 18, 2009 9:01 pm

Re: Bad intonation on one of my guitars.

Post by Eric Reid » Tue Jan 09, 2018 5:42 am

Have a luthier you trust check the fret spacing. These can be all over the map on older guitars ( and occasionally on newer builds). I just replaced the fingerboard on a 1963 Manuel Ramirez that had significantly misplaced frets from 12 on up.

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