Acoustic Guitar Construction

The tweaking the intonation on a new guitar depends on many factors -- foremost is the realization that the instrument is going to "settle in" over time -- string tension is going to shape the neck and of course the sound-board. Then there is the total tension of strings selected -- gauge and brand. As explained in the article below it takes a little time and experimentation to match strings with your guitar and for the instrument to stretch a bit and sometime shrink (humidity). So the point is don't get all wrapped up in the formulas you might have seen on the internet or elsewhere -- make a saddle that will get you in the ball park and be aware that it may be possible to make improvements a little down the road.

http://www.kennethmichaelguitars.com/saddle.html

That is great info I cant wait to get to that point. Always look foward to your seeing your posts.

Though magic fairy dust (MFD) would be welcomed as well. :-)

There's something about intonation that I don't quite understand. Someone tell me the fallacy of my thinking. If an open note is in tune and the fretted 12th note is sharp, the standard procedure is to lengthen the string at the saddle. That makes the fretted 12th note in tune but makes the open note flat because the string is longer. To make the open note in tune again, the tension of the tuning machine must be increased which makes the fretted 12th note sharp again and we're right back where we started.

No, not if done correctly -- you've made the string longer and therefore changed where the frets contact the full length of the string -- the halfway dividing point (octave) has been moved only in relation to the string toward the bridge -- the section that is played and heard.

On each of my guitars I have at least attempted to intonate the saddle by positioning where the strings break. I have used an electric tuner to match the open note with the fretted 12th note. While working on my current project the fretted 6th strings was sharper than I thought it should be based on the saddle and where the other strings ended up. Before I pulled out the file I played a bit using some information I got from another forum.

The electronic tuner often will lock on a partial instead of the fundamental. Where the string in picked can influence which of the partials are the strongest. Based on different body resonances the partials could be pushed off a bit from the fundamental. The suggestion I used was to tune the open string picking at the 12th fret. I was surprised at the difference. Also I recently picked up a Peterson tuner with a mechanical strobe. With it I could see some of the partials at slightly different frequencies. I was a bit intimidated at first with all of the swirling rings, but I finally got the concept of tuning the large ring (lowest frequency) that would tune. That way I was tuning the fundamental frequency.

It may be the placebo effect, but I also noticed that tuning the guitar with the cheap tuner picking at the 12 fret or using the Peterson instead of the electronic tuner the guitar sounded better in tune as I played.

To close the story, when properly tuning the 6th string it was much closer to being properly intonated than I originally thought, I could have very well de-intonated the string, it I had completely trusted what I was seeing using the electronic tuner.

johnparchem wrote:On each of my guitars I have at least attempted to intonate the saddle by positioning where the strings break. I have used an electric tuner to match the open note with the fretted 12th note. While working on my current project the fretted 6th strings was sharper than I thought it should be based on the saddle and where the other strings ended up. Before I pulled out the file I played a bit using some information I got from another forum.

The electronic tuner often will lock on a partial instead of the fundamental. Where the string in picked can influence which of the partials are the strongest. Based on different body resonances the partials could be pushed off a bit from the fundamental. The suggestion I used was to tune the open string picking at the 12th fret. I was surprised at the difference. Also I recently picked up a Peterson tuner with a mechanical strobe. With it I could see some of the partials at slightly different frequencies. I was a bit intimidated at first with all of the swirling rings, but I finally got the concept of tuning the large ring (lowest frequency) that would tune. That way I was tuning the fundamental frequency.

It may be the placebo effect, but I also noticed that tuning the guitar with the cheap tuner picking at the 12 fret or using the Peterson instead of the electronic tuner the guitar sounded better in tune as I played.

To close the story, when properly tuning the 6th string it was much closer to being properly intonated than I originally thought, I could have very well de-intonated the string, it I had completely trusted what I was seeing using the electronic tuner.

Very interesting.