Question about bridge placement

I understood that the bridge was supposed to be installed at an equal distance from the 12th fret as the nut is to the same fret. I just noticed that mine is actually almost 0.5 inch closer to that fret than the distance from the nut.

I had taken it in months ago to have a shop check the stock nut as I thought it was having issues and they put a replacement nut on it....but I never really checked it this close. I am a beginner and still figuring this stuff out.

However, it did feel like I had less room to pick before hitting my fingerboard extension [going to get it scooped]...and finally decided to measure.

I am thinking about moving it back myself as a good exercise on bridge placement and getting the intonation correct...just thought I would ask the group for some advice and comments.

Check the intonation before you move it. It should be positioned approximately so that the 12th fret is 1/2 way between the nut and bridge. I will not be exact, but 1/2" does sound quite a bit off.

Go to stewmac.com and search for their fret calculator. It will tell you the proper distance from nut to bridge. However, it will ask for the scale length and you might have to guess since your bridge has been moved. Chances are your scale length is 13 7/8. Try that and then check the distance on the first few frets to confirm.

No need to measure, although measuring may give you a good starting point. The real goal is proper intonation. If the note played at the 12th fret is sharper than the string open, move the bridge toward the tailpiece. If the 12th fret plays flat, move it toward the fretboard. Make small movements until the 12th fret octave plays in tune. You will want to have the strings tuned down a fair bit so that the bridge will move more easily under the lower tension. Also you really only need to check this with the G and E strings, unless you feel like messing with your bridge compensation...

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Originally Posted by Chuck D

... it will ask for the scale length and you might have to guess since your bridge has been moved. Chances are your scale length is 13 7/8.

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The term "scale length" always used to confuse me, considering that compensation at the bridge cause no two pairs of strings to be EXACTLY the same length. Heck, on a guitar the saddle is angled off by maybe 1/4 inch at the ends, so how can Martin (just as an example) claim a 25.4" sale length?

But apparently, the technically proper definition of "scale length" totally ignores the position of the bridge & saddle:
- "Scale length" is, simply, twice the distance from the nut to the 12th fret.
That allows the placement of the bridge (saddle) to vary as needed based on the player's preferred string height and string gauge.

To the OP: The distance from the 12th fret to the bridge (saddle) has to be slightly MORE than the distance from the 12th fret to the nut because the simple act of fretting (at 12 or elsewhere) stretches the string, thus raising its pitch slightly from what you'd expect based on length alone. How much each string must be lengthened is called "compensation", and THAT topic could fill a whole book. But I suspect that the Frets.com website addresses it fairly well.

0.5" closer is way off: as others have said it should be slightly further from 12th fret to bridge than from nut to 12th fret. Sounds like someone set the intonation on the 11th fret rather than 12?

The correct placement of the bridge is something any player needs to learn to do on his/her instrument. Were you more experienced you would have noticed it was not positioned correctly sooner.... So now is the time to learn.... and practice so that there is no reason for the bridge to ever be off. It is your responsibility as a player...

Thanks for all the input. I figured, hey maybe this is my opportunity to learn how to set my bridge placement and check for intonation accuracy in the process. Its just one of those things that I am sure comes with experience and some level of comfort and knowing your instrument.

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Originally Posted by Alan Lackey

... maybe this is my opportunity to learn how to set my bridge placement and check for intonation .....

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You bet it is! Scroll down to "Basics of Archtop Guitar Setup", under the Acoustic Guitar heading. Archtop mandolin is similar, just a bit smaller.
http://www.frets.com/FretsPages/pagelist.html#Musician

Be forewarned: Despite the temptation, reading this website from end-to-end could take several weeks!