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12-string acoustic intonation


Northstar

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It's really a tough situation because the different string guages need slightly different compensation and that's hard to carve into a saddle with the strings right next to each other. I tried once and gave up after ruining a bridge. There are ways you can tune a 12 string that keep things in tune if you play high up the neck. Basically fretting things up there and creating harmony...and then tuning open strings....and then finding a happy medium between the two.....but no intonation system is perfect.

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A 12 can be properly intonated exactly as a 6 (or an electric, for that matter), by adjusting the break point of each string of each course. When Bryan Kimsey reset the neck on my D12-28 he did it, when I built my OM12-42 I spent 6 hours working with the saddle until I was satisfied (use the same method as you do on a sixer - get the action as low as you want it, put a little piece of wire - a B string works - on top of the saddle and move it back and froth until the fretted 12th and harmonic are as close as you can get, mark and fiile). Both guitar play very much in tune up the neck, but the saddles look a bit like a ripsaw blade. Obviously, the higher the action, the more the strings will play sharp, unfortunately many 12's have pretty high actions.

 

Since Taylor can cast their Tusq saddles (and cnc mill them), they do this on at least some of their 12's - I know the T5-12 has a factory made compensated saddle. And since most people really don't play a 12 way up the neck it is kind of wasted effort for them. But I happened to see a picture of Leo Kottke's 12 a few weeks ago and sure enough, the saddle looked like a saw blade.

 

I'll add that I saw a picture of an old D12-20 in a recent Fretboard Journal with a 1/4 inch wide saddle to allow it to be compensated and I know that Todd at Fraulini guitars does the same. (btw, if you want a copy of Todd's pdf on how to setup and intonate a 12, shoot me a PM with your e-mail addy)

 

And as GuitarCapo points out, properly tuning a 12 can help even out the differences between strings and courses - just one of the problems of our little equal temperment boxes. I use my Strobe tuner on my 12's (as well as for compensating the saddle as I describe above), it has the ability to temper the tunings (but I find I don't need to).

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My Hohner never had good intonation. But it's main playing days were when I was younger and didn't know what I know now. I would always have to tune it slightly differently based on whether I was playing a song in G or E, for example. The Hohner doesn't have a compensated saddle so that is the core reason for the problems.

 

My Yamaha, being much newer, has a compensated saddle and tuning it with my Korg GA-30 tuner, the only adjustment I need to make is to the B strings. I compare them fretted at the 3rd fret to the open hi D string and then compare them open to the A string fretted at the second fret. With just the tuner, it doesn't sound quite right, but after the adjustment, every chord sounds right. And the adjustment is very minute.

 

There is a little difference between the open string and the 12th fret harmonic but for the overall pitch of the guitar, it is practically perfect to my ear. I know it could be improved, and I will have it worked on a bit in the near future, but it's pretty darn close out of the box for a $300 12-string.

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I wouldn't have thought your average saddle was thick enough to adjust the break angle for all twelve strings. I've got a Danelectro DC12 electric which has 12 adjustable saddles. After setting the intonation on a strobe tuner I was amazed at how different the saddle positions between each pair of strings, a much wider margin than any acoustic saddle is able to achieve.

 

I guess acoustic 12 string tuning is much more of a compromise than that of a sixer.

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I wouldn't have thought your average saddle was thick enough to adjust the break angle for all twelve strings. I've got a Danelectro DC12 electric which has 12 adjustable saddles. After setting the intonation on a strobe tuner I was amazed at how different the saddle positions between each pair of strings, a much wider margin than any acoustic saddle is able to achieve.


I guess acoustic 12 string tuning is much more of a compromise than that of a sixer.

 

 

Pretty much true, here is a crappy picture of my D12-28 saddle. Note the pins turned around - the bridge has been slotted and ramped, which, IMHO, is a good thing to do to a 12 string

 

IMG_1440.jpg

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Freeman, what is the advantage of turning the pins around? I've never heard of that.

 

 

Jd-drafter turned you on to the link. Two things are going on here - first, I SLOT the bridge all the way thru the plate so the string comes up in the slot in the wood, not the pin. I is felt that this give better contact on the bridge plate and less wear. Since the slot in the pin is no longer necessary you can turn them around or use unslotted pins.

 

Second, and important to a 12, is that I RAMP the exit of the slot to try to get as close to a 45 degree break angle on all strings to maximize the tension on the top. The back pins on a 12 usually have very shallow break angle and since these are usually the primaries, I try to make that angle as steep as I can. It doesn't show real well in the picture but the ramps run up along side the octave pins. Slotting is also what sets the spacing of each course - you can kind of fudge the slots to make the strings closer or farther.

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