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12 string intonation
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=12762		 Page 1 of 1
Author:  Andy Zimmerman [ Sun Jul 08, 2007 5:59 am ]
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I had some questions raised about intonating my 12 string.
Here is how I did it.
I use wide 3/16ths saddles. I like to room to work. Also it allows me to make an abrupt drop off at the soundhole side of the saddle and a gradual curve with more resting surface on the bridge pin side.
I use the small wire on top of the saddle technique to find the intonation point and mark it. Then I remove the saddle and use small needle files to file the round over back and drop off front to each line.
I am not quite done yet. The top surface was purposely left a bit fat so I have room to adjust forward or backwards later. I will do this in a week or two.
This is just one way to do it. Personally I think you need to intonate each individual string. Doing them in pairs is just not acceptable to me. In each pair, the higher octave string will always need less compensation!!!



Author:  peterm [ Sun Jul 08, 2007 6:21 am ]
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Andy,
I looked at the Ryan 12 string guitar and he does intonate every string....
I believe that would be a must on a 12 string.
Author:  CarltonM [ Sun Jul 08, 2007 7:07 am ]
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Andy,

When you're gluing the bridge, where on the saddle do you place the set-back (compensation) point? Does it differ from your six-strings?
Author:  Andy Zimmerman [ Sun Jul 08, 2007 7:22 am ]
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I have my saddle slots pre drilled. I place my bridge so the center of the saddle width is the scale length plus 0.15 inches on the 25.4 scale length.
For my 24.9 scale I use 0.125

I have one of those fret rulers and I have etched this distance on the ruler just past the 12th fret. I place the "nut" line on the 12 fret and then the 12 fret mark on the ruler would be if I used no compensation. I just line up my bridge so the center of the saddle slot is on my compensation mark.
This may be confusing.
Bottomline 2x scale length plus 0.15 to center of slot
No difference in 12 string other than the scale length is a bit longer so I use 0.15 instead of 0.125
Author:  CarltonM [ Sun Jul 08, 2007 7:33 am ]
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Clearly explained. Thanks, Andy! I like your compensation mark on the ruler idea, too. Glad you threw that in!
Author:  Billy T [ Sun Jul 08, 2007 7:37 am ]
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[quote]Personally I think you need to intonate each individual string. Doing them in pairs is just not acceptable to me. [quote]

    You and me both! Every 12 I've played was a pain to tune. If one thinks about it, a 12 is even in more need of precise intonation than a 6.

    A lot more work!
Author:  KiwiCraig [ Sun Jul 08, 2007 11:41 am ]
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Good work Andy. Thanks for the thread and pics
Author:  Barry Daniels [ Mon Jul 09, 2007 3:13 am ]
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Andy, I found that notches on the saddle tend to result in a loss of power/volume. So I make the top of the saddle smooth, even when fully compensated. Obviously, your milage may vary.
Author:  Alan Carruth [ Mon Jul 09, 2007 6:03 am ]
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I use a wide saddle and the wire-on-top method to find the proper intnation points for each string as well. I take the saddle out, and mark three lines part way across: an angled line that connects the E and B string points, a line near the front of the saddle that connects the octave string points from low E to G, and another, further back, that connects the 'normal' strings from low E to G. Usually those two low-string lines are pretty close to straight, and the octave G is a little forward of the high E, since it's so tight.

I use a three-square (triangle) file to make a channel between the front and back lines on the low end. Then I file off the bone in front of and behind the lines all the way across, so that the strings can ride on the proper points. I notch out whichever ridge is not needed using a small round diamond jewelers file. That is, for the low E, the front ridge gets a half-round notch where the main string goes over it, and the back ridge a notch where the octave string would hit. Each string only hits it's 'proper' ridge. Then I polish everything up, and put it back.

This does the job and looks neat to me.
Author:  KiwiCraig [ Mon Jul 09, 2007 9:49 am ]
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Thanks Alan. I was trying to describe your method to Andy . Could we see a pic of one of your saddles ?

Author:  Andy Zimmerman [ Mon Jul 09, 2007 9:57 am ]
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Thanks Alan
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