agentsvr Posted January 13, 2005 Report Share Posted January 13, 2005 (edited) I have a friend that works very well on wood (he's professional). I gave him an idea to make a guitar and he did (it's a stell acustic guitar). The box, arm (and reinforcement), type of wood, etc seems very very good, but... Trying to tune his guitar i realise that he didn't got the distances right. (He says the guitar is tuned great, but i know it isn't, unless you play loose strings) I was wondering what is the mathematical formula for the 12 temperated tunes? I know i must have that somewhere but if you could help me with the distances it would be very much appreciated. Also, i know that to get ressonancy each builder puts inside the box various strips in each one personal style. Some open more holes in the box, etc.. I was wondering if someone could help me with those too... Also is there a "good" minimal height for the distance between the string and the arm (so it won't hit against the arm and make silly noise)? thank you, David Edited January 13, 2005 by agentsvr Quote Link to comment Share on other sites More sharing options...
guitar_ed Posted January 14, 2005 Report Share Posted January 14, 2005 Hi Agentsvr, I can help with one question, namely the distance question. It is actually quite simple. Measure from the nut to the 12th fret. It should be the same distance from the 12th fret to the bridge. I did not understand the rest of your post to reply to it. Guitar Ed Quote Link to comment Share on other sites More sharing options...
thedoctor Posted January 16, 2005 Report Share Posted January 16, 2005 Ed, if it helps I believe he is calling the neck the "arm". My best guess is he is also referring to bridging/bracing and sound-holes. Other than that, my dog ain't in this fight. Quote Link to comment Share on other sites More sharing options...
Jehle Posted January 21, 2005 Report Share Posted January 21, 2005 The fret spacing can be multiplied out using the 12th root of 2. Make an excel spreadsheet and populate it like this... it should take all of 5 minutes. nut to bridge = x (2) ^ (1/12) = e x x / e (nut to 1st fret) x/e /e (nut to 2nd fret) x/e/e / e (nut to 3rd fret) etc... until you reach 21, 22, 23, 24, or more frets. Go wild here. Quote Link to comment Share on other sites More sharing options...
agentsvr Posted January 22, 2005 Author Report Share Posted January 22, 2005 (edited) Thank you Jehle. That should be what i need :-) I'm sorry the mess up with the namings but in portuguese we use diferent names... you can forget about the other questions since it seems this forum is only about electrical instruments... Edited January 22, 2005 by agentsvr Quote Link to comment Share on other sites More sharing options...
Jehle Posted January 22, 2005 Report Share Posted January 22, 2005 You're welcome. Don't worry about getting the names wrong. Your English is much better than my Portuguese. We are mostly electric guitar oriented here. There are a few acoustic guru's, but not as many. Keep asking questions, learn where you can, and have fun. Quote Link to comment Share on other sites More sharing options...
Hoser Rob Posted January 29, 2005 Report Share Posted January 29, 2005 I assume by "play loose strings" you mean tuning the guitar down. If it plays in tune like that but not in standard tuning, the problem is not in with the placement of the frets, it's the placement of the bridge saddle. I think by strips inside the body you mean the braces. Those are there not so much for resonance but for structure. They need reinforcement because an acoustic guitar body is basically a wooden box made of 1/8" (3 mm) wood that you then apply 150 lb. or more of string tension to. Any luthier can tell you a lot of the challenge in making acoustics is making them so that they don't fall apart under all that tension, but still vibrate freely. And the braces aren't really done that much in an individual style. The patterns used are fairly standard. By height from the arm I assume you mean string height from the neck. It's usually measured from the top of the 12th fret - this is the half way point, so if you wanted to lower it by 1/64" you'd lower the bridge by 1/32". By "silly noise" I assume you mean buzzing strings. There's not really a standard for this I know of. How low you can get it depends on how straight you can get the neck, how flat the fingerboard (the tops of the frets have to be parallel), and whether you have any high or low frets. As a generalization, 1/16" at the 1st (treble e) string or less would be low action, 3/32" or more would be high action. The 6th string should usually be 1/32" higher than the 1st or your tone won't be balanced from string to string. Your playing style affects this a lot too. A fingerstyle player can use much lower action than someone who plays hard with a heavy pick. OK that's enough of a rant - sorry for the non-metric units - Canada is supposed to be metric but I find inches a lot more useful here. Quote Link to comment Share on other sites More sharing options...
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