Official Luthiers Forum! :: View topic - Tuning soundboard to a note ?

What Roger said.
I've had a look at the plan - if you followed the bracing dimensions fairly closely, scalloping etc., I wouldn't worry about this for a first build.
The main thing to watch out for is not to have the final frequencies of the back and top the same after the box is closed.
Try to have 1 to 3 semitones separation, with the back higher than the top, it is said to be desirable.
Frequencies can be played with a bit while the guitar is still "in the white"- box all together, and the top frequency predicted reasonably when the bridge is fitted.
The edges of the top can be thinned to drop the frequency, same with the back. Braces can to some extent be worked on.
Dropping the frequencies is a lot easier than increasing them.
I'm sure it will turn out pretty good as per plan, maybe a bit over-braced but so were many first builds, and I'm still playing mine. Not too bad and improved with time.
Just take notes of your impression of the woods, thicknesses, width and height of the braces etc., and you can change things as you feel fit next time. Oh, nearly forgot density of the woods can be very useful.
There will, of course, be a next time?

Author:	Cablepuller [ Tue May 19, 2015 12:44 pm ]
Post subject:	Tuning soundboard to a note ?
Hi Just wondering if theres a recommended note to tune the soundboard and back to Tapping my OM soundboard on the bridge plate gives a C note and the back gives a Bflat I haven't shaved the front braces much yet as not sure exactly what im doing really Someone told me it should be A for top and Aflat back I might be on a wild goose chase Any info please

Author:	Mike Collins [ Tue May 19, 2015 1:21 pm ]
Post subject:	Re: Tuning soundboard to a note ?
c & b# are the same note. This may cause some trouble Maybe Al Carruth can help ya. PM him. Mc

Author:	Cablepuller [ Tue May 19, 2015 1:25 pm ]
Post subject:	Re: Tuning soundboard to a note ?
Oops meant B flat on back

Author:	Colin North [ Tue May 19, 2015 1:41 pm ]
Post subject:	Re: Tuning soundboard to a note ?
Are top/back fitted to the sides yet?

Author:	Cablepuller [ Tue May 19, 2015 1:51 pm ]
Post subject:	Re: Tuning soundboard to a note ?
Colin North wrote: Are top/back fitted to the sides yet? No not yet Colin

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Author:	Rodger Knox [ Tue May 19, 2015 2:12 pm ]
Post subject:	Re: Tuning soundboard to a note ?
IIRC, the pitches of the free plates are not that important, but the difference between the top and back should be about 2 semitones. Mr. Carruth uses Chaldini patterns for free plate tuning, but the shape of the modes are more important than the frequencies.

Author:	Cablepuller [ Tue May 19, 2015 2:58 pm ]
Post subject:	Re: Tuning soundboard to a note ?
Rodger Knox wrote: IIRC, the pitches of the free plates are not that important, but the difference between the top and back should be about 2 semitones. Mr. Carruth uses Chaldini patterns for free plate tuning, but the shape of the modes are more important than the frequencies. Thanks rodger Sorry music theory is terrible Whats 2 semitones from c Cheers

Author:	Rodger Knox [ Tue May 19, 2015 3:48 pm ]
Post subject:	Re: Tuning soundboard to a note ?
Each fret is a semitone, Bflat is 2 semitones below C.

Author:	Bryan Bear [ Tue May 19, 2015 4:31 pm ]
Post subject:	Re: Tuning soundboard to a note ?
In addition to the pitch changing when the plate is glued to the rim, it will also behave differently when the bridge is glued on. Rodger, was your 2 semitone based on free plate or final strung up guitar? I have yet to get a handle on all of this. . .

Author:	Colin North [ Tue May 19, 2015 5:01 pm ]
Post subject:	Re: Tuning soundboard to a note ?
What Roger said. I've had a look at the plan - if you followed the bracing dimensions fairly closely, scalloping etc., I wouldn't worry about this for a first build. The main thing to watch out for is not to have the final frequencies of the back and top the same after the box is closed. Try to have 1 to 3 semitones separation, with the back higher than the top, it is said to be desirable. Frequencies can be played with a bit while the guitar is still "in the white"- box all together, and the top frequency predicted reasonably when the bridge is fitted. The edges of the top can be thinned to drop the frequency, same with the back. Braces can to some extent be worked on. Dropping the frequencies is a lot easier than increasing them. I'm sure it will turn out pretty good as per plan, maybe a bit over-braced but so were many first builds, and I'm still playing mine. Not too bad and improved with time. Just take notes of your impression of the woods, thicknesses, width and height of the braces etc., and you can change things as you feel fit next time. Oh, nearly forgot density of the woods can be very useful. There will, of course, be a next time?

Author:	Colin North [ Tue May 19, 2015 5:04 pm ]
Post subject:	Re: Tuning soundboard to a note ?
Cablepuller wrote: Rodger Knox wrote: IIRC, the pitches of the free plates are not that important, but the difference between the top and back should be about 2 semitones. Mr. Carruth uses Chaldini patterns for free plate tuning, but the shape of the modes are more important than the frequencies. Thanks rodger Sorry music theory is terrible Whats 2 semitones from c Cheers Down would be B flat, up would be (EDIT!) D

Author:	Alan Carruth [ Wed May 20, 2015 11:25 am ]
Post subject:	Re: Tuning soundboard to a note ?
Right: you can't predict the assembled pitches of the top and back very well from the 'free' plate pitches. It's usually a good idea to have the final pitches of the top (in particular) and the back a bit off from scale pitches. If the top comes in exactly at G~196 you could end up with a 'wolf' note at that pitch. Depending on how active the top is, and what else is going on, it might just add an interesting bit of variation, or it could give a 'thumpy' note that is loud with little sustain. A close match can also play hob with the intonation of notes near that pitch. Some folks advocate having the main resonances fall halfway between scale pitches, which helps avoid troubles. Generally speaking I find that gluing on the bridge drops the 'main top' pitch a bit; it adds more mass than stiffness. You can use that to help fine tune things.

Author:	Cablepuller [ Wed May 20, 2015 11:46 am ]
Post subject:	Re: Tuning soundboard to a note ?
Colin North wrote: What Roger said. I've had a look at the plan - if you followed the bracing dimensions fairly closely, scalloping etc., I wouldn't worry about this for a first build. The main thing to watch out for is not to have the final frequencies of the back and top the same after the box is closed. Try to have 1 to 3 semitones separation, with the back higher than the top, it is said to be desirable. Frequencies can be played with a bit while the guitar is still "in the white"- box all together, and the top frequency predicted reasonably when the bridge is fitted. The edges of the top can be thinned to drop the frequency, same with the back. Braces can to some extent be worked on. Dropping the frequencies is a lot easier than increasing them. I'm sure it will turn out pretty good as per plan, maybe a bit over-braced but so were many first builds, and I'm still playing mine. Not too bad and improved with time. Just take notes of your impression of the woods, thicknesses, width and height of the braces etc., and you can change things as you feel fit next time. Oh, nearly forgot density of the woods can be very useful. There will, of course, be a next time? Thanks Colin good advice

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