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| Durn Thing Sounds Like a Bongo! http://www-.luthiersforum.com/forum/viewtopic.php?f=10102&t=3111 |
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| Author: | Michael McBroom [ Mon Sep 05, 2005 3:02 am ] |
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I build classicals, and I've noticed that the pitch of a top changes throughout the build process. Once the box has been glued up, I'm usually expecting the top to have a pitch somewhere between G and G# when I thump it. For this current build, I'm using a bracing pattern based on a Bernabe that I examined back in July. I should have taken better notes, I guess, but my recollection was that the fan braces actually butted up against the bottom tone bar. Seemed to be rather a stout way to go, but given that the Bernabe design uses only three fan braces with a couple of small outriggers alongside the center fan, I figured that butting up the fans against the tonebar might be a good way to go. Well, once I got the box buttoned up, I was suprised at the pitch of the tap tone. There are clearly two tones -- middle C and the Eb above it. This seems to be way to high pitched, I'm thinking. Last time I put together a guitar that had a high-pitched tap tone, it ended up being a very quiet instrument, and I had to go back in and take about 50% of the mass from the Bouchet-style cross brace I'd used along the bridge saddle line. This made a huge difference in its volume and resonance. So, I'm thinking that, before I proceed any further, I should probably get in there with a short chisel and scallop the fans at the tone bar so that they are free floating. What do you guys think? What would you do in this situation? Best, Michael |
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| Author: | rlabbe [ Mon Sep 05, 2005 3:18 am ] |
| Post subject: | |
Why not get a fretboard on it, glue a temporary bridge on it while it is still in the white, and see how it sounds? If it needs gross adjustments it'll be very obvious. |
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| Author: | jfrench [ Mon Sep 05, 2005 3:25 am ] |
| Post subject: | |
Michael, I'd finish building it before making any changes - for a couple of reasons. One being that you can hear it before and after, thus getting a good idea of how the modification affected the sound. Its difficult to predict the sound of an instrument, especially if you are experimenting with different bracing patterns. If you tap on a Torres it is generally a dead sounding instrument... Jose Romanillos likened it (if I recall correctly) to sounding like cardboard, yet they are incredible sounding instruments when the strings are plucked. I've found the same thing.... the more "dead" the box sounds when tapping on it, the better the guitar with sound when strung. Weird, isn't it? [with that said though, the frequency of my boxes are usually much lower] Anyway, nothing ventured nothing gained. Have confidence in how you worked the soundboard before closing the box, and if changes need to be made do them later. |
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