an alien landscape

There are things I understand empirically that I don’t yet know how to comprehend on a spiritual level. I have found that, generally speaking, the opposite is also sometimes true.

It is perhaps paradoxical to say this, but when it comes to shaping and carving the braces for the back and soundboard of a guitar, both of these things were true at the same time. I had read plenty of advice on the topic, scoured over countless historical and current models and felt like I “understood” the basic ideas behind brace shaping, but when I was standing there with a sharpened chisel in my hand I was in awe of the task in front of me.

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This wasn’t quite like The Doctor staring across the dunes of Skaro, but I felt very much as if I were surveying an alien landscape. Not a hostile world, but one that was quite foreign to me. Where to begin carving? How much is too much? How much is not enough? What effect would each shaving make on the overall tonal characteristic of the guitar? Was I overthinking this?

I took a deep breath, closed my eyes, realized that you shouldn’t wield a sharp chisel with your eyes closed, opened my eyes back up and took a first stab at it.

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There that wasn’t so bad. I thought to myself.

I took another shaving, and another. Chips began to fly.

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The basic layout of what you see here is a wide but low (to the soundboard) “popsicle stick” closest to the neck to add structural integrity to the portion of the top under the end of the fingerboard. Just below that is a narrow but deep transverse brace which prevents soundboard twist and distortion when tension is added.

Above, and to either side of the X brace are two finger braces that reinforce the sound hole. I’ve seen people use a “donut” here. I don’t care for that. Then the x-brace which is nearly as deep (from the soundboard) as the transverse brace, but narrower to provide strength without dampening the top too much. Some people scallop these heavily. I did not. The X brace arms extend all the way to the sides of the guitar and are notched into the kerfing.
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Then there’s the bridge patch in the center and the lower face braces below the X brace. These add strength to an otherwise unsupported area of the top plate and run tangentially to the grain of the top plate reinforcing the center joint. The other smaller braces off to the sides of the X brace do roughly the same thing. The braces themselves are oriented so that the grain is always perpendicular or tangential to the grain of the soundboard.

All of these concerns about structural integrity finally need to balance out with the desire to have a top that is as light, flexible and resonant as possible.

With that in mind I began roughly shaping the upper and lower face braces before gluing on the X brace so some of the work was done, but now I needed to feather those braces out into nothing, and bring all of the braces into harmony with one another, all while listening for a mysterious “tap tone” that would let me know my work was done.
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And this is where the mystical art of guitar bracing crosses over from an empirical pursuit to an act of faith. You can “know” how much wood to remove, and you can approximate a model, but you have to learn to listen to the wood to understand when it is telling you to stop.

And it will tell you to stop. If you don’t listen, it will also tell you that you have gone too far.

This is the part when your non-luthier friends and family will look at you as if you’ve lost your mind. Tapping, listening, tapping, listening, trying to hear when all of the harmonics present in the wood come into alignment with each other and none of them overpower the others.

I’m sure that this is a skill that I will develop more fully with subsequent builds but I was amazed at exactly how listening closely taught me pretty quickly just what I was listening for. This is not unlike other areas of woodworking where you are obliged to “read” the grain in order to work the wood properly.

Rule #1 of woodworking: The wood has been around much longer than you. Listen to it. It has something to teach you.

After the basic shaping was done, I went back in and chamfered the edges of the braces and sanded them lightly. Some believe that shaping the peaks of the scallops and cutaways into pyramids has a significant effect on eliminating unwanted “wolf tones” Others believe that all sharp edges need to be eliminated to accomplish a balanced tone. Others argue for tonal nuances that I cannot even begin to comprehend.

I think some of that has merit. I think the rest of it is a leap of faith. In the end I followed my gut shaping the braces into something that felt good to me, looked pleasing to the eye and produced a nice balanced tap tone.

And then I signed it and called it a day.
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6 thoughts on “an alien landscape

  1. great progress! I have learned lately to just get started and see what you need to do next. I hope to build an instrument some day soon.
    Tell us about your signiture, google translate came up with…
    I have been living in the woods, I was stiff killed, according silence while I lived, died aged sweet

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  2. Jim,

    As always a great post, and one which really captures the intricacies of soundboard bracing (which, incidentally is my favourite stage of every guitar build). The first time you brace a guitar is a leap in the dark, but each soundboard that follows adds another small candle’s worth of illumination and experience from which to learn. It’s all very exciting.

    And as you’ve discovered, there is almost as much mumbo jumbo and pseudo science around bracing as there is round high-end hi-fi systems. The trick is to trust your ears, and learn from each build (that’s what I’m still doing).

    Those braces look nice and crisp, and I like the scalloping on the two tone braces. It’s going to be exciting to see how this one sounds. Good work!

    K

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    1. Thanks for the encouragement Kieran. As hesitant as I was to begin the first time, I can hardly wait to brace the next one!

      The scallops on the lower tone bars are definitely a nod to the hybrid X bracing in my current OM. It just seems to me that that is a really lively part of the soundboard and I wanted to preserve that as much as possible.

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      1. Agreed. I’ll be writing a full blog post on this soon, but in a nutshell the area below the bridge is all about resonance (ie tone). The area from the centre of the X up to the neck block is all about structure. So you can play with your bracing to control resonance and provide structural stability accordingly. That is a crude précis but gives you a decent starting point. I scalloped the tone bars on my 12 string which really warmed up the sound (got to stop 12 strings sounding too bright and harsh).

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