Thursday, December 12, 2019

Cutting a Sound Port on a Guitar

In a previous post I mentioned that I was going to cut a sound port in the upper bout of the cedar/wenge guitar. Drilling/cutting sound ports in guitars has been popular for about the last fifteen years, it was original done with the claim that it made the guitar louder, but research has shown that it really doesn't make the guitar louder. It does give more immediate feed back of the guitar's sound to the player.
I found oval templates after a search on the Internet and settled on this size. A little spray adhesive helped attach the template to the guitar's upper bout...
I bravely went at the wood with a drill bit in my cordless drill...
and there is the roughed-in oval. Some exterior tear/blow out had to be dealt with.
After filing and sanding away the excess that didn't look like an oval, an oval appear. This hole immediately raised the tap tone of the top by one whole tone, from about F sharp-G to A flat-A, and it also reduced the side's stiffness, I can feel the entire guitar vibrate more, especially in the guitar's neck.
I started the French polish process by painting on coats of 3lb cut shellac with resin, I want to try an old technique of pore filling. Paint on shellac, sand down to wood leaving shellac in the pores and then do that as many times as needed until the pores are filled with shellac. Wenge pores are quite large, I don't feel like trying to push a large amount of 4F pumice into them.

Will this sound port make a better sounding guitar? I won't know until I put strings on it.

Thursday, December 5, 2019

What's On My Workbench: Cedar/Wenge Classical Guitar

I decided to experiment with a top bracing that is in the manner of Hermann Hauser and Daniel Friedrich. Hermann Hauser was a luthier from Germany, who made a guitar that the great Andres Segovia performed and recorded on for many years; Daniel Friedrich, a luthier in Paris, now retired, is well known for his innovative bracing derived from the work of luthier, Robert Bouchet.

The main reason why I am trying this experiment is that really loud classical guitars are in great demand these days by guitarists who compete in guitar competitions and young guitarists studying at music conservatories. I find it very interesting that most of these guitarists and professional performing guitarists mic and amplify their instruments in every concert setting. Why does one need a loud guitar if you are going to plug in? Why not have a beautiful sounding guitar that will touch the hearts of listeners? 

Now, to the guitar.

I used western red cedar from British Columbia for the top and wenge for the sides and back. I re-sawed the wenge with a table saw and finished it by hand with my Disston No.7 ripsaw, wenge is as hard as bubinga to cut! One thing about working with wenge, I was always getting slivers! I am surprised I didn't get slivers in my eyes! Bending wenge by hand on a hot bending iron is not for the faint of heart, it wants to fight! I had very little spring back with it, a nice benefit.

I know that for me, five struts without the angled cut off bars make great sounding guitar with volume and a gorgeous voice.

Adding the middle brace, which is directly under the bone saddle of the bridge, adds more sustain to the guitar's sound. The outer two braces provide extra rigidity to the top so I can bring the top's thickness down to 2mm or less, something around 1.7mm-1.9mm, which helps to increase the loudness of the guitar.

The five main braces are inlet into the lower transverse brace, and the opposite ends of the braces are anchored by kerfing blocks and the end block. I have done that on other guitars and they are loud! The cross braces go over the main struts, in the manner of Bouchet, and then I carefully plane away the brace wood to produce the sound I want.

Also popular today, are sound ports. These are additional sound holes drilled or cut into the guitar sides. Most are located on the bass side upper bout, this puts the port directly under the player's jaw, the feedback of the guitar's sound is more immediate available to the player. I will cut a sound port, where the maple veneer backing is located, once I get the guitar ready for French polish.

The black ring, made of wood veneer, at the sound hole is a short tornavoz, "tuned voice". The great Antonio de Torres used a large brass tornavoz on several of his guitars, the tornavoz decreases the Helmholtz effect of the guitar's sound chamber and from what I have read, the tornavoz helps increase the projection of sound. By adding a sound port, I will, from the research I have done, change "the pitch" of the guitar, the tornavoz is supposed to help offset this "change of pitch". If you want more information on sound ports and the tornavoz, go to the delcamp guitar forum and search for those items.

Honduras mahogany back braces on wenge.

The main binding trim is cut from a board of waterfall bubinga.

This is where I am at right now with the cedar/wenge guitar, glueing on the bridge with a vacuum press. I really like using this press!

Tomorrow, the plan is to temporarily install tuning machines, put a dummy fret at the first and twelfth fret positions and attach the bass and treble "E" strings. This allows me to adjust the geometry of fretboard so it will work best with the height of the bridge. Once I like the string action, then I will install the frets!

1912 Ex-Segovia Cedar/East Indian Rosewood Classical Guitar

Inspired by AndrĂ©s Segovia’s famous 1912 Manuel Ramirez guitar, I chose Western red cedar top and East Indian rosewood back and sides from m...