Thanks for sharing Brad, I just received the “Mastering the Sound of the Acoustic Guitar” which is very useful. How do these compare. Is there as much practical application for the builder.
Hey Nathaniel, nice to hear from you. I think that these books compliment Mastering the Sound nicely. Calder
smith offers some historical perspective on his thoughts a couple of decades ago. French is very up to date, exploring and comparing many different builds and concepts. He has a section on sound hole size vs. body volume, which dovetails nicely with some of my latest discoveries. I have found that the sound hole/ side port shape and placement make a big difference in the body resonance frequency. The pictures below show two sets of similar ukulele. Two are similar tenor archtop ukulele and two concert flattop ukulele. The body resonance of archtop with the conventional oval hole and side sound port is A3 -10 cents. The other archtop with the combination of two sound hole/ side ports on either side of the neck has a body resonance of F3 -08 cents. The conventional flattop phase a body resonance of A3 -18 cents and the ipu shape has a resonance of F sharp 3 -20 cents. The sound pressure levels of the ukulele are similar, but not surprisingly the timbre of the two with the new sound hole design is darker.
Thats interesting, Do you know why the new design raises the body resonance from A3 to F3? Placement of the sound holes is not dissimilar from a slack key guitar design.
I think books like this are incredibly useful. Ukulele repertorie is quickly expanding with players wanting different sounds ands and colors from their instruments. I agree the traditional sounds should not be mimicking a guitar however its nice to have knowledge to draw from that allow use to make them sound anyway we want.
Aloha Nathaniel, your instincts are correct in this case, there is clearly more going on. The main impetus for my experimenting with this stems from an article I recently read on research on violin f holes. To paraphrase their conclusion, they stated that the majority of air movement occurs next to the edge of the sound hole. Thus sound hole with elongated shapes are more efficient enabling the instrument body in acting as an air pump. To put this to the test, I combined the sound holes and side ports and elongated the shape to resemble a football. An interesting byproduct of this is the calculation of the practical area of these sound holes is now an interesting mathematical exercise. I know from experience that there are three ways to adjust the body resonance of an instrument. You can thin the top/ back, which will lower the frequency. Or you can enlarge the sound hole (Helmholtz), which will raise the frequency. Clearly by changing the shape and position of the sound holes, I have altered how the top vibrates. My intention was to enlarge the top area of the monopole mode, thus lowering the frequency. I am used to seeing tweaks like these resulting in frequency changes of 10-20 cents not multiples of semitones. Just starting down this rabbit hole, more to follow.
