Interest in improving the sound of my guitars led me to voicing guitars using free-plate tuning with Chladni patterns. Chladni free plate patterns were performed on the guitars that I built from 2003 through 2008, including guitars from the Beta guitar to the Walnut Phi. Free plate tuning is a tool that has a long tradition in voicing violins, and over the past decades has been used in voicing guitars. The source for much of my information and guidance was provided by Alan Carruth in luthier forums. I also attended a 2007 Healdsburg Festival workshop on free plate tuning by luthier Mark Blanchard.
One of the goals of free plate tuning is to tune the soundboard and bracing to form a closed circle on the ring-and-a-half mode. My first attempts at “closing the circle” were significantly unsuccessful as seen on my Beta guitar.
A change to a double X bracing system with a bridged lower X allowed me to tune braces to get the closed circle. In hindsight, I was overbuilding the guitars even though I was able to close the circle. Bracing was 5/16” wide, soundboards were nearly 3mm thick, and the back was about 2.5mm thick.