Continuing the work on the top.. It's taking an age because there's very little information about doing this - flattops yes, violins yes, bespoke archtop guitars - nope.
So to make the top resonate at a frequency, its frequency is proportional to stiffness divided by mass. This means you're using the shape of the dome arch, the thickness of top to define this.. in reality the grain direction, the length of grain (you're cutting through it to make an arch) etc all vary this.. plus you need a certain strength to hold part of the down force of the bridge from the strings (there's bracing too but that only takes some).
So to improve the quality of the resonance, we use Chladni patterns to discover what/where things vibrate (the gaps) and and what doesn't (the line). So you now see the sound vibrations on the top. Classically there's a number of different "modes" which are common - such as the whole top vibrating, part vibrating in opposition to others etc. You then make adjustments to the thickness (we're talking 0.1mm or less) to make the lines cleaner and sharper.
This one at 197Hz I'm calling this one 'the nun's legs up':
I won't bore you with the others - at 58Hz I have my classical pattern "mode 1".. which due to my guitar tail, doesn't look like a '+' cross but instead looks like "Y" thong, or better still an Angus cow with horns.
So to make the top resonate at a frequency, its frequency is proportional to stiffness divided by mass. This means you're using the shape of the dome arch, the thickness of top to define this.. in reality the grain direction, the length of grain (you're cutting through it to make an arch) etc all vary this.. plus you need a certain strength to hold part of the down force of the bridge from the strings (there's bracing too but that only takes some).
So to improve the quality of the resonance, we use Chladni patterns to discover what/where things vibrate (the gaps) and and what doesn't (the line). So you now see the sound vibrations on the top. Classically there's a number of different "modes" which are common - such as the whole top vibrating, part vibrating in opposition to others etc. You then make adjustments to the thickness (we're talking 0.1mm or less) to make the lines cleaner and sharper.
This one at 197Hz I'm calling this one 'the nun's legs up':
I won't bore you with the others - at 58Hz I have my classical pattern "mode 1".. which due to my guitar tail, doesn't look like a '+' cross but instead looks like "Y" thong, or better still an Angus cow with horns.
Last edited:
