reproducibility... or copy... of early build

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reproducibility... or copy... of early build

Post by JurgenV » Tue Feb 05, 2019 7:41 am

I need some advice:
When I started building guitars, a few years ago, I somehow managed to build a really nice sounding guitar. Spruce top, maple back and sides, walnut binding. At that time I didn´t write down any dimensions, I just used the OOO plans from stewmac and added a scoop cutaway. Everything else I did by .... hmm let´s say "gut feeling". Including the scalloped bracing.
I had been really surprised about the outcome. Everyone else as well. Ok, I won´t say that guitar is the best sounding guitar ever but it´s quite nice. Bass but not too much, treble the same. Altogether it has a ... lets´s say warm voice. Doesn´t look much but sounds nice. (hmm, a lot of "nice") Ok let´s say it that way: my guitar teacher said that is a guitar he would exchange his good one for. And he has been a musician for more than 40 years.

Since then I tried to build a guitar with similar properties. I´m now a lot better concerning working with wood, have a lot more tools and the guitars I build are not bad (perhaps not as good as the ones build by a professional) and the small details look a lot better...
but I can´t get this sound again. Which after this long introduction leads now my question:
Is it possible to use the methods of the BOOK to somehow find hints on what to do to get in this direction?
Frequency spectrum, measurement of specific mobility ... anything?

Any comment to this topic would be appreciated.

if anyone is interested I can post pictures and the frequency spectrum as soon as I have some time

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Trevor Gore
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Re: reproducibility... or copy... of early build

Post by Trevor Gore » Tue Feb 05, 2019 12:25 pm

The book discusses in detail how guitars make sound. Guitars radiate sound from their vibrating parts, mainly the top. If a guitar top vibrates in a different way, it produces a different sound. The different ways a guitar top vibrates are called modes, and there aren’t that many of them. If the modes are tuned to resonate at particular frequencies with particular amplitudes, we can shape the way a guitar sounds. This is the essence of modal tuning and is what the Design section of the books is about. So if you can measure the performance of a guitar (its frequency response curve, which relates to the guitar's modes of vibration, its woodwork and its monopole mobility etc.) which is explained in the books, another guitar can be made with similar performance by copying those modes of vibration; especially their frequency and amplitude. All explained in the books.

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