Scalloping the lower bout transverse brace

[JamesO]

Hi everyone,

I'm building with a 12' back radius. This is 3.6m rather than the 3m back radius in the books. Should I still leave the central flat area 13mm high as in Build 11.1.1.5? How wide do you typically make that flat spot? It looks to be around 75mm wide in the pictures?

Thank you!

[Trevor Gore]

If you have the 2nd Edition, see Build, p. 12.11, esp. the last paragraph.

[JamesO]

I have the first edition. Do you mind filling me in?

[Trevor Gore]

If you don't know how far to go, don't scallop the back brace initially. Glue the back to the sides, take the assembly out of the mould and tap the back, which will give you the B(1,1) frequency. The B(1,1) sits a little higher in frequency than the T(1,1)3 on the fully assembled guitar. Scallop away at the back brace until you have the B(1,1) frequency that you want.

[JamesO]

Thanks, Trevor.

[AKEric]

Could you please clarify Trevor. I read your response and had to find that section in the book because I had been using something a little different for my guitars. That paragraph says "The B(1,1) resonance is generally slightly lower in frequency than the fully coupled T(1,1)3 resonance in the completed instrument...". Can I assume what you have in the book is most accurate? B(1,1) lower, not higher than T(1,1)3.

Thanks,

Eric

[Trevor Gore]

Good catch! Yes, the book is right.