Rosewood / Sitka OM Guitar #2
Tonewood
This guitar is the second of a series of two OM guitars constructed with traditional Martin style bracing. The soundboard is Sitka spruce, back and sides are EI Rosewood, curly koa binding and back strip, abalone purfling, and a lacewood rosette with double abalone rings. It has a five piece neck with the center strip of mahogany. The fretboard and headplate are ebony, with abalone dots and diamond inlays in the fretboard. Dark Brazilian rosewood bridge with ebony bridge pins. The finish is my first effort with Royal-Lac shellac based finish.
Completed in 2016.
Voicing and Construction
The soundboard for this guitar is the most dense that I have used @ 560 kg/m^3. Vibrational stiffness was good, so initial thickness was 2.5mm tapering to 2.3mm at the perimeter to meet my target long grain frequency of the unbraced soundboard.
Bracing pattern of the top is based on the Martin X-brace; bracing pattern of the back is based on the pattern described in Trevor Gore’s books.
These images show the monopole, cross dipole and long dipole resonance patterns after completion, along with the coupled frequency spectrum. The voicing process for this guitar was easier than previous attempts. Resulting sound is as expected.
Resonances:
Top monopole 172 Hz
Cross dipole 311 Hz
Long dipole 344 Hz
Back 214 Hz
Air 91 Hz.