2016 Rosewood OM | tommillerguitars

Rosewood / Sitka OM Guitar #2

OM guitar with Sitka spruce top, curly koa binding and abalone purfling

Rosette with lacewood and double abalone rings

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.

OM guitar soundboard with traditional X bracing

OM guitar Chladni pattern, monopole at 172 Hz

OM guitar Chladni pattern, long dipole at 344 Hz

OM guitar Chladni pattern, cross dipole at 311 Hz

Frequency spectrum of Rosewood OM guitar

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.