Custom Shop Build Overview

The Martin Custom Shop GJ-28 Sunburst Grand Jumbo is a bold and expansive acoustic guitar that brings the rich harmonic complexity of a Style 28 into a powerful Grand Jumbo platform.

This Custom Shop build pairs a premium spruce top with East Indian rosewood back and sides, delivering deep bass, shimmering overtones, and a wide dynamic range. The larger Grand Jumbo body increases internal air volume, producing enhanced projection, greater sustain, and a full, room-filling voice.

Finished in a striking vintage-inspired sunburst, this guitar blends traditional Martin tone with a visually rich aesthetic that stands out both on stage and in the studio.

Why the Grand Jumbo Body Matters

The Grand Jumbo body shape expands on the familiar dreadnought concept by increasing internal air volume and surface area, creating a more expansive tonal footprint.

Deep, piano-like bass response
Greater overall volume and projection
Wide dynamic range for expressive playing
Full, immersive sound ideal for live performance

Combined with rosewood back and sides, the result is a guitar that delivers powerful low end, complex overtones, and exceptional sustain.

Custom Shop Craftsmanship

Handcrafted in Nazareth, Pennsylvania, this Custom Shop instrument features Martin’s traditional dovetail neck joint and solid tonewood construction to maximize resonance and long-term stability.

The guitar is built to deliver both strength and responsiveness, allowing the top to move freely while maintaining structural integrity under dynamic playing styles.

The elegant sunburst finish complements the classic Style 28 aesthetic, adding vintage-inspired visual depth to this modern Custom Shop build.

Tone & Performance

The GJ-28 delivers a rich, complex voice with the depth and overtone content that players expect from a rosewood-bodied Martin. The Grand Jumbo body enhances both projection and sustain, creating a powerful and immersive tonal experience.