C.F. Martin & Co J-40

Essential Information About the J-40 Guitar

• Jumbo body: a large body for generous projection and remarkable presence in accompaniment.


• Solid Sitka spruce top: precise attack, beautiful dynamics, and excellent chord definition.


• Solid East Indian rosewood back and sides: deep lows, bright highs, and ample sustain.


• Careful craftsmanship: forward shifted scalloped X bracing and dovetail neck/body joint for a lively response.

A Jumbo Folk Designed for Power and Elegance

With its jumbo body and high-end finishes (polished lacquer, "style 45" rosette, "reduced hexagon" inlays), the J-40 fits the spirit of great folk guitars designed to fill the sonic space. Its construction emphasizes harmonic richness and projection while maintaining modern playability thanks to a "Low" profile neck and a satin finish on the back of the neck.

For Which Guitarist and Styles?

This guitar is aimed at intermediate to advanced musicians seeking an expressive acoustic capable of taking the lead role in strumming (folk, pop, country) as well as more nuanced playing (ballads, arrangements, vocal accompaniment). The jumbo format and medium gauge metal strings promote a clear attack and excellent rhythmic hold, ideal for pick playing.

Sound

The solid Sitka spruce top provides clarity, precision, and a wide dynamic range: it responds equally well to light attack and powerful playing. The solid East Indian rosewood (back and sides) enriches the spectrum with dense lows, sparkling highs, and naturally long sustain, highly appreciated for open chords and complex voicings. The standard forward shifted scalloped X bracing (sculpted) optimizes top vibration, giving more fullness and projection, while the ebony bridge and bone nuts contribute to clear articulation and controlled intonation.

Recommended Compatible Accessories

To stay true to the original spirit, a set of medium gauge phosphor bronze acoustic metal strings (type 13-56) is perfectly suited. A set of picks (from soft to stiff) will also allow exploration of the full dynamics offered by the jumbo body.

Technical specifications

Category	Steel String Shaped Body	Marker	Reduced hexagon
Format	Jumbo	Nbrs of frets	20
Left handed	No	Scale (mm)	645 mm
Cutaway	No	Tuning pegs	Closed, golden finish, with large buttons
Strings	Steel	Bridge	Ebony
Nbr of strings	6	Nut	Bone 42.9 mm (Head), offset bone radius 406 mm (Bridge)
Top	Sitka Spruce	Original Strings	Martin SP Lifespan Phosphor Bronze Medium (SP7200)
Bracing	X	Cover/case	Type 580 geib style
Nets	Boltaron	Neck Type	Glued
Neck	Selected wood	Electroacoustic	No
Neck format	Low	Color	Natural
Nut Width	42.9 mm	Finishing	Glossy
Fingerboard	Ebony	Hardware	Nickel

Body type	jumbo, neck/body joint at the 14th fret	Side joint inlay	black/white Boltaron
Back and sides	solid East Indian rosewood	Binding	Boltaron
Top bracing type	standard forward shifted scalloped X	Finish	polished lacquer
Top bracing thickness	solid Sitka spruce 7.94 mm / 0.31"	Back and sides finish	polished lacquer
Bridge type	Belly style	Additional specs	beveled and polished
String spacing at bridge	54 mm / 2.13"	Neck shape	Low
Pickguard	tortoise	Neck finish	satin lacquer
Rosette	style 45	Neck/body joint	glued, dovetail joint
Top purfling	black/white Boltaron	Scale length	645 mm / 25.39"
Back purfling	black/white Boltaron	Number of frets	20
Back purfling inlay	style 45	Fingerboard width at 12th fret	54 mm / 2.13"
Side purfling	black/white Boltaron	Inlays	Reduced hexagon
Side joint	white Boltaron	Heel cap	white Boltaron with black/white Boltaron inlay