Sonically Graded (4pc) Vault

4-piece tops are cut from a smaller section of a tree, representing less of any tree's life (say 120 years, instead of 300), and are therefore more consistent in all of their physical properties. It’s a 1-inch board that’s resawn into 4 pieces—basically, narrower panels from the same board. Typically, the two center pieces are bookmatched, with the outer pieces also cut from the same board—either slip-matched or double-bookmatched depending on the look and layout.

We offer 4-piece tops as a way to increase yield from smaller-diameter logs. For PRT, in one way, this is a sustainable approach that allows us to reduce waste and make full use of high-quality logs, especially those that wouldn’t otherwise meet size requirements for 2-piece sets.

Each 4-piece top is cut from a single board—typically resawn and joined as a bookmatched center with outer wings from the same board. Depending on the layout, it can be presented as a double bookmatch or a slip match. This product is currently used by large-scale manufacturers like Martin and Taylor Guitars, and, as in our 2-piece tops, allows for a consistent, high-performance top with excellent symmetry and sonic integrity. It also helps lower the cost of entry for sonically graded tops, making them more accessible to builders who want premium soundboards with full data without the premium price of a 2-piece top.

Yes. When properly joined and braced, a 4-piece top performs on par with a 2-piece top in both structural integrity and tonal response. Because the panels are cut from the same board and matched for grain and stiffness, the joins are seamless, visually and acoustically. Once thickness-sanded and braced, most luthiers find no perceptible difference in resonance, strength, or responsiveness.

We currently offer Sitka spruce and Lutz spruce, both tested using the BING sonic grading system. These species are favored for their stiffness-to-weight ratio, responsiveness, and tonal clarity. Each top is measured for density, stiffness, and damping (Q value) so you can select a top that aligns with your tonal goals.

Each board that makes up a 4-piece top is tested individually before joining. We measure density (kg/m³), stiffness (MOE), and damping (Q) using the BING system. 

BING is a non-destructive acoustic test that analyzes vibration response from a steel-ball impulse. Boards are then matched to ensure that all four pieces share similar acoustic properties, resulting in a balanced, predictable soundboard.

It depends on your playing style, tonal goals, and the size of the guitar you're building.

• Low density (350–400 kg/m³): Highly responsive and warm. Ideal for fingerstyle players or light-touch techniques. Best suited for smaller-body guitars where delicacy and nuance matter most.
• Medium density (400–435 kg/m³): Balanced across the tonal spectrum with good projection and warmth. A versatile option for mid-size guitars and mixed playing styles.
• High density (435–500 kg/m³): Offers strong projection, clarity, and dynamic range. Well-suited for jumbo or large-body guitars, or for players with a heavier attack who want more headroom and focus.

Each 4-piece top includes individual sonic data (density, stiffness, and Q value) to help you match the material to your guitar build.

Yes. Each 4-piece top is resawn from the same 1-inch board, ensuring natural continuity in grain, color, and texture. Because all four panels originate from the same piece of wood, visual matching is inherently strong. We take care to align the grain during bookmatching or slip-matching, so the joined top presents as a unified surface.

All Vault sets are dried, stabilized, and conditioned in our dehumidification kiln. Moisture content is kept at about 8.5% +/- for long-term stability and tonal reliability. That being said, we always recommend that you dry and acclimate the wood according to your own schedule/protocols.

Yes. Once assembled and finished, a 4-piece top delivers the same tonal response, strength, and projection as our 2-piece sonically graded tops. Every component is tested, matched, and graded to the same rigorous standards, ensuring that your instrument sounds and looks exceptional, no matter how the top is joined.