• Developed with Robbie O'Brien of O'Brien Guitars
• Based on the pioneering research of Trevor Gore

Build Better Guitars Through Objective Measurement

You build two guitars with nearly identical materials, plans, and techniques—yet one comes alive with remarkable responsiveness while the other is simply... good. One of the biggest reasons is monopole mobility: how efficiently the soundboard converts string energy into sound.

The Cariko Monopole Mobility Measurement Tool was designed and manufactured by Cariko in collaboration with Robbie O'Brien for the O'Brien Guitars Lutherie Academy. It gives builders a precise, repeatable way to measure top deflection—a key indicator of soundboard stiffness during voicing—so you can replace guesswork with measurable data.

What Is Monopole Mobility?

Nearly all of an acoustic guitar's volume, projection, and tone come from the soundboard. Its primary vibration is the monopole mode, and monopole mobility describes how easily the top moves when energy is applied. A well-voiced top delivers better responsiveness, projection, sustain, dynamic range, and balance. The goal isn't simply a lighter top—it's the right balance of stiffness and mass for each instrument.

Why Measure Top Deflection?

Tap tones, feel, and experience remain invaluable. Objective measurement complements them. By applying a known load and measuring the deflection, you learn the stiffness of the complete top-and-brace system—before bracing, after bracing, during brace carving, and before closing the body. Recorded over many builds, these numbers let you repeat your best results.

What's Included

• Guitar Top Deflection Measurement Jig – a stable, repeatable platform for measuring top deflection.
• Digital Indicator – high-precision measurement of deflection.
• 1 kg Calibration Weight with protective storage case – applies a consistent test load.
• Online Calculator – works on any computer, tablet, or phone. Enter top deflection, top resonance frequency, and effective mass to get your monopole mobility value instantly.
• Microsoft Excel Calculator – calculate monopole mobility, save measurements for every instrument, and compare builds over time.

Both calculators are included at no additional cost.

💡 Pro Tip: Save the measurements from every guitar you build. Over time you'll have your own "recipe book" of successful tops.

Acknowledgment

The principles this tool supports are based on the research of Trevor Gore, co-author of Contemporary Acoustic Guitar Design and Build, which gave builders a scientific framework for voicing instruments through objective measurement. Learn more about the books on Trevor Gore's official website.

Measure with Confidence. Voice with Purpose. Build Exceptional Guitars.