Structural Integrity Audit
Body resonance is mapped via tap-tone at six points, with thresholds defined per model line to detect internal damage or previous repairs.
We use a calibrated tapping hammer and laser vibrometer to excite and measure body response at six fixed points: upper and lower bouts centerline, upper and lower waist, and both lower corners near the strap button. Baseline resonance frequencies and decay curves are compared to our in-house library of verified originals. Deviation beyond model-specific thresholds flags structural compromise or internal glue failure.
For instance, a 1959 Les Paul Standard exhibits a fundamental body resonance of 182 ±3 Hz at the upper bout center with decay time >1.2 seconds—our library shows <1.0 s correlates with neck-sets or cracks. We record the Q-factor (damping) and harmonic weighting. A single outlier point may indicate localized damage; systemic shifts suggest age-related dryness or board grain anomalies.
All tap-tone data is timestamped and stored alongside environmental logs (temp/humidity at time of test). We never grade a guitar structurally sound if any point deviates >10% from the model mean unless verified damage repair is documented. This allows us to distinguish between intentional design variance and failure, critical for era-specific tonal claims.
