TPC system – Tonewood parameters characterization

I designed the Tonewood Parameters Characterization software specifically for luthiers. This innovative tool analyzes the audio impulses from a tap test to calculate key mechanical properties of the wood, including:

  • Q (quality) factor
  • Young’s modulus
  • Density
  • Radiation coefficient

The parameters are calculated with the method of the free beam, with the sample usually excited on its first longitudinal bending mode, along the grains of the wood.

The software allows to

  • Save the complete measurement files.
  • Export the data for postprocessing or easy access on the supplied excel sheet.
  • Record the tap tone of tone wood samples to constitute a virtual audio database of the wood stash.
  • Measure frequency response of complete instruments and evaluate damping factor of single resonances.

A dedicated support rig should be used to handle the sample and excite the resonance without interfering on its oscillations; the quality of the excitation stimulus and the support rig have a strong influence on the consistency and precision of the results.

System requirements

The software runs on Windows based 64 bits PC. The USB measurement microphone MiniDSP Umik-1 is suggested, available as main audio input of the system. A wireless mouse and keyboard system should be used, to keep the working space cable free and maximize the simplicity of the setup. A Laptop computer is also a good choice.

Where to perform the measurements?

TPC system should be installed in a quiet room, with smooth acoustic characteristics; the measurement must be performed in the close field (microphone at around 5cm from the plate), to avoid reflections from the wall to interfere with the acquisition.

TPC software interface

Signal processing

Once acquired the audio sample the three signal windows allow to postprocess it in both the time and frequency domain.

The main purpose of the software is to calculate the tone wood parameters and the Q factor.

Nevertheless, it is possible also to measure:

  • Frequency response of complete instruments:
  • Calculate the damping factor of specific resonances.
  • Visualize decay time of different spectrum portion of the instrument’s bandwidth.

The TPC software, thanks to its specific versatility, is a powerful tool to investigate both tone wood samples characteristics, and the sound produced by the instrument in its various manifestations.

The software package comprises:

  • TPC installer (windows only)
  • Excel data import spreadsheet
  • Tonewood audio sample, with TPCA file, jpeg export, txt export
  • Acoustic guitar measurement with audio sample and TPCA file.
  • 3D drawing of marble ramp
  • 2D drawing of suggested measurement Jig.

The price of the TPC software is 900 euros, comprising:

  • Tonewood parameters characterization software
  • xls import spreadsheet
  • marble ramp 3D drawing
  • measurement jig 2D drawings
  • audio and Tpca samples

EI Nicoletti Giuliano – No. SIRET: 920 500 170 00013 – Sorbiers, France