Carbon fiber composite, an alternative to brass (?)Hannes W. Vereecke
Carbon fiber composite (CFC) is broadly accepted as a high-quality alternative for many applications in contemporary musical instrument making such as by the construction of guitars, flutes and violin bows. However, in brass wind instrument making, the application of CFC is not yet established. To some extent this is caused by aesthetic considerations and preconceptions concerning the acoustical effect. The proposed study was conducted to determine whether the use of CFC instead of brass would have an acoustical effect on the sound and playability of brass instruments. The acoustical characteristics and the playability of a modular brass wind instrument with interchangeable brass and CFC bells were analyzed with impedance and transfer function measuring gear. The vibrational behavior was studied with laser interferometry. Finally, playing tests have been conducted with members of the trumpet section of The Tonhalle Orchestra Zurich. First results of the vibrational analyses revealed large differences in a frequency range between 600 and 1.000 Hz. The transfer function of the CFC bell in that particular range was considerably higher than the transfer function of the brass bell. Differences in the impedance amplitude have been found, but they did not entail any considerable deviation in the frequency range. The CFC bell radiated more energy in a range between D5 and G#5 compared to the brass bell. These empirical findings have also been confirmed by subjective reports of professional performers. The playing-tests revealed that it was barley possible to distinguish the sound of the brass and carbon bell.