I played two mf notes on each horn; a 2nd line G and an octave higher, top of the staff, G. I recorded them directly to my hard drive with a 48 kHz sampling rate using a Shure BG4 mic and one channel of an Electrovoice mixer as a pre-amp. The equalization was flat and no reverb was used. I then made fast Fourier transform spectra with Sound Technologies' SpectraPlus system.
On the lower note (F4 concert, ~350 Hz) the Bach had considerably more
amplitude than the Schilke in the 2nd and 4th harmonics and also more
amplitude in the 2nd through 5th harmonics than it did in its own
fundamental (1st harmonic). The Schilke exhibits a considerably flatter
set of harmonic peaks all the way from the fundamental up to the 6th.
I used my High School Mt. Vernon Bach, M, model 37 trumpet (a rare bird) and a tuning bell conversion of a Shilke B6 trumpet, which has an M bore, fitted with a Large bell, which makes it equivalent to a B7L. I played them both with a Stork 1.5C mouthpiece with a #22 throat and an "S" backbore. I pushed the Schilke's tuning bell in all the way and pulled out the tuning slides on both trumpets ~1/2".
Somewhat to my surprise, there are differences in the spectra.
Figure 2. Schilke B6L with large bell, 2nd line G, mf
On the higher note (F5 concert at ~700 Hz) the Bach has more amplitude in the 2nd harmonic, but beyond that they are pretty similar.
Figure 4. Schilke B6L with Large bell, top of staff G, mf
I have seen this effect before, when what I consider to be the "darker" sound (Bach in this case) actually has a richer spectrum with more high frequencies. I have always assumed that "brighter" was equivalent to more high frequency components; whereas, it seems that the opposite is true.John T. Lynch
© Copyright 2001, John T. Lynch; Ralph J. Jones
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