7.8 Going Further: The Bass Brass Instruments of Berlioz
387
Fig. 7.66 EFP plots for the bass tuba shown in Fig. 7.57d. Valves operated for pitches F1 (open
circles), E 1 (open squares), D1 (open triangles), and C1 (open diamonds). Also shown are
harmonics of F1 (filled circles), E 1 (filled squares), D1 (filled triangles), and C1 (filled diamonds)
C.F. Zetsche Söhne, Berlin, probably 3rd quarter nineteenth century) is illustrated
in Fig. 7.57d. The bore profile of this instrument with no valves activated is shown
by the green curve in Fig. 7.58. This profile differs substantially from that of the
ophicleide: over the first 1000 mm it remains almost cylindrical, and it then has
a smooth and gradual flare towards the 270 mm diameter bell. The impedance
peak frequencies for this instrument with no valves depressed are close to a series
of harmonics with fundamental F1, as shown by the blue EFP plot in Fig. 7.66.
Intonation problems associated with the use of valves in combination (Campbell and
Greated 1987) were reduced by providing more than three valves. The additional
tubing inserted by most valves can be adjusted by a separate tuning slide. The fifth
valve, for example, can be tuned to reduce the pitch by a minor third, allowing the
third valve to be tuned to give an accurate downward step of a perfect fourth in
combination with the first valve. The EFP values in Fig. 7.66 were obtained from
a reference measurement in which all the tuning slides were fully pushed in; for
performance the slides would be pulled out to different extents to optimise the
intonation.
Residual problems in pitching notes in the lowest register are revealed by the
irregularity of the EFP plots for n = 1 and n = 2. The sharpening of the lowest
resonance already noted on the ophicleide is evident in the plot with no valves
depressed. As the proportion of cylindrical tubing in the bore profile is increased by
activating valves, the flattening effect observed on the trombone comes to dominate.
The EFP values for the fingering used for the note C1 are shown by the green plot
in Fig. 7.66: the n = 1 peak is almost 3 semitones flatter than this nominal pitch.
387
Fig. 7.66 EFP plots for the bass tuba shown in Fig. 7.57d. Valves operated for pitches F1 (open
circles), E 1 (open squares), D1 (open triangles), and C1 (open diamonds). Also shown are
harmonics of F1 (filled circles), E 1 (filled squares), D1 (filled triangles), and C1 (filled diamonds)
C.F. Zetsche Söhne, Berlin, probably 3rd quarter nineteenth century) is illustrated
in Fig. 7.57d. The bore profile of this instrument with no valves activated is shown
by the green curve in Fig. 7.58. This profile differs substantially from that of the
ophicleide: over the first 1000 mm it remains almost cylindrical, and it then has
a smooth and gradual flare towards the 270 mm diameter bell. The impedance
peak frequencies for this instrument with no valves depressed are close to a series
of harmonics with fundamental F1, as shown by the blue EFP plot in Fig. 7.66.
Intonation problems associated with the use of valves in combination (Campbell and
Greated 1987) were reduced by providing more than three valves. The additional
tubing inserted by most valves can be adjusted by a separate tuning slide. The fifth
valve, for example, can be tuned to reduce the pitch by a minor third, allowing the
third valve to be tuned to give an accurate downward step of a perfect fourth in
combination with the first valve. The EFP values in Fig. 7.66 were obtained from
a reference measurement in which all the tuning slides were fully pushed in; for
performance the slides would be pulled out to different extents to optimise the
intonation.
Residual problems in pitching notes in the lowest register are revealed by the
irregularity of the EFP plots for n = 1 and n = 2. The sharpening of the lowest
resonance already noted on the ophicleide is evident in the plot with no valves
depressed. As the proportion of cylindrical tubing in the bore profile is increased by
activating valves, the flattening effect observed on the trombone comes to dominate.
The EFP values for the fingering used for the note C1 are shown by the green plot
in Fig. 7.66: the n = 1 peak is almost 3 semitones flatter than this nominal pitch.