Hello MMD! Due to problems with our mail server I have not been able
to answer anything in the last few days (Mail bomb!!!).
The term "Glockenspiel" is used by German organ-builders for a
metallophone. Glockenspiel means literally "play of bells", although
bells were seldom used to make the sound.
A metallophone is the play that exists of metal bars (mostly steel, but
sometimes aluminium, brass or other metals are used). They will sound
best when hung at 2/9 of their length from both sides. If holes are
drilled in the bars they both should be drilled to prevent impurity of
sound, even if only one hole is used.
This goes for wooden bars too; these are referred to as "Xylophone",
which is derived from the Greek word "Xylos" for wood. European organ
builders were not always very correct in the use of these names;
sometimes a (steel) metallophone was referred to as Xylophone!
An interesting property of vibrating bars is their side-tone. The
pitch of this side-tone is depending on the relation between thickness
and width of the bars. If you make them twice as thick as they are
wide, they will give an octave as side-tone; with 1:3 you will get a
duodecime, etc. This does not seem to be generally known, but it is
important for the sound these bars make.
Hans van Oost, Netherlands
[ I think 'side-tone' is known in English as the overtone or partial.
[ The resonant chamber (pipe) of wind instruments produces overtones
[ which are integral multiples, or harmonics, of the fundamental
[ frequency. But mass-spring resonators, such as piano strings and
[ metallophones of all kinds, can resonate simultaneously at several
[ unrelated frequencies.
[ The man who tunes the bronze carillon bell (and who finds the best
[ place to strike it) attempts to adjust the strongest overtones for a
[ pleasant sound. Careful design of the glockenspiel or xylophone bar
[ can bring the strong overtones into harmony (zero beat) with the
[ fundamental frequency; that's quite important, as Hans says.
[ -- Robbie