This is somewhat of an accidental instrument. It's based on a
brilliant idea by RP Collier to use electrical grounding blocks --
which are readily available at hardware stores -- as bridges for
thumb pianos/kalimbas. Bob's instruments are extraordinary;
can see and here some of them here.
You can see the grounding block clearly
in this photo. It is held down with three bolts, making it easy to
attach to potential soundboards. The tines pass through the round holes
and are held in place by screws, again, making it quite easy to swap out
and tune the tines. It helps to use a spacer to raise
the bridge up from the surface of the soundboard, since otherwise the
tines can buzz against the surface (which is not, mind you, always a bad thing!)
While I've had great luck using Bob's grounding block idea with
random sound boards and tines, this example was pretty much a failure
at first. The soundboard was a box which once held Sachertorte from Vienna.
It has an extremely thin top, which distorts heavily with the initial
pluck, creating a transient "thwack" that steal energy, as it were,
from the sustained tone. I added two bits of moulding
sandwiching the top to give a wider base and more weight to the
bridge, but the sound was still short, and without a clear
However, as I was taking the thing apart I struck one of the long
dangling tines with the screwdriver, and got a beautiful bell-like
tone. A bit of experimentation revealed that very long tines, which would
be inaubibly low in pitch if plucked, made great gong and bell sounds
when tapped with something like chopsticks. We're hearing clusters
of overtones well above the fundemental pitch of the tines; I also
suspect that tapping the tines excites some unusual sideways twisting
modes, which are relatively high pitched.
The instrument as pictured, and as played on the example below,
has tines made from street cleaner brushes found on the street, and
the metal inserts from a discarded set of windshield wipers. There
are also two bamboo skewers. I made no attempt to tune the tines;
the fact that they seem fairly harmonious is, I suspect, a
combination of luck and cross-coupling between the tines.
The example recording has been looped and edited from two
improvised recordings, one with the microphone about a foot from
the instrument, and one with the microphone actually inside the box.
hammered kalimba mp3