In my slowly proceeding street organ project I finally filled some
empty spaces with a 20-note percussive harp, a project that of course
took much more work than originally planned, all spare time this year.

For your discouragement or enlightenment I have written a technical
article about this designer's delight, perhaps over-ambitious, which
Robbie has placed in the MMD Tech site at
http://mmd.foxtail.com/Tech/chimes.html

The harp sounding bodies are tuning forks made from square aluminum
tubes, played with electropneumatic pressure actuated hammer actions
that include escapement, backcheck and damper mechanisms.  A number of
theoretical issues are covered with simple formulas, and the design is
presented with drawings, photos, measurements, and sound samples.

In reviewing this article Richard Vance suggested that the resonator
Q value is worthy of some clarification.  As this useful concept falls
somewhat beside the harp it finalized into a separate article at
http://mmd.foxtail.com/Tech/qval.html .  This contains some basics,
illustrative examples, rules of thumb, and a side look to what is
a decibel.

Johan Liljencrants
Stockholm, Sweden