multiple unison strings

[Stephen Birkett]

On the subject of multiple unison strings I was very surprised to
learn that the Weinrich phenomenon is also observed in harpsichords
under certain conditions. I've appended a very interesting message
on this subject from John Sankey.

Stephen Birkett (Fortepianos)
Authentic Reproductions of 18th and 19th Century Pianos
Waterloo, Ontario, Canada
tel: 519-885-2228
fax: 519-763-4686

------------------FORWARDED MESSAGE----------------------
I'm not aware of any published data on the equivalent phenomena
for harpsichords, but made a few measurements myself in
preparation for building a real Italian (which were almost
impossible to find in the 60's) during the three years I spent
in Cambridge England being inspired by Thurston Dart, Fenton
House, and the Galpin Society.

Old harpsichords vary more than pianos in string coupling and
sustain, even if large clavichords & square pianos are
included as pianos. A large German harpsichord, with very long
strings, massive bridge, and neutral soundboard, will, I am
certain, behave exactly in the way that is described for
pianos, but I've never had access to one to measure. My
measurements were on Italian and early Flemish instruments -
the latter show the two-slope effect, but also tend to show an
initial rise while the strings settle down into synch of as
long as a tenth of a second with two strings plucked. With one
plucked, the rise can be as long as a second on single-manual
instruments since the dampers are raised on all strings all
the time. French players, who prided themselves on their clean
sound, used two manual instruments (one 8' on each) whenever
they could, and set the plectra to not pluck simultaneously,
to avoid this effect, which muddies the sound by
harpsichordists' standards. Original German instruments that
have a 16' nearly always have it on a separate bridge for the
same reason.

The sound of Italian instruments is still underestimated - by
tuning both strings tightly in unison, the sound pours out in
milliseconds and carries unbelievably. I will never forget an
original Italian octavina I played in Durham Cathedral - it's
the longest in northern Europe, with the crypt extending the
west end, and I assumed that no one would hear me over the
almost-bellowing northern-English male choir, some sixty
strong. Then my friend whom I brought along to check out the
sound warned me - he could hear every last note I was playing
at the far end of the crypt, where the choir was just a
murmur! Anyway, by detuning one string from it's partner until
they just fail to couple tightly, the tone of old Italians in
good condition becomes almost as legato as a Flemish - quite a
different sound. By the time the initial ictus has cleared,
most are in the shallow slope stage when tuned that way.

And, never forget the effect on sustain of 10,000+cu.ft.
solid-stone-walled rooms with only a few percent of the
surface covered by tapestries!

--
John Sankey              bf250@freenet.carleton.ca
Music is Beauty, Beauty is Truth, Truth is Freedom