Duplex, A Grotrian

[Delwin D Fandrich]

----- Original Message -----
From: "Richard Brekne" <Richard.Brekne@grieg.uib.no>
To: <pianotech@ptg.org>
Sent: November 10, 2001 8:41 AM
Subject: Duplex, A Grotrian


> With all this talk I thought I would measure a few rough distances on a
piano with
> probably the most active duplex system I have ever run into. I have
mentioned this
> instrument before and it has what sort of reminds me of a rivited cymbal
quality to
> it
>
> So here are some numbers that I personally would love to have some
analysis on as
> too what you folks would expect to "hear" from this configuration.
>
> Throughout the entire top two sections the front duplex was a sort of
double
> dublex. From the capo bar the strings travel up 30 mm to a first half
round, then a
> further 50 mm to another before going on to the tuning pins. Neither of
these
> lengths are muted and both, when taped off, result in noticable difference
to the
> sound of the piano, mostly the length from the capo to the first halfround
tho.

In my article on Duplex Stringing I wrote that a string deflection angle of
15º to 20º should be considered minimum for adequate speaking cutoff. As the
article points out this is an interactive parameter with the length of the
duplex string segment. Longer duplex string segments require larger string
deflection angles and shorter duplex string segments can get by with
somewhat shallower string deflection angles. Nothing I have read or
encountered since then has caused me to alter this view.

I consider a 30 mm front duplex string segment to be getting on toward the
long side and a string deflection angle of approximately 12º is considerably
on the shallow side. It shouldn't be suprising there is some noise there.

Especially, though you don't mention it, if the V-bar is a bit more like a
U-bar. The parameters you give will accentuate any problem there might be
with the shape of the V-bar.

Del