Duplex, A Grotrian

[Richard Brekne]

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 these section the backscale started at 45mm  in the lowest notes of each
section, and tailed off to around 44mm and plucking each and every notes backscale
strings revealed that in each the pitch of the left most string was roughly a B8,
the middle a C8 and the right a C#8. The pitches of course rose very slightly as
the back lengths got just a bit shorter in the top of the section. But all notes
were basically the same.

The lower of the two capo sections had this same configuration but the frequencies
here corresponded to F7 F#7 and G7

C8 had a speaking length of 50 mm, and G6 about 125 mm.

Also interesting was the presence of what I can only call a bass front duplex
length. The strings left the aggraffes and traveled unmuted around 50 mm before
going over a half round. In the lowest bass this was a bit shorter... 45 mm. The
back scale started in the lowest notes at about 120 and increased to about 125.

The piano had no strip muteing anywhere at all exept the tenor sections 2nd front
lenght. There again the strings left the front termination and traveled 30 mm
before going over a halfround, then this time 120 mm over a felt rest to another
halfround before going on to the tuning pins. But this was the only section of
strings muted in any ways..

so .... any comments ??

--
Richard Brekne
RPT, N.P.T.F.
Bergen, Norway
mailto:rbrekne@broadpark.no