[pianotech] S&S K(52) Restoration

[Gene Nelson]

I appreciate the detailed explanation.

I am not seeing rib support for the bass bridge?? That is, not the kind of
support that I would typically design into a grand rib pattern.

Gene

 

 

  _____  

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Delwin D Fandrich
Sent: Friday, May 18, 2012 10:46 AM
To: pianotech at ptg.org
Subject: Re: [pianotech] S&S K(52) Restoration

 

Yes. The Z-Bar extends from just below the end of the treble bridge—where it
is physically attached to the back structure—to a point just opposite the
tenor end of the bass bridge. From just under the tenor bridge the Z-Bar is
glued to the soundboard panel but not the back structure. The ribs are
centered on the bridge and extend up to the Z-Bar. There are no functional
ribs below and to the right of the Z-Bar although we did end up putting
several thin, acoustically non-functional ribs over there to keep the solid
wood soundboard panel from buckling and cracking. 

Description: C:\Documents and Settings\Delwin D Fandrich\My
Documents\FileCabinet -- DDF\Piano Designs\Fandrich--122 Vertical\U22-Master
Drawings\U22 - Iron Plate Master jpg.JPG

 

The Z-Bar is essentially a soundboard sizing and shaping device and an
impedance control device. It keeps the soundboard area small in the treble
area where the frequencies are high and the system mobility needs to be
restricted, allowing it to become gradually larger further down where the
frequencies are lower and the soundboard needs more surface area and more
mobility. Think of it as a mechanical crossover network.

 

The lower portion of the soundboard “floats” free of the back structure
giving the low end of the bass bridge the controlled mobility needed to
develop sound energy in the fundamental and lower harmonics.

 

In several demonstrations before groups of piano tuners and technicians the
audience members were unable to say precisely where the bass/tenor
transition took place. In one demonstration before a group comprised mostly
of piano teachers and piano tuners and technicians the piano was compared
note by note starting at C-88 and working down with a Bösendorfer Imperial
grand; the consensus of the audience was that the little 122 cm tall
vertical produced more power, along with better clarity and dynamic range
down to about the last two octaves in the bass. 

 

ddf

 

Delwin D Fandrich

Piano Design & Fabrication

6939 Foothill Court SW, Olympia, Washington 98512 USA

Phone  360.515.0119 — Cell  360.388.6525

del at fandrichpiano.com  <mailto:del at fandrichpiano.com> — ddfandrich at gmail.com

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Gene Nelson
Sent: Friday, May 18, 2012 7:26 AM
To: pianotech at ptg.org
Subject: Re: [pianotech] S&S K(52) Restoration

 

Ribs fanned and perpendicular to long bridge?

Does Z structure define rib length in that area?

Gene



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