voicing

[Ron Overs]

Hi list,

Things got a bit quiet while the KC convention was in progress, but I see 
everybody's back on deck again.

Richard Brekne wrote:

>. . . . . . . I  have not seen a soundboard that has both too little down 
bearing and at the same 
>time plenty
>of crown.

We have - but only once!

In 1990 we rebuilt a 1925 New York S&S D (which had been 'rebuilt' a few 
years earlier). This piano had 8mm of crown in the middle of the 
soundboard, while at the same time, the down bearing was effectively zero 
(all measurements were taken with the piano strung and at pitch).

Since the bridges were completely split we manufactured new bridges.  The 
scale design was completely revised to even out inharmonicity and 
percentage of breaking strain (our first application of this technique on 
a model D). String lengths were marked out exactly to the calculated 
optimum lengths on a template.

The previous 'rebuild' had been undertaken by 'repairing' the bridges 
with oversize pins, ie. balance rail guide pins - very nice it looked too 
with all those decorative splits!

The original bridge height was 36mm. After setting the new bridge height 
for six millimetres of down bearing unstrung at the centre of the long 
bridge (ie. at note G35), the new bridge height measured 40mm at this 
point. The resultant sustain of this piano was quite outstanding. I have 
always suspected that taller bridges contribute to increase sustain time.

>.. I guess I need to be more precise. String deflection at the bridge 
>is measured
>before easing off string tension, and then again afterwards. The 
>difference gives a
>reading of how much the board rises with tension off. ie. crown. Does this 
>jive with
>your meaning of crown ? If not I would like to hear how you check crown.

Exactly Richard! Further to this, we measure sound board crown while the 
piano is still at pitch. Placing a straight edge across the piano from 
rim rim, a series of measurements are taken measuring down from the 
straight edge to the soundboard. The straight edge is moved across the 
piano to take readings from all over the sound board. A clear indication 
of the contour of the soundboard can be ascertained.

Ron Overs
Sydney

Email: ron@overspianos.com.au
Website: www.overspianos.com.au