Heimlich this Henry F. Miller

[Ryan sowers]

Is it the actual height that is responsible for the increased sustain or is 
it, perhaps, that the increased mass of a taller bridge raises impedence and 
increases the sustain? I've seen sustain increase significantly in pianos 
where weight has been added to the bridge.

Ryan Sowers, RPT
Puget Sound Chapter, #985
Olympia, WA



>From: Ron Overs <sec@overspianos.com.au>
>Reply-To: pianotech@ptg.org
>To: pianotech@ptg.org
>Subject: Re: Heimlich this Henry F. Miller
>Date: Sun, 29 Jul 2001 23:11:30 +1000
>
>Guy,
>
>I too can only concur with Roger that planing the bridge might not be
>in the best interests of the tone quality.  Furthermore, planing the
>bridge height may reduce the string offset across the bridge to a
>unacceptable degree. Either a half round bar or a hard maple bearing
>(which could be conveniently profiled to achieve the desired down
>bearing) might help you to achieve the results you're after. On many
>occasions we've used hard maple bearings with bearing cloth glued
>over them prior to restringing. The maple is easily profiled to set
>the appropriate bearing, while the felt covering damps the back scale
>sufficiently without listing felt. I'm not a big fan of undamped rear
>string scales if they are untuned.
>
>Bridge height does seem to have a bearing (if you'll forgive the
>term) on the sustaining qualities. Low bridges tend to encourage a
>short shocky tone. I prefer  the bridge height to be at least 30 mm
>and nominally around 34 mm or over. Of course, the rigidity of the
>ribs will also influence sustain, but the bridge has a significant
>influence.
>
>Last year I inspected a contemporary concert piano designed by a well
>known 'designer'. The 24 mm high bridges in the middle of the long
>bridge resulted in perhaps the worst case of short and shocky tone I
>have heard from a modern concert piano. Clearly, this piano was
>designed without due consideration being given to the relationship
>between the plate and sound board panel height (which will ultimately
>determine the nominal bridge height). We must always be careful about
>the design parameters which may or may not influence the tonal
>qualities. Bridge height, rib strength (and length), plate thickness
>and rim rigidity are all factors which must be considered together to
>achieve the desired sustaining qualities.
>
>Our piano no. 003 (the one exhibited at Reno) had 34 mm high by 35 mm
>wide bridges, while piano no. 001 had just 30 mm high by 35 mm wide
>bridges (most other sound board specs were pretty much identical).
>The increase in sustaining qualities between the two pianos was
>noticeable.
>
>Regards,
>
>Ron O
>--
>Overs Pianos
>Sydney Australia
>________________________
>
>Web site: http://www.overspianos.com.au
>Email:     mailto:ron@overspianos.com.au
>________________________


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