More responses needed

[David Love]

Because the ribs run counter to the grain of the soundboard and effectively 
transmit vibration across the board (including across a crack in the 
soundboard), there is little loss in tone production.

David Love


>From: Wallace Scherer <p003520b@pb.seflin.org>
>Reply-To: pianotech@ptg.org
>To: pianotech@ptg.org
>Subject: More responses needed
>Date: Thu, 3 May 2001 12:41:30 -0400 (EDT)
>
>Dear list members,
>
>A recent discussion I started about applying epoxy to cracks in the
>soundboard of an old Winter piano which had strings and tuning pins
>replaced by another technician about 5 years ago, led to the conclusion
>by about 5 or 6 people who responded that repairing cracks in soundboards
>is mainly for cosmetic reasons and will not affect the tone significantly.
>
>To me this goes against the whole purpose a soundboard exists! Take the
>analogy of a speaker cone:
>
>Lets say that we have a radio or other sound producing device whose sole
>output is through a 15" woofer loudspeaker. If we then take a razor blade
>and make a series of randomly spaced  slits about 2" to 3" long around
>the sides of the speaker cone, wouldn't we expect the tonal quality of
>the speaker's output to be diminished considerably? And if, then, we
>proceeded to seal those slits in some manner so as to come close to
>having the speaker cone intact again, wouldn't we expect an improvement
>in the sound from when the cone had the slits in it?
>
>The reduction in sound (volume, tonal quality, etc.) of the speaker with
>the slits is due to its not being intact - the movement of the cone does
>not faithfully reproduce the sound it is supposed to make because its
>surface area does not respond uniformly.
>
>In like manner, especially in the lower frequencies of the bass notes of
>a piano, when the larger area of a soundboard must faithful reproduce
>those lower frequencies and transmit them to the air without
>interruption, if the surface area is broken up by cracks, the movement of
>the soundboard is impeded, therefore greatly reducing the volume of the
>sound reaching the hearer.
>
>Because of the basic physics of sound production, it therefore does not
>make any sense to me that repairing the cracks of a soundboard (assuming
>that the bridge, ribs, strings, etc., are all in good condition) would
>not somewhat improve the sound of the bass section.
>
>Since so few of you responded to this, I would like to ask more of you to
>respond, especially those who have had considerable experience in
>repairing cracked soundboards.
>
>The question is this:
>
>Assuming that the ribs, bridge, and strings are all good, would only
>repairing 10 fine, but rather long (10" or more) cracks in a soundboard
>make a noticeable difference in the bass section of a piano? (Let's also
>asume there is little or no crown.)
>
>Thank you.
>
>Wally Scherer
>Palm Beach County, Florida
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>

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