agraffes on bridge?

[Brian Henselman]

I posted this message earlier because I always suspected that Sohmer's
bridge agraffes were providing "upbearing".  Your response confirms that
they don't provide downbearing.  However, if the bridge agraffs have
upbearing, how does this comport with the treble section, which has
traditional bridge pinning?  Doesn't the upper "traditional" treble have
downbearing?  Isn't it really strange to combine upbearing and downbearing
on a bridge?

What does this do to pitch alteration?  My "home-grown" aural pitch raising
formulas rely on increasing the load throughout the soundboard as tension
increases.  What do we do if the agraffs actual lift the bridge during the
addition of  string tension?

Speaking of strange effects during pitch raising... Ever notice what happens
to the pitch on a square grand while pitch raising?  The side bearing
changes direction on the other side of the treble bridge.  You're leading
the pitch up during a pitch raise on the tenor side of the treble bridge,
and then all of a sudden your on the other side of the "bend" and now you're
chasing the pitch up!

This may not be quite 2 cents worths...

-Brian Henselman,RPT

-----Original Message-----
From: JIMRPT@AOL.COM <JIMRPT@AOL.COM>
To: pianotech@ptg.org <pianotech@ptg.org>
Date: Wednesday, September 22, 1999 8:06 PM
Subject: Re: agraffes on bridge?


>
>In a message dated 9/22/1999 6:07:02 PM, musicmasters@worldnet.att.net
writes:
>
><< "I've never measured the downbearing on an old Sohmer grand to
>confirm that it was providing downbearing. ">>
>
>Bran H.;
> You can't measure "downbearing" on the portion of Sohmer bridges because
>there is none :-)   Sohmer agraffes give an 'upbearing' at the bridge.
>
><<"Even if does,  wouldn't agraffs on the bridge risk buzzing during the
>winter if the crown was particularly flat?">>
>See above :-)  I don't think I have ever had problems with a Sohmer bridge
>agraffe "buzzing" the main problem with the thingees is that so equipped
>pianners have a 'nasal' kinda muted metallic sound...not unpleasant but not
>'rich' either.
>Jim Bryant (FL)
>
>