Voicing Steinway-need sustain!

[Delwin D Fandrich]

Lance Lafargue wrote:

> I have a customer with a five year old B in need of sustain in the lower
> treble section.  He first needed volume, I added hardener to the low
> shoulders, got the volume and clarity on the attack, but the sound drops
> off immediately and we have no sustain on several of the notes.  I will
> next check the strike point in that area, although the high notes are
> right.  When I voice Abel hammers, I stick the needle deep down the
> shoulder along the molding for sustain, but was reluctant to try the same
> on the Steinway hammer.  Any suggestions?

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Lance,

Before getting to the probable cause and solution to this problem, there are
some possibilities you might want to check out first:

1)    Hammer strike point.  The Model B is one of those pianos with what appears
to be a wandering V-bar.  Check the strike point -- if you can -- by moving the
action in and out and listening.  If you can't get enough movement this way you
may have to use a sample hammer on a test shank.  While you're at it, have you
verified that the surface of the hammer is square to the string set?

2)    Sting termination at the V-bar.  Are the strings reasonably level?  Is the
V-bar shape correct?  Is the string termination angle sufficient to adequately
terminate the speaking segment of the string?  This is always suspect with
pianos using front tuned duplex stringing that exhibit sustain problems.  Most
of the energy that bleeds into the duplex segment is lost and cost the piano
sustain time.

3)    String termination at the bridge.  Are the bridge pins reasonably tight?
Is the bridge notching reasonably well done?

4)    Hammer voicing.  Lacquering -- any form of chemically hardening -- does
not generally help sustain time.  Indeed, it often exacerbates the problem since
the harder hammer will excite higher string partials, the energy of which
dissipates more quickly both into the soundboard and into the plate mechanism.

5)    The bell bolt.  Is the bell bolt snug and secure?  Don't get carried away
with this, it just needs to be tight enough to put some tension on the plate.

6)    String bearing.  Is there a reasonable amount of string downbearing on the
bridge?

And now for the most probable cause of the short sustain time of this piano.
The soundboard impedance is simply too low.  There isn't a lot of energy in
these strings to begin with.  What energy that is there is simply being bled off
too fast.  Part of it is going into the the plate via the tuned duplex system,
but most of it is simply being dissipated into the soundboard too quickly.  This
is a particular problem with piano that use compression crowned soundboards.
And especially when those soundboards are thinned out in the treble sections as
they are in the Model B.  Making the soundboard thinner does make it somewhat
more flexible, but it also decreases its ability to sustain crown and/or
maintain the required stiffness to impede the transfer of energy from the string
to the board.  Hence the short sustain time.

There is a patch that you can at least try.  Adding mass to the bottom of the
bridge -- as is also suggested by David McCord -- will increase the impedance of
the assembly somewhat.  It's not the same as restoring the stiffness, or the
springiness, of the soundboard assembly, but it can sometimes help.  It is the
springiness component of the impedance relationship that is lost as the
soundboard wood fibers deteriorate under the stress of high internal
compression.  The mass component stays the same.  Still, adding mass can at
least increase the sustain time of the upper partials.  If you're going to do
this, you should do it before you do much more hammer voicing.  The tone quality
will also change and may affect what you need to do to the hammers.

The real solution, of course, is to replace the soundboard.  In the process, it
would be helpful if you were to redesign the rib scale to prevent this from
happening again in the near future.  At the same time it might be a good idea to
straighten out some of the string scale problems that exist in this section of
the piano.  When these two things are taken care of, things like the
super-critical hammer strike point are no longer so critical.

Regards,

Del