In the 05.05.10 MMD Bruce Mercer wrote:

  > My question is whether or not the two types of moldings, American
  > vs. European, are interchangeable.  The backchecks look very
  > different to me and I'm not sure that the hammers can be
  > interchanged without changing the backchecks as well.  This is the
  > first grand that I have encountered using this type of hammer
  > molding.  All others have used the traditional "American" type of
  > molding.  I was told that Knabe "cheaped out" by using this type of
  > molding.  But that is something I doubt.
  > ....
  > At one point I had considered using Renner hammers but was told by
  > another rebuilder they are too hard and very difficult to voice.
  > Is this true?  Since American Piano Supply is now defunct, I no
  > longer know where to buy these hammers at a wholesale price.

Being a veteran piano tech for many years I have replaced many a hammer
and the more I learn the more I realize what I don't know.  Nevertheless
here is the generic synopsis:

The molding has two primary properties.  The first is weight.  Maple,
for example, is generally heavier than mahogany.  Walnut is also
somewhat heavy.  I have seen some old pianos that originally had
relatively light actions become too heavy because someone used
inappropriate hammers.  Most modern pianos today seem to be going with
mahogany  although I see maple predominantly in uprights.

The second factor to a lesser extent is tone.  Mahogany for example
tends to have a slightly warmer, "woody" sound and is what I prefer for
most rebuilds.  Maple hammers tend toward a slightly brighter attack.
Nevertheless maple hammers have very nice qualities as well.

All of the above can be greatly influenced by how much felt tension the
hammer has.  My philosophy is that a higher felt tension to begin will
provide more stable voicing in the long run.  My experiences with low-
tension hammers (Steinway for example) is that I need to continuously
maintain the smoothness of the voicing.  To get a brighter tone I also
must use a lot of hardener rather than taking full natural advantage of
the felt itself.  In radical contrast, many Asian pianos today,
particularly those from China, tend to have seriously high felt tension
making them obnoxiously bright.  Scaling of course is also a factor in
this.  These rock-hard hammers have their own set of issues.

I personally prefer Able hammers for rebuilding.  Right out of the box
they sound very even and the only significant voicing I need to perform
is brightening the last octave and smoothing out the bass/tenor break,
both of which are issues that would have to be dealt with no matter
which hammers you use.  If the piano originally had very light hammers,
I suggest requesting their special "Able Lights" (not a diet drink or
tobacco product).  The last set of these I installed was on an 1889
Bechstein, and the hammer weight turned out to be perfect.  Renner
hammers also get a thumbs up.  I installed a set of Renner Premium Blues
on a Steinway D in a performance hall just a few months ago and have
gotten rave revues from professional performers.  I am rebuilding an
action for a Steinway "M" right now but I think I will go with
the Able this time.

As far as back checks go, if they look worn, old, or otherwise appear
that they won't last another twenty years, replace them. They are not
all that expensive, and you will be glad you did.  Make sure you order
the ones with the wires, not just the heads.  I recommend the Renner on
these.  If you have an unusual size or shape to deal with, consider
sending in a sample.  Also, unless it is a fairly young piano with low
mileage, by all means replace the hammer shanks while you are at it.
Another expense, yes; but it will make a world of difference when it
comes time to regulate the action.  More than likely the knuckles and
center-pin bushings have seen better days anyway, and it will be a more
professional job.  Either Renner or Encore on these.  As a side note, I
give a big thumbs-up on Renner wippens too.

In regards to American Piano Supply, they are still alive and well.
They were purchased by Schaff but still operate independently.  My
favorite supply company these days is PianoTek.  They are a little more
expensive on some things, but the quality is golden. Nice folks too.

Rob Goodale, RPT
Southwest Piano Technologies
Las Vegas, NV