SW heresy?

[Farrell]

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Ok, here goes: I'm going to paraphrase David Stanwood from memory. Scary =
thought.

I've gone to his classes several times and my recollection is that his =
SW curves are not based on any mathematical principle. His SW curves do =
not have anything to do with the original hammer weights. But rather, =
his SW curves were developed from analyses of THOUSANDS of "very good" =
pianos.

Over a period of ten (or more???) years, David sought out high quality, =
good sounding pianos. "Good" meant good tonal qualities along with =
evenness along the entire scale. He would borrow the action from these =
pianos and analyze the SWs (among other action parameters also).

David is a smart guy, with good ears, and I suspect a good judge of what =
a good piano sounds like. IMHO, being that his curves were likely =
developed mostly from Steinways, and the fact that your piano is a =
Steinway clone, I have little doubt that it would be a better basis to =
base your SWs on a Stanwood curve rather than where some hammer maker =
happened to run a saw across a set of hammers.

I've done several pianos to his curves and have been thrilled with the =
results. Ric B. and others could offer more experienced advice than I as =
to which curves to follow. However, with your 9-foot piano, I would =
imagine you will want one of the heavier curves.

Terry Farrell
  ----- Original Message -----=20
  From: Sarah Fox=20
  To: Pianotech=20
  Sent: Sunday, August 22, 2004 1:30 AM
  Subject: SW heresy?


  Hi all,

  Thanks for the advice about techniques to even out the SW curve!  That =
should give me a variety of techniques to use/combine in order to even =
out the jags.

  But the question is one of what my target curve should *really* be.  =
Hmmmm....  My thoughts:

  The unmodified SW curve is obviously very linear.  (Yes, I know what =
linear means.  I "minored" in mathematics, sort of -- except that my U. =
didn't officially recognize minors).  Stanwood's curves, OTOH, are all =
concave downwards.

  I was advised off list that I shouldn't force the hammers to =
artificially conform to a standardized Stanwood curve but to simply even =
out the jags to make the action smooth from bottom to top.  There's =
something to be said for this idea.

  But as I got to thinking about the SW curves, I was wondering, where =
do they REALLY come from?  That is, where does the shape come from?  I =
suspect the hammer manufacturing people might be able to enlighten me as =
to this.  (Ray???)  I'm *guessing* that the felt is denser than the =
molding, and when the hammer becomes skinnier, it loses more felt than =
molding, resulting in a more precipitous dropoff in weight at the higher =
end.  This would occur with a constant hammer length and a linear =
variation in hammer and molding (and felt) width.  Am I anywhere close =
on this idea???

  Contrast this function with other functions that might actually relate =
to optimal hammer mass:  String length and mass both decrease with the =
note number, with a function that is concave upwards.  Note frequency =
increases with a function that is concave upwards.  Note period (inverse =
of frequency) increases with a function that is concave upwards.  The =
Stanwood curve seems rather meaningless with regard to any of these =
functions.  For instance, it might be good to match hammer mass to =
string mass by some proportion.  Right?  As the scale goes up, string =
length and mass approach an asymptote of zero.  Therefore, shouldn't =
hammer mass approach an asymptote of zero?  Instead, the curve starts =
taking a dive in the treble.  If the scale went up well past 88, hammer =
mass would eventually crash to zero.  Because these curves do not have =
the same form, the relationship between hammer and string mass is =
anything but constant.  That doesn't make sense.

  So is this something that is the way it is just because of tradition =
-- because the cauls are built that way, and that's what ya' get? =20

  Now that I look at my linear SW curve (with jags), I'm wondering if =
this isn't REALLY a closer match to something meaningful (like string =
mass) than the idealized Stanwood curves.  Any thoughts, y'all?

  Peace,
  Sarah



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