Two Questions in One Post

[Delwin D Fandrich]

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  ----- Original Message -----=20
  From: Ray T. Bentley=20
  To: Pianotech=20
  Sent: October 12, 2000 6:41 PM
  Subject: Two Questions in One Post

  Secondly,  I learned many years ago that we hear no fundamental in the =
lowest notes of pianos.  But I was under the impression that perhaps =
there would be fundamental heard in the lowest notes of concert grands.  =
I had a few minutes after the last tuning of a Steinway D that I =
prepared for a concert, and used the RCT Pianalyzer to measure the =
harmonics of the lowest octave.  I found that no fundamental was =
recorded until A1.  This means that even on that piano there is no =
fundamental pitch heard on the entire first octave of the piano.  Have =
any of you done any extensive research on this?  Is this true of most =
concert grands, or only on the one I happened to try this on?

  Ray T. Bentley, RPT
  Alton, IL

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Ray,

Yes, there will be some measurable and audible energy at the fundamental =
frequency of even A-1in a piano such as the Steinway Model D. Perhaps =
not as much as we would like, but there will be some. Exactly how much =
there will be in this particular piano will be a function of how well =
the soundboard is performing, the condition and voicing of the hammers, =
the condition of the bass strings, etc.

You are not able to get an indication using your RCT for a variety of =
reasons. First, I'm not sure the RCT is set up to give any indication at =
all at frequencies as low as 27.5 cps. You'd have to check with Dean =
Reyborn on that. Secondly, I doubt that the microphone in your computer =
works very well at these frequencies. It takes a pretty good microphone =
to give good, uniform frequency response through the entire audio =
frequency band -- especially down in the low bass. Even quite good =
professional audio mikes often exhibit substantial roll-off at =
frequencies below 50 to 100 Hz. I don't know about the rest of the audio =
section of your computer -- the electronics portion should be pretty =
easy to get right these days. Still, I expect it is some removed from =
that found in professional measuring equipment.

On a broader scale, how much energy there will be in the audio output of =
the piano is dependent on a number of closely inter-related factors. =
Some of these are:
  a.. The speaking length of the strings. Obviously, longer strings will =
have a greater potential to develop energy at low frequencies, but there =
will be some fundamental energy even in quite short bass strings.
  b.. The length of the string backscale. If the back scale is very =
short, the motion of the bass bridge will be so restricted that most, or =
all, of the fundamental energy will be blocked at the bridge.=20
  c.. The stiffness to mass relationship of the soundboard. If the =
soundboard is not adequately compliant it will not move easily at very =
low frequencies.
  d.. The location of the bass bridge relative to the inner rim of the =
piano. If the bridge is located very close to the inner rim, the =
soundboard will not be free to move adequately at very low frequencies =
to develop enough sound energy for us to hear.
  e.. The construction of the bass bridge. If the bass bridge is mounted =
on a cantilever, some percentage of low frequency energy will be =
absorbed just moving the cantilever. Bass bridge cantilevers tend to =
filter out very low frequency energy.
  f.. Design of the string termination at the plate. Other factors being =
similar, designs using vertical hitchpins -- i.e., Baldwin, Walter =
grand, etc. -- have greater potential to develop more acoustic energy in =
the low frequency tone envelope than do designs using the older, more =
conventional hitch pin arrangements.
  g.. The physical characteristics of the string. If the core wire is =
excessively large, relative to its length, energy at very low =
frequencies will not be excited in the string. Energy at higher =
frequencies will overwhelm low frequency energy.=20
  h.. Excessively hard/dense hammers. These hammers tend to excite =
higher frequency partials at the expense of the fundamental.
There are probably a few other things I'm forgetting here -- but it's =
late and I'm tired. This should give you at least a general idea of what =
is involved in developing acoustic energy at low frequencies.

>From the looks of 'modern' piano design, little effort has been put into =
this aspect of piano performance. Still, in most pianos, with the =
obvious exception of some rather badly designed sub six-foot pianos, =
there should be some measurable and audible fundamental energy within =
the tone envelope.

Regards,

Del
Delwin D Fandrich
Piano Designer & Builder
Hoquiam, Washington  USA
E.mail:  pianobuilders@olynet.com
Web Site:  http://pianobuilders.olynet.com/

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