Pinning, Friction, Tone, etc.

[James Ellis]

I have been reading the various posts on this and related subjects, and I
want to throw out a few words of caution.  Most of you already know what I
am about to say, but I'll say it anyway.  

1. The fallacy in all the common tests for pinning tightness is that one
side might be tight, and the other loose.  Don't be fooled by this.

2. Recording the true sound of a piano is not an easy task.  Microphone
placement and room acoustics are critical.  Cheap mics properly placed will
produce superior results to superb mics badly placed.

3. In doing tests with spectrum analyzers, be careful that you introduce
only ONE variable at a time.  Room acoustics play a big part in the overall
picture.  Move the piano a few inches, and the spectrun will change.  Move
the mic an inch, and it will make a big difference due to standing waves at
the various partials.  I can't stress this enough.  For tests like this,
you need to be in a sound chamber, or out in an open field away from all
noise - conditions that are just not practical.  Just be sure that nothing
moves even a fraction of an inch between tests that you want to compare,
and that includes people who might be standing around.  Furthermore, it is
nearly impossible to get a true picture of the sound spectrum of the piano,
because any mic placement you use will give you a different picture.  Even
if you are in a chamber, the piano's soundboard covers a large area, and
there are all sorts of standing waves in the air at the higher partials.

Sincerely, Jim Ellis