Single string versus full Unison

[Jim]

Dear List:

Since I have had some feedback from a few of you, I thought it would be
wise to send some very recent data - like tonight.  I just completed a
test where I had tuned the three strings of a unison about as close as I
could. I tested in the order from left to right.  Here are the results.

Note F#58     Left    Center    Right   Full Unison
               -.18    -.04      -.02    -.49
                .16    -.22      -.17    -.39
                .07    -.08       .28    -.59
               -.23     .01       .10    -.79
                .03    -.04       .01    -.62
                .05    -.09       .08    -.73
               -.01    -.05      -.15    -.83
                .01    -.01       .06    -.35
                .08     .07      -.05    -.46
               -.05    -.03       .10    -.64
              ================================
                .07    -.48       .24   -5.89

Averages        .01    -.05       .02    -.59

I did 10 examples so that they could be added up at each column and
then the three single string column sums could be averaged and then
compared to the average of the full unison column.

I was very careful to try to keep the key pressure the same for each test
across the row.  I know this is not as scientific as if I had a weighted
striker.  I don't know why I was always surprised when I got to the 4th
column to hear that the tone was much louder.  We know from previous tests
and everyday tuning knowledge that a tone is sharper at first than it is
later, and that a tone played softer will show a slightly lower pitch due
to decreased tension caused by decreased amplitude.  If the added
pressure of the wedges created a measureable increase in tension, then the
single strings as a result should sound lower in pitch (kinda similar to
when a single string breaks, the notes around it go sharper - only
it's the reverse when tension is added, the other strings should go
flatter).

I'm sure this data is up for interpretation, but at the present time I can
still only agree with Virgil Smith.

Jim Coleman, Sr.

PS  The measurements were taken using the measuring ear of the RCT.
It is still difficult to see these differences on the SAT and
sometimes on the RCT when looking at the movement of the display or
rotation of the lights.  I don't know exactly how the counter on the RCT
works, but the figures above are still pretty consistent.  There
doesn't seem to be any lowering of pitch due to the repeated playing
of the note.  During the bottom two rows, I deliberately tried to play a
little harder to see how much effect that would have.  The variations
seem to be random.  I expected to see pitches rise slightly.  It
didn't happen.