Killer Octave Question

[Isaac OLEG]

Hello,

What an interesting thread !

Specifically, are not compression crowned systems more responsive
under less bearing, because the tension is supposed to be build
internally in the soundboard to begin with ? (nice theory anyway !)

Talking about the arch effect, I see no mension of the "system effect"
that is due to the gluing of the board on its perimeter, this part of
the process is certainly building some resistance and stiffness in the
board, not an arch idea, but the global assembly is for sure something
with different characteristics than if for instance only the rib's end
where fixed.

Beside, I was not aware of the lever effect from the treble fulcrum -
that is interesting.

 I installed once a metal brace, and it add power (as with more front
bearing) and gave a thicker tone, not in the killer zone exactly, but
slightly higher mostly (around the last frame brace). I did not find
it add sustain time, but the result was good.

The crown in the treble did not grow up a lot, as seen with a
comparator (0.15 mm more with the turnbuckle very tight), on a S&S mod
C - I felt that the board stressed too much after that, and indeed
hardening the system too much does not seem to produce good tone.

The accessory is very efficient but may be tuned accordingly to the
remaining of the bearing in the zone. I was instructed to string
without tension on the brace, and regulate it while voicing, but I
wonder if it may not be more efficient to regulate the bearing with
the turnbuckle yet tensioned.

Best regards, and I enjoy reading.

Isaac OLEG


> I might add that you are being very generous with your
> numbers. I doubt many
> compression-crowned soundboards have anywhere close to a
> 40' radius on
> installation.
>
> Del
>
>
> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives
>