Soundboard Thoughts

[Susan Kline]

Curiosity aroused:

The "killer octave" has equal lengths of rib fore and aft of the bridge, and
the tone has trouble there. Has anyone ever tried making the ribs the same
length fore and aft, but making them much lighter and more flexible on one
side than on the other?

What fun ... reminds me of that great string seating thread.

Susan
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At 10:48 AM 12/7/97 -0600, Ron Nossaman wrote:
>Hi Newton,
>
>Right, as usual, by gosh. I went out and looked again. The treble has more
>rib length behind the bridge, the tenor and bass has more in front. Guess
>where the transition point is where the rib length is equal on both sides.
>%-) Yep, smack in the "killer octave" problem area. This makes a lot more
>sense than my original thoughts.
>
>With a couple more brain cells activated, I checked out the monster tone bar
>idea again. It looks like a roughly similar ratio of rib length fore and aft
>of the bridge can me maintained through the whole scale at a cost of between
>fifteen and twenty percent of the total soundboard area. Seems like a big
>chunk, but the tone bars I see installed in that area in existing
>instruments already indicate that the front bass corner doesn't have much to
>give toward tone production anyway, so maybe the hoped for improvements in
>sound production would outweigh the loss of area. Since that extra area in
>the bass is fighting the board movement in the treble, I'd expect the net
>effect of the change would be positive. We would still get the proportional
>narrowing of the board (sort of) corresponding to the frequency of the sound
>produced at that point on the bridge, so the rest of my original scenario
>still seems logical. This modification would also reduce the torsion on the
>bridge with humidity changes and probably maintain a crown in the high
>tenor/low treble better than the current configuration. I like it. It's
>simple, logical, and pretty, at least until someone shoots it down with
>another "faulty premise" correction. %-) It's a better fit now, I think,
>thanks for setting me straight.  
>
>Ron
>
>At 10:01 AM 12/1/97 -0500, you wrote:
>>Dear Ron,
>>
>>If you watch drummers you will notice that they play along the side of
>>the head, not the center.  If a rib cuts a soundboard in half, you will
>>loose tone and power because of the cancelling effect of the equally
>>split bridge.
>>
>>Some of your other thoughts sound good.  Perhaps DDF will jump in since
>>he seems to know more about soundboards than anyone else I know.
>>
>>Have a nice week.
>>
>>	Newton
>>	nhunt@jagat.com
>>
>
>
> Ron Nossaman
>
>
>

Susan Kline
P.O. Box 1651
Philomath, OR 97370
skline@proaxis.com

"Cheer up! Things may be getting worse at a slower rate."
			-- Ashleigh Brilliant