The Duplex affect --an experiement

[BobDavis88 at aol.com]

In a message dated 11/13/2007 9:50:57 PM Pacific Standard Time, 
davidlovepianos at comcast.net writes:

Did you do the experiment blind? i.e. did the listeners (and player) know 
when the tape was on or off?  You need to do that to really legitimize the 
results.  

David,
 
It was at the end of the meeting, so it was somewhat ad hoc. However, I 
suggested the exercise because of my own experiments in this area, and because I 
didn't agree with recent talk about the duplexes not being worth much. The first 
piano on which I had practical use for it was a Steinway D some years ago 
that had been braided all the way up the tenor at the factory. There was 
something unsatisfactory about the tone, and I was poking around, and noticed the 
braiding. I pulled it out and was surprised at the improvement.
 
Back to our meeting - We found that the difference with/without the tape in 
the tenor was so obvious that I have no doubt what the results would be not 
looking. The differences in the other sections were more subtle, and I too would 
like to repeat them with more controls. Our sense was that the tone just 
sounded freer, bigger, and more interesting with the duplexes open, even the upper 
ones, but I'd be happy to try it again when we have more time.
 
It brought up the question of whether the duplexes were compensating for poor 
soundboard design. This would be a hard one to control for, but my 
off-the-cuff feeling was that a more efficient soundboard would just make the effect 
more obvious. Piano tone relies on the interaction of so many things that it's 
hard to change just one, and be satisfied that we have enough information to 
draw useful conclusions. Other variables in the duplex experiment might be the 
distance from the piano at which the sound change was noticeable, and the effect 
of hammer voicing, and the phase of the moon, and....
 
Bob Davis



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