Recrowning/arched spruce demo

[Richard Moody]

----------
> From: rhohf@idcnet.com
> To: pianotech@ptg.org; pianotech@ptg.org
> Subject: Re: Recrowning/arched spruce demo
> Date: Tuesday, June 03, 1997 8:03 PM
> 
> 
> First, a matter of semantics:  neither the arched spruce board nor
a piano 
> soundboard are amplifiers.  Amplification implies an _addition_ of
energy to a 
> signal.  A stereo amplifier takes a weak signal and increases it by

> electonically _adding_ energy.  Both the arched spruce and piano
soundboard are 
> _transducers_.  Transduction involves the passing of energy from
one element of 
> a system to another _without_ the addition of energy.  If a sound
gets louder, 
> it means that the transduction changes in some way.  I mention this
just for 
> clarity--it's a good idea to use the proper terms when we can. 

	I forgot what the energy is called that is in a compressed spring or
an arched sound board.  But as long as we are on semantics, might
this "latent" energy some how  _add_  to the sound? Of course the
point is  the sound gets louder whether from amplification or
transduction.  Why this happens is what makes it interesting.  
 
> 
>
> Here is what I think is happening:  under some circumstances, a
piece of wood 
> can be induced to vibrate with a standing wave.  

Perhaps a clarification of the term "standing wave" could follow.  I
might be confusing this with resonance.  If that arched demo could be
activated such as by bowing, it should produce a note of its own.  Is
this related to a standing wave? 
 
> Doing this stuff is fun and many more experiments are suggested by
this, but 
> someone on the list asked, "What does this mean in a real piano?" 
The answer 
> is, "Absolutely nothing."  

	But then why are all sound boards crowned? 

Richard the Wonder(ing) Kind