impedance for 99

[Ron Nossaman]

   I think the ability to measure the impedance of a soundboard before
installing it might be very helpful, if for no other reason that to verify
that the modeling works properly.

*Yep, you would surely have to calibrate the model from an existing strung
piano for any of this to mean anything.


>Jory:  For somebody that claims to be a "basement tinker" you have an
amazing grasp of the fundamentals.  

*Just trying to pay attention.

As you go up in frequency the inertia of the cone (from the fact that it has
mass) causes the cone to begin to break up.  That is, it is no longer moving
as one unit.  The concentric rings on the cone are an attempt to limit the
number of modes that appear on the cone, much like a filter or impedance
matching device.  About the only point you left out was the limitations of
the linear motor.  

*I figured that the limitations of the piano strings as a driving source to
the soundboard was analogous enough to not get into it. 



At some point the backpressure on the cone, the interia, and so forth
overcome the motors ability to control the cone motion.  When this happens
distortion increases greatly.  Lower impedance voice coils, bigger magnets
on the motor, amplifiers with lower output impedance (read:  big wattage)
amplifiers, sophisticated feedback schemes are all attempts to exert more
control over the moving cone.  

*Gee, this does sound a lot like soundboard phenomena... higher tensions,
harder hammers, cutoff bars, tone resonators, diaphragming, etc.

Are you sure you don't have a degree in acoustics from Georgia Tech?

*Aw come on now, gimme a break. The educational system delayed my education
long enough as it was, just getting through High School. I'm still way
behind schedule.


>I like the stuff you, Doug, and Del are doing.  Maybe you guys should form
a startup....
>
>Jory

*Personally, I'm having a ball. I've learned enough in the last six months
to really begin to realise how much of this stuff we don't know... yet.

 Ron