Digitals-- (ACOUSTIC?)

[Steven D. Majewski]

The recent discussion on coupled strings is a small, but good example 
of the kind of complexity that isn't currently caught by digital models
of piano sound. 

The simple, cheap portable keyboards have a single sampled waveform
which they alter in pitch and intensity. 

The more expensive models (I am told) have several samples taken at
different octaves and mix them together as some weighted average determined
by the note. 

I don't know whether Yamaha and other digital keyboard mfgrs. are using
other keyboard dynamics to alter the waveform -- to give a different tone
color as well as volume to notes played with a differnet touch -- but I've
certainly seen papers on that sort of stuff  -- it ought to be the 
state of the art for the more expensive models. 

 I get the distinct impression that Yamaha, et.al. consider these 
details competitive trade secrets. and are shy about disclosing 
any info on the algorithms used. 


( The other thing you pay for as you move upscale is a better, more 
 resistive ( more "mechanical" less digital ) keyboard, and of course,
 better PSO furniture! ) 

1st generation of keyboards were literally "synthesizers" -- they 
synthesized a waveform, first by analog additive and subtractive 
(filtering) circuitry, and then by FM or digital synthesis. 

2nd generation: (most of the current crop) digital wave tables 

The next generation is definitely combining the two -- wave tables 
combined and modified according to other input parameters. No need
for any fuzzy logic here. Piano's are complex but determinate machines. 
All we need is to add a couple hundred parameters to the model 
( velocity of the keystroke, other keys being played in neartime, etc. )

[ I've heard the tube vs. solid-state organ sound difference ascribed 
 to mechanical coupling in the grids of tubes -- they vibrate with the 
  sound generated. ] 


I think digital will eventually ( another 20 years? ) get there. 
On the other hand, analog computers are often more effecient for
some problems -- what is the state of the art for electro-mechanical 
keyboards these days ? 



- Steve Majewski