SV: [sdiy] New and Improved Buchla waveshaper analysis

[karl dalen]

--- Aaron Lanterman <lanterma at ece.gatech.edu> skrev:

> recall seeing, except I remember the Serge gave a more rounded transfer 
> function.

Suposedly of non linearities of the shaper.
The dual transistor shaper i mentioned earlier
do very nice rounded shapes with a triangle wave
as input.(suposedly working in the more nonlinear 
region of the transistors.

Its essential to have this to be able to get
more of the DX7'ish FM sound, ie less odd
harmonics.
 
> Here's my two new soundfiles:
> 
> http://users.ece.gatech.edu/~lanterma/buchla_timbresweep.wav

Sounds hollow.

> http://users.ece.gatech.edu/~lanterma/buchla_symmetrysweep.wav

Thats more like it, FM, sharp and nice!

> sine wave as input, and then ran an FFT on that, and then >stacked up the 
> results. In the below files, on the left you see a plot of the >1st, 3rd, 
> 5th, and 7th harmonic amplitudes (oops - for the symmetrysweep, >I should 
> have plotted the even harmonics also, I forgot) over time.

Are you actually doing all this this at
paid university time as deputy professor? :)
 
> http://users.ece.gatech.edu/~lanterma/timbresweep_analysis.png
> http://users.ece.gatech.edu/~lanterma/symmetrysweep_analysis.png

More like it yes.
 
>to zero, you only get odd 
>harmonics. 

Thats why it sounds squary or edgy!

>I haven't started to think about yet, but I 
> suppose you could argue that the pulses you see in the harmonic >amplitude
plots look kind of like Bessel functions...

Weeeeeeeeell' its early yet! ;)
 
> This was all done in MATLAB, which is my friend.

"IT" is your friend, a machine, a seducing addictive
robot, a pile of silicon,i have no words! You must be
loneliest professor in the whole lab! :)  
 
> output with a cutoff of around 1.3 kHz... maybe that's there to take some 
> of the "edge" off the sound (and my soundfiles are pretty edgy!)

Throw in a sine instead of the tri wave!

Regards
KD