An old message posted to the Csound list.(1999 or thereabouts).
;Some time ago, well actually last year, there was some question about a
;theremin orc/sco.
;I made an attempt to simulate a theremin, but lost it in a disc-crash.
;Here is a recreated version. I made it in Cecilia and modified the orc/sco
;a little, so sorry for the long tables.
;I had a frequency shifter also which used an am-modulated wave instead of the
;stable oscilator, but I haven't recreated it yet.
;Comments anyone?
;
;
;Roger Klaveness
;
;
;Here it comes, beware of wraping !!
;
;--------------------------------------------------------------------------------
;THEREMIN ORCHESTRA
sr = 44100
kr = 4410.0
ksmps = 10
nchnls = 1
gisintab ftgen 0,0,4096,10,1 ;sinwave
gipulltab ftgen 0,0,4096,9,0.5,1,0 ;for pulling distortion, see below
instr 1
;------------------------------------------------------------------------
;Theremin simulation instrument, Roger Klaveness Nov.-1998,
;Converted to Cecilia and back again Jan.-1999
;----------------------------------------------------------------------
;Control parameters
;Originaly generated by Cecilia global instrument
kpitch oscil1i 0,1,p3,1 ; 51 points
kvib oscil1i 0,1,p3,3 ; 101 points
kamp oscil1i 0,1,p3,2 ; 37 points
kvibfreq oscil1i 0,1,p3,4 ; 51 points
;---------------------------------------------
;random amp variation, for shaky hands
kshakeamphand randh 0.1,10
kamp = ampdb(kamp+kshakeamphand)
kvib oscil kvib,kvibfreq,gisintab
;random pitch variation, for shaky hands
kshakepitchhand randh 0.01,10
kpitch = cpsoct(kpitch+kvib+kshakepitchhand)
;-----------------------------------------------------------------------
;Simulation of real theremin
;To oscilators in radiofreq are combined with heterodyning to make
an audible difference wave
;One could use a high samplerate to make it more like the real thing
but that requires
;something like sr=400kHz , and that is probably not necesarry
;the freqspace is divided in 3
;0 - sr/6 : Audio freq we want, Diff-freq from modulation
;sr/6 - 2*sr/6 : Fixed and variable oscilator
;2*sr/6 - 3*sr/6 : Aliased Sum-freq from modulation
;Fixed oscilator sr/3
;Variable oscilator should be in range sr/3 -> sr/3-2000
;freq over sr/6 is filtered out
;---------------------------------------------
;oscilators
a1 oscil 1, sr/3, gisintab ; Fixed oscillator
a2 oscili 1, (sr/3)-kpitch, gisintab ; Variable oscillator
;---------------------------------------------
;pulling distorton
;look at
http://www.paia.com/thereton.htm ;the two oscilators are mutualy influencing the other
;which causes distortion of their waveform
;this effect becomes greater as the freq get lower
;this is just experimentation from my side, and do probably
;not reflects the physics in this process
kpull = ((2000/kpitch)-1)/80 ;more effect at low freq, no eff >
2000Hz = sinwave
kpull = (kpull < 0 ? 0 : kpull)
kpull = (kpull > 0.5 ? 0.5 : kpull) ; not greater than 0.5 pull-factor
ap1shape table abs(a1),gipulltab,1 ; The osc get more affected at
45 degrees, just looked like that in illustration.
ap2shape table abs(a2),gipulltab,1 ; One could experiment with
different phases of gipulltab to get different waveform, or maybe
modulate it also
ap1 = a1+kpull*ap1shape*(a2*0.5+0.5)
ap2 = a2+kpull*ap2shape*(a1*0.5+0.5)
;---------------------------------------------
; Heterodyning = amplitudemodulation
ap1 = (0.5*ap1)+0.5
amix = (ap1*ap2)*kamp
;------------------------------------------------------------------------
;filter out unwanted freq
;10.order butterworth-lp, sr/6
ibgain=0.00001
iagain=-1
aout zfilter2
amix,1,1,10,10,ibgain*.0027,ibgain*.0273,ibgain*.1230,ibgain*.3281,ibgain*.5742,ibgain*.6891,ibgain*.5742,ibgain*.3281,ibgain*.1230,ibgain*.0273,ibgain*.0027,iagain*-7.4907,iagain*25.4989,iagain*-51.8964,iagain*69.8813,iagain*-65.0115,iagain*42.2946,iagain*-18.9909,iagain*5.6301,iagain*-0.9948,iagain*0.0795
;passing frequencies above 25Hz , get away dc
aout butterhp aout, 25
aout balance aout,amix
;------------------------------------------------------------------------
;some tube-overdrive simulation
anorm = aout / 32767
aout = aout - (anorm*anorm*anorm)*10922; some distortion : x-(x^3)/3
;------------------------------------------------------------------------
;output
out aout
;------------------------------------------------------------------------
endin
On Jan 17, 2008 4:03 AM, Jacob Joaquin <
[hidden email]> wrote:
>
> As it would have it, I started to dabble with recreating a theremin waveform
> a few days ago. Haven't gotten too far because of time restraints. I went
> ahead and created a graph of the output from the Big Briar Etherwave with
> various settings. You can download it here:
>
>
http://www.thumbuki.com/images/fullsize/BigBriarEtherwaveWaveforms.gif>
> Hopefully it will help. And I'm personally going to be keeping track of
> this thread as I continue to move forward.
>
> Best,
> Jake
> ----
> The Csound Blog
>
http://www.thumbuki.com/csound/blog/>
>
>
> Mahound wrote:
> >
> > OK... we currently have three theories:
> > - half-sine
> > - sinusoidal through waveshaping distortion
> > - filtered sawtooth
> >
>
> --
> View this message in context:
http://www.nabble.com/Theremin-sound-tp14875977p14887220.html> Sent from the Csound - General mailing list archive at Nabble.com.
>
>
>
>
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