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Author Topic: Discoveries about the original CS-80 ( a reminder for devs )  (Read 3578 times)


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Discoveries about the original CS-80 ( a reminder for devs )
« on: December 05, 2005, 10:18:51 am »
Hi all
You all know how am I devoted to the cause of Yamaha CS80 and therefore to its V version which I won't ever stop to praise Arturia for.
With the help of the guys at Arturia CS-80 Yahoo! Group ( http://groups.yahoo.com/group/arturiacs-80v ) and from some guys at Yamaha CS-80 Yahoo! Group I was able to determine some exact values and datas about many detailed things into the CS-80 :

Waveforms : version 1.5 has corrected the sawtooth but still sawtooth and the square wave needs attention. It is not a completely irregular square wave but it has a strong presence of bass frequencies

The most amazing discovery about the pure waveforms is that they change their shape at low or very low frequencies. By some experiments I made with analyzers it seems that under 100 Hz and without the help of the filters there is a sensible and proportional loss in higher harmonics (lower is the pitch, lesser are the harmonics ). This is common to both the sawtooth and the square . I think this is one of the fundamental "nuances" that make the CS80 different from any other synthesizer out there.
I found that even the sine wave used in modulation oscillators (PWM, SubOSc, Ringmodulator, Chorus modulator) is very interesting : it isn't a plain sine , because it has one single harmonic in it that enriches the sound , especially within the ringmodulator.

Other discoveries (and therefore updates to schedule ) concern the chorus module : aside from changing the modulator wave it has a built in feedback circuit that provides the famous phase shift ; from my experiments it should feature an amount around 42% of the original signal ( from out1 to in1+2 ) and a given distortion of 2.5%. There is also a "leslie brake effect" aka a change in the speed when switching from Ch to Trem and backwards

RM: on the V it is way too extended : it features a mid freq speed ( no more than 2500 Hz and with DEPTH at full) and the envelopes are much shorter than on the V. There is also a hidden release stage which lasts 250ms

InitialPB: same 250ms one stage envelope with rounded ( linear curve ).
More to come.


a CS-80Vist


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