Doepfer

Not sure why you found it relevant to quote the A-110 manual. My post below refers to 
the A-111.

--- In Doepfer_a100@yahoogroups.com, Pieter Volger <volger@...> wrote:
>
> RTFM
> 
> "_Technical remarks:
> _The core of the A-110 is a sawtooth oscillator (in contrast to the 
> A-111-1 <http://www.doepfer.de/a111.htm>, which is based on a triangle 
> oscillator). The other waveforms are derived from the sawtooth by 
> internal waveform converters. As the sawtooth reset (i.e. the 
> back-to-zero slope) is not infinite fast but takes a little bit of time 
> the derived waveforms triangle and sine are not perfect ! At the top of 
> the waveform they have a small glitch or notch that is caused by the 
> sawtooth reset and cannot be eliminated by the waveform converters. The 
> sine is derived from the triangle by a simple diode-based converter and 
> the sine shape is not perfect (only a rounded triangle).
> If a perfect triangle is required the A-111-1 
> <http://www.doepfer.de/a111.htm> is recommended. For a perfect sine the 
> quadrature LFO/VCO A-143-9 <http://www.doepfer.de/a1439.htm> is recommended.
> "
> 
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> laryn91 schrieb:
> >
> > > And we will point out in the module information and user's guide of 
> > A-110
> > > and A-111 that the sine outputs should be called more precisely 
> > "sine-like".
> >
> > Dieter,
> >
> > It's probably just me, but where do you point that out for the A-111? 
> > In my A-111 manual
> > you say just the opposite:
> >
> > "Sine waves are pure waves: they just contain the
> > fundamental, without any harmonics (see Fig. 5).
> > They are thus not suitable for subtractive synthesis
> > (shaping sound with a filter) - as there's nothing to take
> > away!"
> >
> > To the contrary, the A-111 sine is still suitable for subtractive 
> > synthesis. To be accurate,
> > you should say "not suitable for additive synthesis" instead.
> >
> > >If you want a perfect sine you need a VCO
> > > with a sine core.
> >
> > Instead of an impossible "perfect sine", how about just a sine with no 
> > *audible* overtones
> > (<1% THD) like Arp, Moog, Aries, Polyfusion, EML,etc. used to make? 
> > That would now
> > make the A-111 useful for additive synthesis and FM.
> >
> > All you need to do is copy their simple but superior triangle-to-sine 
> > converter design. ;-)
> >
> > --- In Doepfer_a100@yahoogroups.com 
> > <mailto:Doepfer_a100%40yahoogroups.com>, <yahoo@> wrote:
> > >
> > > I will not participate in the emotional discussion about sine waves 
> > but want
> > > to mention some technical details (some of these have been already 
> > mentioned
> > > earlier):
> > >
> > > All standard VCO circuits I know are based on a sawtooth or triangle 
> > core.
> > > When the sine wave is derived from one of these VCO cores you will never
> > > obtain a perfect sine. The antiparallel diodes are the simplest 
> > solution to
> > > derive a sine-like wave from a triangle, the FET circuit is a bit 
> > better but
> > > even far away from beeing perfect. Each kind of waveform converter is a
> > > compromise (except rectangle). If you want a perfect sine you need a VCO
> > > with a sine core. And in return: if you want a perfect triangle you 
> > need a
> > > VCO with a triangle core, if you want a perfect sawtooth ...
> > >
> > > The A-143-9 is the only oscillator in the A-100 that uses a sine core.
> > > Though it was not planned as a VCO but mainly VCLFO it can be 
> > (ab)used as
> > > sine VCO. The main drawback of the A-143-9 is the missing temperature
> > > compensation of the exponential generator. We consider to develop a 
> > sine VCO
> > > based on the A-143-9 circuit but with a temperature compensated 
> > exponential
> > > generator. I expect that the price would be in the Euro 100 range. 
> > We are
> > > also working on a VCO with sine core and linear FM with thru-zero 
> > feature.
> > > But this is another "construction site" because the linear FM and 
> > thru-zero
> > > feature is much more complicated than adding "only" the temperature
> > > compensation.
> > >
> > > And we will point out in the module information and user's guide of 
> > A-110
> > > and A-111 that the sine outputs should be called more precisely 
> > "sine-like".
> > > But even rectangles or triangles are not perfect (each rectangle is 
> > kind of
> > > trapezoid as each rising and falling edge has a slope that depends 
> > on the
> > > inherent slew limiting characteristic of analog circuitry).
> > >
> > > Best wishes
> > > Dieter Doepfer
> > >
> >
> >
>