Doepfer

Great post Dieter, and for the record I love that my A-143-9 doesn't have
temperature compensation. It makes for very organic changes over long
periods.

On Tue, Dec 2, 2008 at 5:26 AM, <yahoo@doepfer.de> 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
>
>  
>


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