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
Message
Sine wave discussion
2008-12-02 by yahoo@doepfer.de
Attachments
- No local attachments were found for this message.