Doepfer

the A111 IS useful for linear FM as it is now.
i am using my A111's for linear FM for 8 years now...


Bakis Sirros - Parallel Worlds / Interconnected / Memory Geist
[Doepfer_a100] group owner
www. parallel - worlds - music. com
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www. DiN. org. uk
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Athens - Greece

--- On Tue, 12/2/08, laryn91 <caymus91@mac.com> wrote:

From: laryn91 <caymus91@mac.com>
Subject: [Doepfer_a100] Re: Sine wave discussion
To: Doepfer_a100@yahoogroups.com
Date: Tuesday, December 2, 2008, 6:19 PM






> 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, <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
>

 














      

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