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Re: AW: AW: [Doepfer_a100] A-111-2 question

2016-09-14 by Neil Kagan

Ah I see thanks Dieter; it took a few reads but I think I understand!

Regards,

Neil

Sent from my iPhone

> On 12 Sep 2016, at 13:42, yahoo@doepfer.de [Doepfer_a100] <Doepfer_a100@yahoogroups.com> wrote:
> 
> The drop to zero is not the important thing (except for LFO applications
> where the modulation can stop and continue again when the linear control is
> turned up again). But the linear frequency bias/offset is important because
> the linear FM is different when the bias/offset gets lower. Usually VCOs
> even with a linear FM input have no linear frequency control. The internal
> circuit of the VCO multiplies the shares of the linear and exponential
> section to define the VCO frequency. Without the manual linear frequency
> control the linear share (without linear FM) has a fixed value which is
> typically near at it's maximum. A linear FM with e.g. 1 Vpp applied to the
> circuit is totally different compared to a situation with e.g. half the
> linear frequency bias/offset. With the LF control you are able to control
> the linear FM much better than without this feature. The standard VCO
> situation of the A-111-2 is with LF control fully CW (i.e. the linear share
> near to maximum).
> 
> Best wishes
> Dieter Doepfer
> 
> 
>> -----Ursprüngliche Nachricht-----
>> Von: Doepfer_a100@yahoogroups.com [mailto:Doepfer_a100@yahoogroups.com]
>> Gesendet: Donnerstag, 8. September 2016 22:00
>> An: Doepfer_a100@yahoogroups.com
>> Betreff: Re: AW: [Doepfer_a100] A-111-2 question
>> 
>> 
>> 
>> 
>> 
>> Thanks Dieter,
>> 
>> 
>> Can I ask what the application of a manual drop to zero is?
>> 
>> 
>> Neil
>> 
>> Sent from my iPhone
>> 
>> On 8 Sep 2016, at 18:56, yahoo@doepfer.de [Doepfer_a100]
>> <Doepfer_a100@yahoogroups.com> wrote:
>> 
>> 
>> 
>> The A-111-2 has no thru-zero feature but only a manual control and a CV
>> input for linear frequency adjustment/modulation. With all controls at
>> minimum the oscillation nearly stops (typ. 1Hz in VCO mode). But we are
>> working on a thru zero version of the A-111-2 (probably named
>> A-111-4). But
>> it's too early to publish any details as the circuit is a bit more
>> complicated. It's based on a suggestion by Doug Curtis in his documents we
>> obtained while we were the European distributor for the Curtis
>> chips in the
>> the eighties. The circuit is similar to the CEM3340 based thru zero VCO by
>> Juergen Haible but with a few more features (like zero point modulation).
>> 
>> Best wishes
>> Dieter Doepfer
>> 
>>> Hi people,
>>> 
>>> Does anyone know if the new VCO has thru zero capability? It
>>> looks like it from the LF control being able to go to 0 but there
>>> isn't specify mention.
>>> 
>>> Neil
> 
> 
> 
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