Doepfer

Thanks for the exelent service.

--- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@...> wrote:
>
> Dirk,
> 
> it took a while but now we found the reason and a solution ...
> 
> We had problems to understand why the combination of A-110 (rectangle)/A-113
> is working perfect but not A-111(rectangle)/A-113 at low frequencies.
> Strangely enough the combination A-111(sawtooth)/A-113 causes no problems.
> 
> The reason is the negative slope of the A-111 rectangle ! Our oscilloscope
> showed in high res mode (1us/div) that the negative slope is not a single
> slope but has some ups and downs (a bit like a down-going triangle).
> Obviously the waveform converter inside the CEM3340 has this behaviour as
> the rectangle output of the A-111 is nothing but the rectangle output of the
> CEM3340 (only via 1k protection resistor and AC coupling capacitor). In
> normal applications this causes no problems and cannot be heard (each VCA or
> VCF or mixer behind the A-111 smoothes this multiple slopes which are in the
> microsecond range). But the A-113 is very fast and detects these multiple
> slopes at low frequencies. This causes the problems of the A-111/A-113
> combination you described.
> 
> There are several solutions for this problem:
> 
> 1. Do not use the rectangle but e.g. the sawtooth output of the A-111 to
> trigger the A-113 (the sawtooth has no multiple slopes)
> 2. Process the rectangle output by any other module (VCA, VCF, mixer) before
> it is used to trigger the A-113.
> 3. Add a capacitor to the A-113 (in parallel to diode D3). We tried 2n2 and
> then the A-113 tracks perfect from about 10Hz. If you contact me directly
> (hardware@...) I can send you a picture that shows the position of D3
> on the A-113 board. In this case even the rectangle output of the A-111 can
> be used to trigger the A-113.
> 
> Best wishes
> Dieter Doepfer
> 
> > -----Ursprüngliche Nachricht-----
> > Von: Doepfer_a100@yahoogroups.com
> > [mailto:Doepfer_a100@yahoogroups.com]Im Auftrag von vliesgaard
> > Gesendet: Donnerstag, 27. April 2006 12:35
> > An: Doepfer_a100@yahoogroups.com
> > Betreff: [Doepfer_a100] Re: A-113 input sencetivity/tracking problems
> >
> >
> > --- In Doepfer_a100@yahoogroups.com, "Dieter Doepfer" <hardware@>
> > wrote:
> > >
> > > OK, I'll check this with an A-111 and A-113. But it may take a few days
> as
> > > we are very busy with testing and modifying the BBD modules as the
> customers
> > > are waiting anxiously for their modules.
> > >
> > > Best wishes
> > > Dieter Doepfer
> > >
> >
> > Don't worry, you get the full 100 points for customer service. If only
> > other company's were that good.
> >
> >
> > One use the A-113 is creating interesting rhythms.
> > E.g. if you divide the 16th notes of the sequenser, with the A-113, by
> > 2 3 5 and 7 you get a very complex rhythm patern.
> > Thats why it should track low frequenty's.
> >
> > Greetings Dirk
>