Doepfer

hello david,

for such cases i use four internally connected
a138c polarizing mixers. these form a 4x4 polarizing matrix mixer.
the benefit is that i can still use them as separate mixers
if i wish, the drawback is that this solution is a bit big in size
and that the offset function is not working as before.
to make life easier with the "center off" knobs on the a138c,
i use a few jacks and plug them into the unused inputs
to prevent accidental mixing.

best wishes

ingo


--- In Doepfer_a100@yahoogroups.com, David Salter <david.salter@r...> 
wrote:
>
> Thanks Florian for the links, that's basically what I had in mind.
>  
> It would be nice if it could work with both audio and CV and maybe 
with
> centred pots with positive and negative swing.
>  
> I find many occasions when I want to send a signal to multiple
> destinations but with the desire to attenuate on or two of the 
signals.
>  
> Looks like a project for the new year.
>  
> The matrix mixer would be great as I could then use it for combining
> various CV's to make more versatile modulation sources.
>  
> Thanks again
>  
> David
>  
> David Salter
> Senior Project Manager
> Reuters Ltd
> Tel       +44 20 7542 2402
> Mob     +44 7990562402
> email    david.salter@r...
> RM       david.salter.reuters@r...
>  
>  
> 
> ________________________________
> 
> From: Doepfer_a100@yahoogroups.com 
[mailto:Doepfer_a100@yahoogroups.com]
> On Behalf Of Florian Anwander
> Sent: 13 December 2005 16:39
> To: Doepfer_a100@yahoogroups.com
> Subject: Re: [Doepfer_a100] A bit of help needed
> 
> 
> Hi David
> 
> > At it's simplest it's 1 input feeding 4 outputs with level 
controls.
> > Anyone have a simple schematic or suggestions?
> 
> Basically you are looking for something like a simple mixerchannel 
with 
> 4 aux sends. Right?
> 
> Do you want it for audio or for CV? Should it have the possibility 
of 
> send inverted or not?
> 
> 
> In principle you do not need anything else than a frontplate, four 
> 47k-pots (log for audio/lin for CV) plus knobs four 100k-resistors 
and 
> five sockets.
> Connect the input socket to the "upper end" solder pin of all pots.
> Connect the "lower end" solder pin of all pots with ground.
> Connect the center pin of each pot via a 100k-resistor to one output
> socket.
> 
> So far so easy.
> 
> The trouble starts, when you want to mix several of such 
distributed 
> signals in one source (like the Aux-Send-Master in a audiomixer). 
This 
> requires a buffer amp. To avoid this you have to add a buffer-amp 
to the
> 
> each output.
> Example: http://www.doepfer.de/DIY/amp_noninv.gif
> 
> Check out http://www.doepfer.de/DIY/a100_diy.htm and look for the 
matrix
> 
> mixer. Your distribution-module like a matrix mixer, but there is 
only 
> one row of the input section as seen in the 
> http://www.doepfer.de/DIY/matrix_mixer.gif
> 
> 
> 
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