[sdiy] coupler module

[jhaible at debitel.net]

I have 2 Stereo inputs and 2 Stereo outputs on my JH-3, and
this has prroved very useful over the years. Usually
one output is for the modular as a synth, and the second output
is for the modular as a processing device.

Level adjustment of inputs and outputs (4 stereo pots)

Overload indicator for the inputs

Two switches (4p2t) to bypass input 1 to output 1
and input 2 to output 2 (Important!)

Stereo outputs are normalised such that a single
plug in one channel (right) will feed both left and
right outputs. So you can simply plug a mono synth
output in there, or use a VCPan or 2 VCAs for stereo
operation.

Inputs: Derive a mono (sum) signal from each of the
stereo input pairs. You rarely feed a stereo signal
into two identical modules for true stereo processing ...
But you often want to feed a stereo synth into
the modular, process it in mono, then make it
stereo again (panner, phaser, whatever). And you
want to bypass this mono->stereo processing path
to your original stereo->stereo path when processing
is turned off (thus the 4p2t switches)

Tone controls: Nice of a (quite limited) VCS3,
but not really needed on a big modular with
several filters, IMO.

JH.


> Every synth needs a coupling module to the tape machine or mixing desk.
> 
> I plan to build some soon, containing:
> 
> -4 balanced inputs, 2 balanced outputs (trafo or electronic)
> -2 or 4 (several) unbalanced inputs (for other synths)
> -input or output scaling circuits (the analog synth can have +-13V or
> +-100mV
>  as extremes), the usual levels are -10dBu = 0.245 V RMS ~ 0.35V peak
>                                  or   6dBu = 1.55  V RMS ~ 2.2 V peak 
> 
>  assuming that 0 dBu = 0.775V RMS and sine wave form.
>  So gains of 37,    0.29,  5.9 , 0.045
>           or 0.027, 3.4,   0.17, 22    (reciprocal)
>  can be needed, so a range of 37 to 0.027 seems to appear.
>  This is no problem since resistor networks can be changed
>  if necessary. Plug in connections of resistors on the PCB
>  seems to be a good idea.
> 
> -A good question is if any EQ is needed. Shelving bass and treble
>  and perhaps some mid bell shaped EQ.
> 
>  I'm not sure if this needed. It could save a mixing desk.
> 
> -Another question is if any external effects send/return is needed
> -Certainly a level meter plus overload indicator with hold/reset
>  is needed for the line out.
> 
> If all features are build, I end up with a little mixing desk.
> That is certainly too much. 
> 
> So what is your practical experience?
> What is needed?
> 
> Martin Czech
> 
>  
> 
> 
> 




-------------------------------------------------
debitel.net Webmail