A multi-purpose PCB: Mic preamps, summing amps, line channels, mixer..?

[Dr_J]

Any news on that?

I'm thinking of a line mixer... ?!

ROCK-ON

 

[ramshackles]

The very first module is almost ready:
http://groupdiy.com/index.php?topic=55189.20

It's an EQ...

The connector pinout/backplane has been designed and the first backplane PCB's are on the way...

The thinking now is not for a single 'do-all' PCB as it makes the amount of handwiring much more and hence the build less simple.
But, I would like to be able to offer something where you could get a simple mixer up and going with a very small number of modules and then have the ability to add preamps/eq's etc if desired...

At the moment, I have 1 eurocard which provides a line receiver & gain, fader and some auxes, and another eurocard which gives you a passive panpot and group-select.

The idea is to be very simple (something like 'The Box' or other 'desktop' mixers) and provide a choice of discrete or IC amps...

4 mono aux buses (but only 3 available on a single eurocard - aux 3/4 is selected via a switch. Saves a pot and knob and crucially real estate).

4 stereo mix buses (including the master).

So the absolute simplest mixer would be 2 modules on each channel (input module and switching module) and 4 summing cards...

 

[gar381]

I updated the PCB connector layout to reflect the changes suggested here: 0V for the 5V connection, 58V and 48V GND.

I have not managed to find Jensen or Cinemag transformers which have the same footprint for both a 1:2 (or 3) mic transformer and a 1:1 line transformer...

Hi ramshackles

Just ran across this thread..  VERY NICE IDEA !!

Please double check your V- and output pins on your DOA sockets.
(I think you may have them flipped .)

All the best with this project!!

GARY

 

[ramshackles]

You are right - the first prototype I did of that design I had to install all the DOA's upside down :S...

I am now thinking that a single 'do-all' PCB is too complex and prone to mistakes, but a simple line-level mixer, with auxes and groups could be made with just 3 different module types.

You could then expand it to something more complex by adding your EQ's/Preamps/Compressors/whatever...

The first 4 in this table would be the 'base modules'

Module	Concept	Design	Prototyping	Docs	On sale
Backplane	x​	x​	o​
Receiving	x​	o​
Routing	x​	x​
Summing	x​	o​
Monitoring	x​
Easy69 (EQ)	x​	x​	x​	o​
ISAish	x​	o​
S**tec-ish	x​	o​
Eurocard PS	x​	x​	o​
External PS	o​

 
   
   
   
   
   
   
 
 
   
             
 
   
         
 
   
         
 
   
         
 
   
     
 
   
                 
 
   
         
 
   
         
 
   
             
 
   
     

The summing PCB would be the most like a 'do-all' PCB as it would incorporate stereo/mono and probably balanced/unbalanced summing depending on how you put it together. Wiring it as a preamp wouldn't be too hard either, although I dont think I will document it. The summing PCB is based off that initial design you've quoted...