Soundtracs M series master mod with Neumann 475-2A

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Jitter

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Jan 4, 2014
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Hi guys, I want to make a modification parallel to the master of my Soundtracs M Series mixer. The idea is to be able to add a Neumann 475-2A module to take another master out with the  standard pinout and not with the inverted pinout of years ago.
According to the scheme of the master module, what would be the best point for it?
The ideal should be that the fader master act as resistance "RG" in the module. Would it be correct?

Neumann 475-2A Schematics: http://www.gyraf.dk/schematics/Neu_v475.gif
Neumann 475-2A Manual: http://audio.kubarth.com/rundfunk/getfile.cgi?f=M%2C34R-%238T-%23%3CY-U%5DV%2BVYE%3D6UA%3BFY%3F5C0W-2TR05%5D397%29V%3A6-E36%25N%3D6%25L%2BG%21D%0A%219%40%60%60%0A
I Add the Soundtracs M Series Master Schematic.
 

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Your question is hard to answer because we don't know exacly what you want to do, and the schemo of the master module is difficult to understand since some vital interconnects are missing.
The 475-2A is a complete summing amp + output amp combination. Indeed the summing amp can be used to receive only one input. Do you want to have a separate fadr for this new output? Then you would need to pick-up the signal pre-fader.
Your suggestion to use the fader's own resistance to drive the 475 just doesn't work, for two reasons: first it would shunt the signal going to the original output, second this fader resistance is variable, which would result in inconsistent gain vs. fader travel.
 
I wanna to make a second master out that takes the stereo summed signal before of amp section of the native opamp.
Do you understand my purpose?
 
Stereo, Post fader.
I was thinking and beleive that the best for module is that "RG" will be unit gain 0dB with fixed resistor in 13K.
The problem is...
How do you raise or lower the level with the master fader to the inputs of the module so that the output offers more or less level?
 
Jitter said:
Stereo, Post fader.
Then you take the signal from C39 and C40.

I was thinking and beleive that the best for module is that "RG" will be unit gain 0dB with fixed resistor in 13K.
Maybe. The link to the manual is 404.

The problem is...
How do you raise or lower the level with the master fader to the inputs of the module so that the output offers more or less level?
I don't get it. Do you want to be able to trim the level?
[/quote]
 
In principle I would like to be able to control the output level or volume of the Neumann 475-2A card as if it were with the fader and adi able to control the signal level that enters the DAW.
 
Jitter said:
In principle I would like to be able to control the output level or volume of the Neumann 475-2A card as if it were with the fader and adi able to control the signal level that enters the DAW.
It I understand well, you want a stereo post-fader output with trimmable level.
There are several possibilities:
One is to make Rg variable, the other is to insert a potentiometer or fader between points c and d (top to c, wiper to d, bottom to ground), after having removed the 3 capacitors (0.015, 0.033, 3300p) that you have to remove anyway, since they are part of the 15kHz low-pass filter that was mandatory for FM broadcast.
Have you noticed that you must add the resistors marked Rk on the schemo? I can't tell you more since the manual is not accessible via the earlier link.
 
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