saint gillis
Well-known member
Hi!
I'm putting in a rack 2 Studer 900 channel strips, the complete desk schematics are available here :
ftp://ftp.studer.ch/public/products/Mixing_Analog/900/Manuals/
Here the channel strip detailled schematic :
http://gypsyfarm.free.fr/echange/900_Op_Serv-199.jpg
I ve made a PSU, 2x15V / -24V / -6V, it works quite fine but still few problems :
1) When I'm on the 4 lowest microphone gain positions, I got a hum, notice that for all the other positions it works perfectly!
2) Also notice that when I have selected the "LINE" input, I still have a hum when one of the 4 lowest microphone gain positions is selected (those positions have no effect on the line gain, it only plays on the mic gain, but the hum is still there)
3) When I'm using the "LINE" input and inverting the Microphone "Phase", a big uggly hum appears, when I'm on the "MIC" input position I can invert the phase without a problem...
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The -6V works with a rail called "0V L" "0V DIGITAL", here is the specific Mic Preamp schematic :
Do you think the -6V rail should come from an specific PSU with its own isolated ground?
I'm putting in a rack 2 Studer 900 channel strips, the complete desk schematics are available here :
ftp://ftp.studer.ch/public/products/Mixing_Analog/900/Manuals/
Here the channel strip detailled schematic :
http://gypsyfarm.free.fr/echange/900_Op_Serv-199.jpg
I ve made a PSU, 2x15V / -24V / -6V, it works quite fine but still few problems :
1) When I'm on the 4 lowest microphone gain positions, I got a hum, notice that for all the other positions it works perfectly!
2) Also notice that when I have selected the "LINE" input, I still have a hum when one of the 4 lowest microphone gain positions is selected (those positions have no effect on the line gain, it only plays on the mic gain, but the hum is still there)
3) When I'm using the "LINE" input and inverting the Microphone "Phase", a big uggly hum appears, when I'm on the "MIC" input position I can invert the phase without a problem...
---------
The -6V works with a rail called "0V L" "0V DIGITAL", here is the specific Mic Preamp schematic :
Do you think the -6V rail should come from an specific PSU with its own isolated ground?