Andre
Well-known member
Hey everyone,
I've installed rebuilt 325 cards to replace the makeup gain opamp in a Saber console. Two of the output secondaries are used in series and wired directly to the Mains XLRs as a balanced signal. The 325's gain is set accordingly by fixed resistors. The third output secondary feeds the monitor/Ctrl room section of the board through a T-pad attenuator to match the gain of the replaced op-amp.
The modification vastly improved the overall sound of the board, especially by added clarity and focus to the low end. So here's the problem... On both Main output channels I'm seeing an AC voltage (test tone) on pin 2 exactly 3x that of pin 3. So it seems like a simple problem in regards to the transformer wiring. Maybe I need to ground the junction (CT) of the secondaries?? Someone please tell me what's going on.
Thanks.
- Andre
I've installed rebuilt 325 cards to replace the makeup gain opamp in a Saber console. Two of the output secondaries are used in series and wired directly to the Mains XLRs as a balanced signal. The 325's gain is set accordingly by fixed resistors. The third output secondary feeds the monitor/Ctrl room section of the board through a T-pad attenuator to match the gain of the replaced op-amp.
The modification vastly improved the overall sound of the board, especially by added clarity and focus to the low end. So here's the problem... On both Main output channels I'm seeing an AC voltage (test tone) on pin 2 exactly 3x that of pin 3. So it seems like a simple problem in regards to the transformer wiring. Maybe I need to ground the junction (CT) of the secondaries?? Someone please tell me what's going on.
Thanks.
- Andre