C24- Phantom Power causes crackle and pops

[GreenDC]

Hi all, I'm having issues with my Control 24 interface- I get incessant crackles on several channels of the first bank of preamps when phantom power is engaged. When it is turned off, the signal is clean as a whistle. Even when there is no cable plugged into the input of the problem preamps, if the preamp is turned to mic, there's crackle. Another strange issue is that if I have an external preamp in the signal chain before the preamp on the C24, there is no crackle (via a patchbay). Any idea whats up with this? The second bank of 9-16 is fine, and this seems to manifest every summer, when it is more humid, and here in DC it gets super humid. Thanks

[conrad787]

Hello GreenDC,

I too live in the DC area (Bethesda, MD - www.blueroommusicstudio.com)

I don't have crackles with phantom power, but some WEIRD issues with phantom instead. For some reason, mic input #3 will NOT send phantom power out to a condenser mic. If I plug a dynamic into #3 it sounds great, and if I plug a condenser into 1, 2, or 4-8, it sounds great as well. Does anyone know why the C24 would decide not to send phantom out certain channels?

Thanks,
Conrad
Blue Room Productions

[otlyer]

Am in dc too

[albee1952]

Some ideas to consider:
For GreenDC, external preamps should come in via LINE inputs(which don't have phantom power). Maybe check your snakes(try swapping the 1-8 snake with the 9-16 snake and see if the problem moves).

For conrad787, check the snake and I bet you find a bad ground/pin 1 on your #3 line. A dynamic mic will work fine without pin 1, but phantom power needs pin 1 to complete the power connection(pin 1 carries the minus side of phantom DC voltage)

[Fullsound Recording]

Or a bad rail feed in general at PSU - PSu connector- or jacks mount to PCB? Maybe oscillating Dc at PSU?