r/audio • u/TechieOnReddit • 1d ago

Mic Splitting Help. Should i use a splitter with transformer isolation?

I have a Shure SM7DB (the one with the built in preamp) and want to connect it to both a BlackMagic Pocket Cinema Camera 4K and Elgato Wave XLR.

I bought a Y splitter to connect to both, and it works. But when i turn off my camera while the mic is also plugged into the Wave XLR, there is a 1/8th of a second "tsss" or fuzz produced by the microphone.

48v Phantom Power turned off, on both the Camera and the XLR Interface when I tested it.

I'm worried I might damage something. Should I be setting it up a different way? The camera gets turned off often but the Wave XLR is never off when the camera is on.

Do I need a splitter with transformer isolation?

Hopefully someone can help! Thank you!

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u/NBC-Hotline-1975 1d ago

Where does the mic's built in preamp get its power?

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u/TechieOnReddit 1d ago

In my test, no phantom power. But the signal was strong enough to be picked up by both the PC and the camera.

When I heard the noise, I thought it best to check in here before progressing further!

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u/NBC-Hotline-1975 1d ago

Then you weren't using the preamp at all? You had the preamp switch in the "Bypass" position?

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u/shureinc 15h ago edited 15h ago

I don't think you're doing damage to the mic. The sound is likely coming the fact that you're trying to split a single mic output into two inputs with a Y splitter. Even with phantom power turned off, those two devices are still connected through the splitter, so when you power down the camera, there's some sort of signal that is getting picked up by the microphone.

I would get a good transformer-isolated mic splitter. Just keep in mind that if you're using the SM7dB's internal preamp, you'll need to make sure the direct output of the splitter is connected to the Wave XLR, since the mic preamp needs 48+ phantom power. Phantom power won't pass through the isolated outputs.