Patch bays/XLR and Phantom Power

Axe_meister · January 2023

Looking to tidy up my home studio setup (cables everywhere) and am looking at patchbays.
Now normal TRS/TS cables without phantom power are obviously not an issue, but what about XLRs with Phantom power?
Currently my condensor mic is plugged straight into an interface. I have two interfaces one for work attached to my laptop and one for home attached to my PC. These interfaces provide the 48v phantom power.
From what I have read it is not a good idea to have Phantom power going through a patch bay?
So what is the solution? The only one I can think of is have my microphone going through some sort of Mic Pre-amp with the output going to the patch bay. Whilst this is a workable solution for a single microphone, what if I add a second microphone, I'd need another pre-amp.
Can you get some sort of XLR input rack unit that passes through 48v for the microphones with a 1/4 jacks out at the back without the phantom power? These would then be routed through to the back of the patchbay?

Stuckfast · January 2023

You could get a stand-alone phantom power supply and keep it 'downstream' of the patchbay. There are lots of small single-channel ones around, and if you look on eBay etc you should be able to find a larger multi-channel one fairly affordably. AKG used to make an eight-way one that pops up from time to time for example.

paganskins · January 2023

Would XLR to TRS going into the patch bay and TRS to XLR out not carry the phantom power? Assuming it was set to thru/open.

I was hoping to do this with the XLR input of my Helix Rack.

Stuckfast · January 2023

Yes it would carry the phantom power and that's exactly the problem. If you plug in something that can't tolerate phantom power you risk damaging it. That's especially the case with TRS plugs as you get a momentary short when plugging or unplugging the cable.

paganskins · January 2023

Stuckfast said:

Yes it would carry the phantom power and that's exactly the problem. If you plug in something that can't tolerate phantom power you risk damaging it. That's especially the case with TRS plugs as you get a momentary short when plugging or unplugging the cable.

That's useful to know @Stuckfast, I wasn't planning on using the phantom power option but if the need arises in the future I'll know not to run it that way.

Am I OK doing the above without phantom though?

octatonic · January 2023

I do not put microphones on TRS or bantam patchbays.
It doesn't matter how careful you are, eventually something will get fried.
Ask me how I know.

So, XLR patchbay for microphone inputs, bantam bays for everything else.

Sporky · January 2023

octatonic said:
Ask me how I know.

How do you know?

goldtop · January 2023

Stuckfast said:

Yes it would carry the phantom power and that's exactly the problem. If you plug in something that can't tolerate phantom power you risk damaging it. That's especially the case with TRS plugs as you get a momentary short when plugging or unplugging the cable.

I think that explains why quite a few Akai Forces have had their audio I/O boards fried.

octatonic · January 2023

Sporky said:

octatonic said:
Ask me how I know.

How do you know?

I forget.

Danny1969 · January 2023

You can switch balanced mic signals just like any other signal using switches. This box I built switches 2 mics into the same live channel but you can switch 1 mic to 2 different interfaces using the same trick.

Image: https://www.thesuperheroesonline.co.uk/micboxswitch.jpeg

You can do it with one 3PDT ... that box has 2 switches for a mute all option as well

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Patch bays/XLR and Phantom Power

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