will plugging/un-plugging mic with 48v on blow out protection diodes over time?

[Les C.]

I just noticed a thread for my Fireface 400 audio interface that indicated that over time, plugging and un-plugging a microphone while 48v phantom is enabled will blow out the protection diodes (they suggested turning 48v off before plug/un-plug).

And ... it made me wonder whether this would also be the case for the RED's XLR inputs?

 

[Mike P.]

What XLR inputs?

If you're talking about the 3.5>adapter>XLR with phantom power on, I've read on these forums that unplugging the 3.5mm while they're hot (with phantom power on) will cause damage. Actually, I think whoever it was said that you shouldn't connect/disconnect the 3.5mm jacks while the camera is on at all (phantom or no phantom). Something about the male 3.5 jack shorting out the tip/sleeve/ring of the input as it's being inserted.

I know; Anecdotal at best... So, yeah, I'd like confirmation on this as well...

 

[Les C.]

No, I'm talking about plugging in/out an XLR into an A-Box or other adapter.

If my FireFace 400 has protective diodes, I'd expect that the RED does also.

Rather than wonder, I'm not going to plug/un-plug from the XLR while the camera is on, as I'm sure it would not be inexpensive to fix.

 

[Mike P.]

Yeah that's the same difference (as per, plugging into "the camera's XLRs" that are attached to the camera's 3.5mm jacks via an adapter.)

I've also been avoiding plugging/unplugging while operational. The only reason unplugging at the XLR jack *might* not cause things to blow is because the XLR jack won't short out its prongs against one another whereas, when inserting the 3.5mm jack, it literally rubs across all three tip/ring/sleeve "terminals" as it's being inserted (which is when the short would happen.) I also think that if they blew that easily, we'd probably hear about it often from people who rent their cameras... That said, better to be safe than sorry... (until I get official word from RED, that is.)

 

[Dave Blackham]

Pluging unpluging a connector with phantom volts on it should not damage it any unit. Phantom volts are usually fed via a resistor in most audio kit to prevent any damage incase of a short. Id be pleased to hear from Red on this though.

Its best not to do introduce a short in the first place if it can be avoided. Im not a fan of the 3.5mm jacks which is not a good connector for audio particularly with 48V phantom.

 

[Les C.]

I'm not sure it's a short that's the problem.

The FireFace is a $1K+ pro audio interface, and they have noticed this issue over time, where there's more noise if phantom power is turned on than when it is off.

They said (their native language is German) "Every time you unplug and plug a mic 48V should be switched off first. Or sooner or later the protection diodes will die themselve."

So, this might degrade the sound in a RED over time if the diodes become damaged? Or maybe not, but ... I bet all devices that provide 48v have the protection diodes and that they can fail over time due to stress.

Anyway, it was news to me that this was possible, so ... just thought I'd post so others can err on the side of extreme caution.

 

[Dave Blackham]

Well its news to me. Ive worked in Audio for over 30 years and not heard of this issue or ever had +48 fall over. Id hope its just Fireface then.

 

[Steve Sherrick]

It was suggested to me a long time ago that whenever connecting devices that rely on phantom power to turn off the phantom power and give it a few seconds before disconnecting. And to not connect microphones to a hot phantom power input.

Honestly, I think this is precautionary procedure and that 99% of the time you won't damage a mic when you do it wrong. The bigger risk is probably in connecting the mic while phantom power is hot, I suppose there's a risk there of damaging certain components in the mic. I generally follow the procedures that were shown to me but in the back of my mind I know I'm probably ok if I forget.