Mixers/Consoles 01V Sub-mixer issues

[chausman]

For one of the shows I'm working on, we are running the band through an 01V, and then into the main board (a Mackie). During sound check, we used the Left main out from the 01V through the snake to a channel on the Mackie, and everything worked. Just as we started the run though, the band mix some weird noise that none of us had heard before. We tried a lot of things, until we switch to the Right main out on the 01V, and the issue went away. What I don't know, is what caused the issue to form, halfway through the day. Phantom power was on for some choir Mics. Is it possible that phantom power killed one of the outputs, and that it may do the same thing later?

 

[bishopthomas]

Can you describe this "weird noise" a bit?

 

[tk2k]

Do you have the capability to plug the O1V directly into an amp/speaker? I assume you've tried a different cable? Are you ground isolated?

 

[chausman]

Can you describe this "weird noise" a bit?

I guess that would be important...

It kind of sounds like an old AT&T phone in the system, but faster. It was a steady pattern though. I'll see if a video would help later.

I know no one had a phone nearby, because all of us with cell phones weren't by anything when it happened.


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[tk2k]

you mean GSM noise? Are you using a balanced cable?
and no it's not possible phantom power killed one of your outs.

 

[chausman]

you mean GSM noise? Are you using a balanced cable?
and no it's not possible phantom power killed one of your outs.

Yes, and yes.

Good, I don't want to loose another one.


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[FMEng]

Phantom power was on for some choir Mics. Is it possible that phantom power killed one of the outputs, and that it may do the same thing later?

Sorry, but I respectfully disagree with Tk2k. Phantom power should not be applied to any line output. They are not designed to have 48 V DC applied to them. I can't say for sure if that's the cause of the noise, but it is very likely and the output stage may be damaged.

Some output stages may tolerate it, depending on whether there are coupling capacitors and if their voltage rating is high enough to withstand it. A coupling capacitor rated for 50 volts or more would be unusual. If the output is DC coupled then it has no protection against phantom power.

This is one reason why the there are TRS line inputs on the Mackie and most other consoles. Get a 1/4" TRS and a female XLR and make yourself an adapter.

 

[tk2k]

Sorry, but I respectfully disagree with Tk2k. Phantom power should not be applied to any line output. They are not designed to have 48 V DC applied to them. I can't say for sure if that's the cause of the noise, but it is very likely and the output stage may be damaged.

You're right, my statement was too general. In this case I do not believe it is possible because most yamaha digital boards are capable of dealing with it, at least that's what a rep told me. Still said it wasn't an ideal situation but also said it shouldn't kill anything.

 

[FMEng]

The pinout for an adapter:

XLR pin 1 to phone plug sleeve
XLR pin 2 to phone plug tip
XLR pin 3 to phone plug ring