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Author Topic: Y-ing a signal into a mixer with Phantom power already on it.  (Read 4970 times)

Steve M Smith

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Re: Y-ing a signal into a mixer with Phantom power already on it.
« Reply #10 on: January 23, 2016, 04:16:29 am »

This is the exact same setup as a monitor console applying phantom power to a passive split, and the FOH console is seeing the 48V.   It happens 1000's of times a day, and is perfectly fine.

Yes - If an input can stand having 48v phantom applied internally, it can stand it when applied externally from another mixer.

There are a lot of phantom power myths out there.  I saw a hilarious one a couple of days ago.  It was a forum post about removing the transformer from an SM57.  Someone warned against the 'danger' of running it with phantom power on "unless you know for sure that your 6K8 resistors are 1% precision types so both pins see the same voltage".

1.  No current can possibly flow from +48v to +48v so no damage can occur.
2.  Even if current did flow, the resistors limit it to a level which could not burn out the winding of a dynamic mic.
3.  Without a current flow there XLR inputs are all generally fine with having phantom applied by an external source, but the same cannot be said about 1/4" inputs. is no voltage drop across the resistors so their precision is irrelevant,

This was almost as funny as the phantom power with ribbon microphones mythology.


Steve.
« Last Edit: January 23, 2016, 04:23:00 am by Steve M Smith »
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James Rowe

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Re: Y-ing a signal into a mixer with Phantom power already on it.
« Reply #11 on: January 23, 2016, 05:51:48 am »

I blew up a mixwiz a few years ago plugging it's main out into a phantom powered XLR on another mixer. Up until then I would have agreed with you!
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Steve M Smith

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Re: Y-ing a signal into a mixer with Phantom power already on it.
« Reply #12 on: January 23, 2016, 06:40:14 am »

I blew up a mixwiz a few years ago plugging it's main out into a phantom powered XLR on another mixer. Up until then I would have agreed with you!


I didn't say anything about outputs, I was referring to parallel inputs - which is standard practice.


However, I would be very surprised if a MixWizard output couldn't stand having phantom power applied.


Steve.
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James Rowe

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Re: Y-ing a signal into a mixer with Phantom power already on it.
« Reply #13 on: January 23, 2016, 06:53:21 am »


I didn't say anything about outputs, I was referring to parallel inputs - which is standard practice.


However, I would be very surprised if a MixWizard output couldn't stand having phantom power applied.


Steve.

Tell that to my repair guy. The mixer still lit up but no sound. A couple of burnt out resistors inside.
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gordonmcgregor

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Re: Y-ing a signal into a mixer with Phantom power already on it.
« Reply #14 on: January 24, 2016, 06:40:37 am »

Tell that to my repair guy. The mixer still lit up but no sound. A couple of burnt out resistors inside.
Steve you'd be suprised how easily Phantom can kill an output on modern electronically balanced kit these days, ask anyone who has had the misfortune to have a vidiot leave phantom switched on on his camera when you send him a feed
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Keith Broughton

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Re: Y-ing a signal into a mixer with Phantom power already on it.
« Reply #15 on: January 24, 2016, 06:53:21 am »

Not knowing what USB interface you are using, this might not be applicable.
My Behringer 404 has global phantom but the XLR inputs are combo type with TRS as well.
I feed the return noise to the TRS inputs as they don't have phantom power on them.
As for the transformer iso, correct me if I am wrong but would a transformer (on just the one side of the Y)not create phase shift to the reference input?
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Rob Spence

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Re: Y-ing a signal into a mixer with Phantom power already on it.
« Reply #16 on: February 13, 2016, 12:03:55 pm »

Steve you'd be suprised how easily Phantom can kill an output on modern electronically balanced kit these days, ask anyone who has had the misfortune to have a vidiot leave phantom switched on on his camera when you send him a feed

I use iso any time I feed someone else.


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Scott Holtzman

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Re: Y-ing a signal into a mixer with Phantom power already on it.
« Reply #17 on: February 13, 2016, 10:15:54 pm »

Not knowing what USB interface you are using, this might not be applicable.
My Behringer 404 has global phantom but the XLR inputs are combo type with TRS as well.
I feed the return noise to the TRS inputs as they don't have phantom power on them.
As for the transformer iso, correct me if I am wrong but would a transformer (on just the one side of the Y)not create phase shift to the reference input?

A capacitor in series will block DC.
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Scott AKA "Skyking" Holtzman

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Re: Y-ing a signal into a mixer with Phantom power already on it.
« Reply #17 on: February 13, 2016, 10:15:54 pm »


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