Can Axe FX 3 output 1 XLR tolerate phantom power

J

John Michael

New Member
Can I plug output 1 XLR into a mixer that has global phantom power feeding all the XLR lines? In our rehearsal studio, our new mixer has a global phantom power switch that we need to keep on to power the drum mics. The manual states that the phantom power feeds all the XLR lines. I usually run my AXE FX 3 directly into the XKR input. Will this damage my AXE FX? I just don't want to have to run an XLR-to-1/4" cable as it just doesn't have the same quality sound. Please advise.
 
John Michael said:
Can I plug output 1 XLR into a mixer that has global phantom power feeding all the XLR lines? In our rehearsal studio, our new mixer has a global phantom power switch that we need to keep on to power the drum mics. The manual states that the phantom power feeds all the XLR lines. I usually run my AXE FX 3 directly into the XKR input. Will this damage my AXE FX? I just don't want to have to run an XLR-to-1/4" cable as it just doesn't have the same quality sound. Please advise.
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Interesting fact when the Helix was first released connecting it to phantom power caused the unit to emit loud white noise.
I know this first hand.
Almost ruined a gig…..
 
If the output on the Axe FX III is wired in the same way as it was on the II XL, you should make sure that there's nothing plugged into the 1/4" jacks at the same time. I fried some resistors and a few of the tubes in a poweramp once by connecting an cable with phantom power to Out1 XLR while the poweramp was plugged into Out1 1/4". Seems like the outputs are electrically linked and the tube amp did not tolerate phantom power.

@FractalAudio does this still apply to the III?
 
l4mpi said:
If the output on the Axe FX III is wired in the same way as it was on the II XL, you should make sure that there's nothing plugged into the 1/4" jacks at the same time. I fried some resistors and a few of the tubes in a poweramp once by connecting an cable with phantom power to Out1 XLR while the poweramp was plugged into Out1 1/4". Seems like the outputs are electrically linked and the tube amp did not tolerate phantom power.

@FractalAudio does this still apply to the III?
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It doesn't apply to the III and doesn't apply to the II XL. Both products feature fully electrically isolated XLR and 1/4" outputs.
 
FractalAudio said:
It doesn't apply to the III and doesn't apply to the II XL. Both products feature fully electrically isolated XLR and 1/4" outputs.
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That's curious. I might misremember the exact output wiring as this happened 4-5 years ago, but fact is I played the II XL through my Engl 2x35W into my cab, and while I was playing my drummer connected an XLR cable with phantom power to the II XL which caused a "pop" and the power amp was dead with an ~150€ repair bill. If the outputs are isolated, how could that happen?
 
l4mpi said:
That's curious. I might misremember the exact output wiring as this happened 4-5 years ago, but fact is I played the II XL through my Engl 2x35W into my cab, and while I was playing my drummer connected an XLR cable with phantom power to the II XL which caused a "pop" and the power amp was dead with an ~150€ repair bill. If the outputs are isolated, how could that happen?
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I don't know but you should never connect or disconnect an XLR cable with live phantom power.
 
FractalAudio said:
I don't know but you should never connect or disconnect an XLR cable with live phantom power.
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Yeah, I would usually make sure phantom power is off (and stays off) when connecting the Axe to the interface, but the drummer forgot to check. Be assured he was thoroughly reprimanded for that ;)
No doubt that it was a user error, I just thought to bring it up to spare others a potentially expensive mistake. But it seems that was unneccessary as it shouldn't be a concern anyways. Maybe in my case it was a different wiring issue - we were on a band vacation in a rented house and had everything set up in the living room with a lot of extension cables, so not exactly the cleanest of setups.
 
I don't think the following is necessarily true.
Chances are that a mixer with phantom power will also have some balanced 1/4" ins. Try one of those with an XLR to TRS cable. If this eliminates a trip through your XLR channel's mic pre, it may in fact sound better that way.

I just don't want to have to run an XLR-to-1/4" cable as it just doesn't have the same quality sound.
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l4mpi said:
Yeah, I would usually make sure phantom power is off (and stays off) when connecting the Axe to the interface, but the drummer forgot to check. Be assured he was thoroughly reprimanded for that ;)
No doubt that it was a user error, I just thought to bring it up to spare others a potentially expensive mistake. But it seems that was unneccessary as it shouldn't be a concern anyways. Maybe in my case it was a different wiring issue - we were on a band vacation in a rented house and had everything set up in the living room with a lot of extension cables, so not exactly the cleanest of setups.
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That's why we can't have nice things when drummers are around...
 
FractalAudio said:
I don't know but you should never connect or disconnect an XLR cable with live phantom power.
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I was just looking for the answer the OP had which is answered here but this made me wonder, how bad is it to turn the phantom power switch on the mixer on or off when the Axe is already connected and turned on? No effect?

I've never done it but... I could see myself doing it. :oops:
 
Find a proper way to get balanced signals into the mixer without phantom power: Whether its XLR to TRS cables to Line IN, or using only dynamic mics, or a +48v isolation phantom power box for powered mics (so the mixer +48v can be off). Eventually, somebody is going to plug a ribbon mic, a synth pedal, or something unisolated into a +48v powered on mixer pre and fry it; even by just shorting it out when plugging in. Even though the Axe will be OK, many other audio devices won't. Its a problem waiting to happen to something. Fix it. The sooner the better. And in the future, I recommend a mixer that has phantom power assignable on a per channel, or at least per bank basis.
 
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^^This. That new mixer is a ticking time bomb. Hopefully, you can just return it. Failing that, use it it exclusively to power the drum mics and put tape over the other ports so no one else plugs in.

But, to answer your orignal two questions. Yes, you can plug in out 1, and no it will not damage your Axe.
 
Brand new Axe III user here, just to get as straight forward and stupid-proof of an answer (I'm the stupid). Can you send 48v phantom power to each OUT1 XLR (L+R) WITHOUT any chance of damaging the AXE III?
 
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