Bad Hum from XLR Output 1

MKeditor

MKeditor

Experienced
My new magic box had it's maiden voyage this past weekend. It debuted at my mega-church gig. Best environment I play in. Three thousand seat venue with state of the art PA and (EAW) monitors. I had the sound team mute the inputs of my two channels since the new Axe-FX II has a pop when powered on. As soon as they brought up the faders at FOH, a bad hum was heard. My Ultra did that but once the ground lift button would be engaged it would remedy the problem. Not the case this time. The hum went from really bad to just bad. It was better but not acceptable. We ended up having to run 1/4 from Output 1 to two Countryman DI boxes. That did the trick. Of course that is not what I want to happen. Has anyone else experienced this? Is there a cure other than investing in direct boxes? I read in the manual about the humbuster cables but that won't help the XLR outputs.

On a brighter note, once the DI's were in place, the tone was lovely. It was great hearing it through FOH rumbling through the room. The engineer loves how great the black box sounds and (usually) with no fuss. The other guitar player was using an AC30. The engineer said that that amp sounded like it was in another room. He said with some expensive mics and plenty of time to adjust he could make the AC30 sound great but they rarely have the time.

Anyway.....suggestions?
 
I assume you tried other cables. Was phantom power on, on the board channel? Might be some wiring bad with the xlrs out on the axe-fx. There are only a few part differences between the XLR output 1 and the quarter inch.
 
Don't know about if Phantom power was on. The cables were used from DI's so that rules that out.
 
I was just told that one of the channels had phantom power running. Could that have been the issue?
 
MKeditor said:
I was just told that one of the channels had phantom power running. Could that have been the issue?
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I've had issues with hum and phantom power with some gear. I haven't tried putting phantom power w/ the IIs output, but my guess is that may have been the problem.
 
I just got the Axe II and have been using it in my live room with a Les Paul.

Just last night I started to get what sounds like single coil hum... it goes away depending on my orientation in the room just like a single coil guitar would.

I've never had that problem with this guitar before. I haven't had time to debug it yet (my wife has a baby due any day now:) ) but thought I would mention it.

I'm guessing my issue is not the Axe II but I never had the problem with my Ultra using the same guitar, guitar cable, XLR patch cables to the mixer, same mixing desk etc.

Richard
 
barhrecords said:
I just got the Axe II and have been using it in my live room with a Les Paul.

Just last night I started to get what sounds like single coil hum... it goes away depending on my orientation in the room just like a single coil guitar would.

I've never had that problem with this guitar before. I haven't had time to debug it yet (my wife has a baby due any day now:) ) but thought I would mention it.

I'm guessing my issue is not the Axe II but I never had the problem with my Ultra using the same guitar, guitar cable, XLR patch cables to the mixer, same mixing desk etc.

Richard
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sounds like your issues is environmental. computer monitors or lights possibly.
 
Different venue yet same bad hum from XLRs requiring direct boxes to be usable. I will run some tests tomorrow. This situation needs resolving.
 
I plugged my FBTs into the XLR and jacks and it sounds fine. This is frustrating. I have played both of those venues many times with my Ultra with no problem. Now the Axe II hums big time but I am not able to replicate it at home. It is hard to know how to deal with this situation.
 
There may be a short to chassis somewhere in the unit. Measure from pin 1 of each XLR to chassis with an ohm-meter. With the ground lift switch in one position you should read almost zero, in the other position you should read very high. If not, then there is a short somewhere.
 
Did the hum go away in the venue(s) when you disconnected from the FOH feed and just had the FBTs connected? I'd sort of assume it would if putting DI boxes on the FOH outs killed the hum. Sounds like a classic ground loop to me. DI boxes act as isolators as well as converting unbalanced to balanced.
 
FractalAudio said:
There may be a short to chassis somewhere in the unit. Measure from pin 1 of each XLR to chassis with an ohm-meter. With the ground lift switch in one position you should read almost zero, in the other position you should read very high. If not, then there is a short somewhere.
Click to expand...

With the switch in one position it pegs the meter in the same way of you touch the meter's leads together. With the switch in the other position the meter doesn't move at all. Is that what is supposed to happen?
 
maxdown said:
Did the hum go away in the venue(s) when you disconnected from the FOH feed and just had the FBTs connected? I'd sort of assume it would if putting DI boxes on the FOH outs killed the hum. Sounds like a classic ground loop to me. DI boxes act as isolators as well as converting unbalanced to balanced.
Click to expand...

The hum doesn't happen with the FBT's plugged into either the XLRs from output 1 or the 1/4 jacks from output 2.
 
Buuuuuzzzzzzzzzzzzzz

No phantom power. We plugged my FBTs into the XLRs and it's fine but not the FOH. I've played these venues many times with the Ultra with no problem. DI for now. Ugh.
 
Is it both Left and Right? If so then I'm baffled. If it's just one then one of the legs on that output is probably dead.
 
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