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[Andrew Henderson]

Hey everyone. One of the racks I use for running sound for small bands doubles as my personal "gig rig" that I use when I'm gigging as a musician. It's an 8-space rack that contains a guitar FX processor, an X32 rack, and an IEM transmitter. I gig with it regularly. The two normal scenarios are:

• Playing with my main band (the X32 in this rack is used as the mixer, and I bring my own PA)
• Playing as a member of another band (the X32 mixes my guitar and vocals to my IEM the way I like it, and I send outputs to FOH. Depending on the scenario it could be any or all of these sends: my vocal, guitar L/R, software synth L/R, click, backing tracks L/R. I run the sends via XLR out of the X32 rack directly into the band's snake or console.

I never have noise issues when it's my band, my mixer, and my PA. Until this month, I'd never run into noise issues playing with other bands either.

There's a band I've been rehearsing with (twice so far). We're rehearsing on one member's church's stage. The first time, I just gave them a mono guitar send. It sounded great within my rack and in my in-ears, but there was a buzz when it hit their sound system. We just dealt with the noise it rather than troubleshooting it; it wasn't really audible once we were all playing.

At the following rehearsal, I'd be both singing and playing, so I planned send them a mono guitar signal and a mono vocal signal. I brought a couple of XLR ground lift barrels with me, thinking that using them in between my mixer outputs and theirs would do the trick with the noise. No dice; still noisy. Again, we just dealt with it for the night, and I made a note to bring some DI boxes next time, to isolate the signal.

I'm assuming we just need isolation transformers between my mixer and theirs, but in case that isn't the issue, I want to make sure I'm prepared with some other tools to nip this in the bud at the next rehearsal. I plan to bring an Ebtech hum eliminator (2-channel isolation transformer), 2 regular DI boxes, and an Ebtech HumX (AC line). Are there any other tools I should bring with me to troubleshoot?

FYI: Taking my X32 out of the loop or splitting guitar and vocal signals off to FOH before my X32 isn't a good option in this case. Im using the X32 as an audio interface too, and my sends to FOH include software effects on vocals and guitar, and a software synth used with a MIDI guitar pickup.

Thanks in advance!

[Erik Jerde]

Any chance there was phantom on the channel of their console you were plugging into?  Yamaha outputs are noisy when they get phantom.  I don't know if the X32 has the same issue but it's a thought.

[Andrew Henderson]

Any chance there was phantom on the channel of their console you were plugging into?  Yamaha outputs are noisy when they get phantom.  I don't know if the X32 has the same issue but it's a thought.

That is a great thought. I hadn't even thought of that. It seems like the hum was mainly on my vocal line this time around. It could just be that their console had phantom power on my guitar channel the first time, and the vocal channel the second time. I'll check with the guy who was setting us up on the sound system.

[Luke Geis]

some mixers have global phantom power. While it usually isn't problematic, there is off course the likelihood that it is. Be certain of that first. Electrical gremlins are almost always the simplest thing. That is one such thing that can be and is very simple.

[Dan Mortensen]

That is a great thought. I hadn't even thought of that. It seems like the hum was mainly on my vocal line this time around. It could just be that their console had phantom power on my guitar channel the first time, and the vocal channel the second time. I'll check with the guy who was setting us up on the sound system.

Were you planning to use the DI boxes by running your outputs into them and then into FOH? If not, why not? Putting a DI on each console output that you are sending them should do the trick, and that's where you have the ground lift, not on any AC.

Try treating your Rack like a keyboard with an XLR output that needs to go through a DI to get into the PA.

You may also be able to solve it with the other devices you were going to bring to keep the signal in XLR connectors. Whichever is easier.

[Andrew Henderson]

Were you planning to use the DI boxes by running your outputs into them and then into FOH? If not, why not? Putting a DI on each console output that you are sending them should do the trick, and that's where you have the ground lift, not on any AC.

Try treating your Rack like a keyboard with an XLR output that needs to go through a DI to get into the PA.

You may also be able to solve it with the other devices you were going to bring to keep the signal in XLR connectors. Whichever is easier.

Yes, I figured adding a DI or other transformer was the next step. I’m glad to hear you think so too.

Don’t worry, I hadn’t even considered pulling the ground on the AC line.

I’ll try that at the next rehearsal and report back. If this is the issue, I may just add an 8-channel iso split like the Art S8 to the rack so that I don’t have to worry about this in the future.

[Keith Broughton]

I'm assuming we just need isolation transformers between my mixer and theirs,

YES!

[ProSoundWeb Community]