Anyone experience this on stage?

DannyP

We were playing a festival a couple of weeks ago and I noticed my guitar sound was strange as though some sort of modulation pedal was on.

I checked my board and there were no mod pedals on. I then noticed I couldn't hear the odd sound at other positions on stage, just when I was standing by my mic.

I had an AC30 on a stand blasting my bum and a wedge in front of me.

Could it have been a weird phase relationship between amp and monitor? Either that or soundman playing silly-buggers, but I doubt it. Anyone had this before?

jasonbone75

Slight time delay would give you that modulation i.e. your ears get the same signal but a few ms apart depending on your position and the size of the venue - that would potentially chorus/modulate

Edit - think "sloppy double tracking" lol

Cirrus

Yeah, @jasonbone75 has got it I think. I've experienced exactly the same thing. The wedge will have been out of phase with the direct sound from the amp, possibly the wrong polarity too (made more likely by the fact it's pointing in the opposite direction by the cab speakers). And typically monitoring your cab from a close mic gives you a lot more upper mid/ high end than you get from a cab that's not pointing directly at your head, too.

I also wonder if open back combos are more prone to it since they're inherently more phasey anyway, as part of their sound - since you've got the sound unimpeded to come out the back of the cab, bounce off the wall, and then back at you.

This is a part of the reason why I prefer no amps in my wedge, and to monitor from my own backline - less chance of a phasey, washy mess. The main reason is that it clears the monitor mix for vocals.

DannyP

I think you guys have nailed it. It was definitely a phasey, washy, chorusy sound. There was no backwall to speak of though, as it was a marquee.

I need guitar in the mons as I'm over the other side of the stage for part of the set. If we'd had more time for a proper sound check (often impossible at festivals!) I might have had no guitar in the mon by my amp, but plenty in the mon at the other side. Something to think about in future for sure...

I figured out quickly that it was a stage-only problem and wouldn't affect the FOH sound, but it's distracting when you don't really know what the audience is actually hearing!

Cirrus

Ah, yeah ok, an outside gig. Yep, I've *never* had pleasing onstage sound outdoors with an ac30. It always sounds middy, shouty, with no balls. To a mic right up against the speaker it won't make a difference so FOH sound would have been no different than an indoor venue.

Danny1969

Other issues that can cause problems are digital desks, which will put the signal slightly out of phase with the original and it noticable more with IEM's than wedges

Out of phase mic leads. A mic cable with pins 2 and 3 swapped  over one end will still work perfectly but will put the signal 180 degrees out of phase. People buy a single mic lead, it works perfectly and they never consider this issue but if you then use that cable as a feed for an active monitor or PA speaker ... or worse of all on of a pair of overhead mics you will run into problems. 

My rule with festivals is always crank your backline for yourself and get a rough mix of everything else in the wedge in front. Then you physically mix the balance by standing nearer or further to the backline or wedge. 

I played the big top at Victorious festival a weeks ago and I cranked the supplied AC30 right up, sounded glorious !

DannyP

It was definitely a digital desk.