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FOH issue...need some help

mesaboog

Inspired
Hey guys,

Had a gig Saturday night. We have some new PA gear and a new fairly inexperienced sound guy. The sound wasn't great overall and I am trying to figure out what I need to troubleshoot on my end so we don't have a repeat performance. Now I am not too familiar with PA systems or the console, so that is why I am posting this question hoping those of you more knowledgeable about FOH routing/consoles can help me pinpoint the problem.

I was running the Axe-Fx balanced output 1. Global EQ flat. My backline QSC K12 was fed by output 2. At sound check, I was told by the sound guy that I was pegging the input on the board, and this is with my Axe-Fx output knob at between 2-3 (or 8-9 o'clock). Is this normal? My sound out front was shrill and trying to dial out the highs on the console EQ did not help much. I never had the time to mess with the Axe's global eq. so I was left playing the gig disappointed with my tone out front and through the stage monitors.

FYI - The console is a Mackie VLZ, I do not know the exact model.

As I have been scratching my head about this all day yesterday, I am wondering if the Axe signal was so hot and could there have been something in the chain that would have caused this? Onboard preamp or something (I am grabbing at straws).

Any words of wisdom on this issue? Need more info?

Thanks in advance guys.
 

Jay Mitchell

Fractal Fanatic
mesaboog said:
At sound check, I was told by the sound guy that I was pegging the input on the board,
Your Axe-Fx signal was going into a mic input. Because most cheap consoles (like the Mackie) use 1/4" jacks for line inputs, I suggest you buy or make an XLR - TRS (balanced 1/4") cable. That will stop the input overload. Unfortunately, there's no quick or easy way to fix the "new PA gear/inexperienced sound guy" syndrome. There's gonna be some pain before that situation gets much better...
 

mesaboog

Inspired
Jay, just one more question. Beyond spiking the signal, to what degree will that mic preamp on that cheap Mackie console affect tone?
 

Sidivan

Fractal Fanatic
The mic preamp is going to affect the tone, but if you go into a line input, it shouldn't be routed through the mic preamp. I'm not familiar with that specific board, but that would be my guess.

The bigger question here is what speakers do you have with this new PA? It's likely that those aren't completely flat either. What I would do is hook everything up to your PA, make sure you're in a line input and follow the routing on the rack to make sure there isn't something that's killing your tone. Then, set the EQ flat on the board and start dialing in the axe fx. That's going to make it easy for the inexperienced sound guy to mix. Just make sure you have your bass player there so you can dial it in around him.
 

mesaboog

Inspired
Thanks Sidivan. Yes, I am definitely going to have to pick up the XLR/1/4" balanced cable & make sure it is line-in next gig. I am not sure of the brand of the speakers. The power amps are QSC and we have 2x15 + horn mains and 18" bottoms. The best way I can describe the tone going through mic input was shrill and HOT (not a good combo). I am sure going correctly through the line-in will make all the difference as the tones I have dialed in sound beautiful through my FBT 12ma and the K12. I agree some EQ will be necessary, but OMG, the other night I was shocked and befuddled at the tone. I thought somebody had swapped my Axe for a Pod :oops:
 

FlyingV

Inspired
you have shrill tone when you have no cab sims on !!!??
Have you routed it the right way ?
On output 2 for your amp and box you need no cab sim ??!!!
Have you checked this ?
 

mesaboog

Inspired
yek, I test my presets at gig volume (stage volume) using K12 as backline.

Because I don't have access to PA other than gigs, that is when we did the soundcheck and ...oh shit. I had no idea I was running through a mic input.

Flying V, backline I am running FRFR K12, not amp cab. I use copy output 1 setting.

I believe the plugging balanced XLR into the mic input on the Mackie is the culprit as Jay Mitchell described. A mediocre Mackie mic pre in the chain is definitely going to color the tone in an unpleasant way, no? Line in should fix her up and eq as needed. I'll report back after next gig.
 

mesaboog

Inspired
yek, I test my presets at gig volume (stage volume) using K12 as backline.

Because I don't have access to PA other than gigs, that is when we did the soundcheck and ...oh shit. I had no idea I was running through a mic input.

Flying V, backline I am running output 2 FRFR QSC K12, not amp & cab. I use copy output 1 setting.

I believe the plugging balanced XLR into the mic input on the Mackie is the culprit as Jay Mitchell described. A mediocre Mackie mic pre in the chain is definitely going to color the tone in an unpleasant way, no? Line in should fix her up and eq as needed. I'll report back after next gig.
 

Jay Mitchell

Fractal Fanatic
mesaboog said:
A mediocre Mackie mic pre in the chain is definitely going to color the tone in an unpleasant way, no?
No. That is not the issue. In fact, the line in uses exactly the same preamp, but it is configured for much lower gain. That's the important part. The mic input is configured to amplify much weaker signals than any line-level device produces, meaning it has far too much gain.
 

mesaboog

Inspired
Thanks for the clarification. hmmm, any idea what is accounting for ice-pick highs that were hardly tamed by the Mackie eq? I know it is hard to troubleshoot without being there.

The thing that is perplexing me is shouldn't the lows become more pronounced going through the PA with the increased watts and 18" bottoms? If anything I would expect to have to dial out some lows. Could crossover point be contributing? I am clutching at straws I know.

I am 99% sure the issue is not the Axe-Fx or the way I have dialed in the presets. They sound perfect at gig volumes through both the K12 and 12ma. I mean I could use the global EQ on Output 1 to try to resolve this, but I would like to resolve the issue at the source rather than mask the symptom with the global eq.

It may be just not so great PA coloring the sound...but my hunch is that there is something amiss in the chain.
 

mesaboog

Inspired
vicknott said:
So, what would sound worse : using unbalanced jack cable or XRL cable to mic input ?
My assumption would be unbalanced XLR (shorter runs) would be a better bet. At least you would not be clipping. If I recall correctly from reading somewhere on here, unbalanced will be roughly -6db difference from the balanced. Unbalanced long runs could require a di box.
 

iggypop

Veteran
OUT1 and OUT2 have both the same output impedance (100 ohms), and a hot output signal as well ( +18 dBu max. ) . So both would sound crappy into a mic input.

Rear Panel Analog Outputs, Output 1
(2) x ¼" phone jack, unbalanced • 100? impedance • Max Output Level:+18 dBu • Dynamic Range:> 105 dB
Frequency Response:20 - 20kHz, +0 / -3 dB • Crosstalk:<-60 dB over full bandwidth

(2) x XLR, Balanced • 100? impedance • • Max Output Level:+18 dBu • Dynamic Range:> 105 dB
Frequency Response:20 - 20kHz, +0 / -3 dB • Crosstalk:<-60 dB over full bandwidth

Rear Panel Analog Outputs, Output 2
(2) x ¼" phone jack, unbalanced • 100? impedance • • Max Output Level:+18 dBu • Dynamic Range:> 105 dB
Frequency Response:20 - 20kHz, +0 / -3 dB • Crosstalk:<-60 dB over full bandwidth
 

Jay Mitchell

Fractal Fanatic
vicknott said:
So, what would sound worse : using unbalanced jack cable or XRL cable to mic input ?
You do not want to send a line-level signal to a mic input. Of those two scenarios, the 1/4" cable to line input is the only viable way to go.
 
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