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Weird on stage sound issue. K10?


RudyS

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Hi all,

 

Friday at a gig I had a weird sound issue. First 2 sets, no problem and when we were ready for the third set, a very loud low humming/growling sound came out of my QSC K10. I sounded like the amplifier was blown up or something.

 

Here is how I connected everything:

 

Nord E3 and Kurz PC3 mono out into small Alto mixer

Shure SM58 into small Alto mixer.

 

Main out of mixer (with SM58 signal) into channel 1 of K10

monitor out of mixer (with synths signals) into channel 2 of K10.

 

The link outs of K10 were used as feeds for FOH. The post gain line out was used to feed a second K10 for our guitarist to hear me.

 

After the problems occurred I switched off my mixer, but still the K10 made the noise. Our sound guy swapped the K10 with a spare one from backstage. He also disconnected the mixer and put my synths direct in channel 1 and 2. Problem was solved then (though I did not have vocals anymore and our guitarist couldn't hear me anymore).

 

Day after back home I connected everything the same way; No problem at all... Why does this always happen at gigs???

 

Does anybody has an idea? Is it because the lack of DI's? Should I take no risks and buy a better mixer? Was it overload for the K10 to use all its in- and outputs?

 

Suggestions and help is very appreciated.

 

Rudy

 

 

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Was it a 60 cycle hum? If so, that could have been poor grounding at the electrical outlet. I used to carry one of those outlet testers with gigs to verify this. One club that we used to play with had some outlets (in the same cluster) that weren't grounded properly. We would get hum if we used that outlet.

 

 

Otherwise, I use a K10, with no issues.

Yamaha Motif XF6, Yamaha AN200, Alesis Micron, Sonar X3, Arturia Microbrute, Behringer Model D, Yamaha UX-3 Acoustic Piano, assorted homemade synth modules
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I would ALWAYS use a DI, just to be on the safe side. You never know the state of the electrics that you may be dealing with.

 

OTOH, I don't know whether a DI would have definitely solved your problem, sorry.

 

 

 

 

SSM

Occasionally, do something nice for a total stranger. They'll wonder what the hell is going on!
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were you using xlr cables into the k-10 ? I had one a few years ago and it had an intermittent problem of breaking up

or cutting out altogether when I was using it as a wedge on the

floor , the first time it cut out I thought it was blown , when I got it home it was fine . I found out on a qsc forum it was an

issue with the xlr sockets on the k-10 , If I remember correctly

qsc was aware of it and had a fix . I think you can use 1/4

inch jacks to get around it .I ended up trading mine in anyway ,

I was looking for something a little warmer at the time

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Thanks for the help everybody.

 

@piano39, no it was not a 50hz (on this side of the pool) hum. much louder and more growling.

 

@Tusker. I haven't yet read the whole thread you posted, but the video in there sounds much like I was hearing. I am going to dive into that!

 

@bill, I used jacks from my mixer to the K10.

 

Rudy

 

 

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I would have disconnected the sends to the PA 1st to see if that fixed it. Every time I've had a noise in my K10 it's when using the xlr outs to feed the house.

Live: Korg Kronos 2 88, Nord Electro 5d Nord Lead A1

Toys: Roland FA08, Novation Ultranova, Moog LP, Roland SP-404SX, Roland JX10,Emu MK6

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Rudy,

 

I'm may have your answer... ??

 

I use a pair of K10's with my rig, and out of the blue one night at this gig I had an awful noise/hum as soon as my K10's were plugged into the FOH system. I'm pretty sure that it was caused by the sound guy having phantom power turned on the FOH channel that he used to take the feed from my K10. He made a few quick changes at his board and everthing was fine, but it scared the crap out of me because had this awful loud noise coming out of MY K10s!!

 

So I'm pretty sure that in this instance this noise was my K10 reacting to phantom power.. based on how you described your set up... the sound guy took the output into his board from your K10 out.. so is it possible that this was the problem?

 

Could it be the same problem I had??

 

Craig

Craig MacDonald

Hammond BV, Franken-B (A100 in a BV cabinet), Leslies 122/147/44W, Crumar Mojo, HX3 module, Korg Kronos, VR-09, Roland GAIA, Burn, Ventilator

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What Craig said. I've seen it as well, and it's been reported here in other threads as well as discussed how and why it happens.

"I'm so crazy, I don't know this is impossible! Hoo hoo!" - Daffy Duck

 

"The good news is that once you start piano you never have to worry about getting laid again. More time to practice!" - MOI

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Craig beat me to the punch. A few years ago, on the QSC forum, I asked about the possibility of damage to my K8 if I used the pass-through to connect to house sound that might have phantom power. The answer was yes - this was from a QSC engineer.

 

At any gig that I'm going to house sound via my link outs, I speak to the sound guy before we connect anything and make sure he knows in no uncertain terms that having phantom power on my channel might blow my speaker.

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I don't know if phantom power was on on the FOH. I am checking it now.

 

@DanL, did your issues were also happening when no phantom power was there?

 

Could I solve this by using the same setup and putting two DI, on the XLR's feeding the FOH?

 

Thank you all for the help! This place great!

Rudy

 

 

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I had the phantom power thing happen once, with a house system at a casino. That was so loud, there was no doubt something was wrong. The other times I've had noise were just the typical ground loop type stuff, not real loud, but a definite buzz in the speaker.

 

Using DI's to feed the house would be a great solution. Keyboard plugs into the DI, then out of the DI into your K10, with the xlr out going to the house PA.

Live: Korg Kronos 2 88, Nord Electro 5d Nord Lead A1

Toys: Roland FA08, Novation Ultranova, Moog LP, Roland SP-404SX, Roland JX10,Emu MK6

www.bksband.com

www.echoesrocks.com

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Using DI's to feed the house would be a great solution. Keyboard plugs into the DI, then out of the DI into your K10, with the xlr out going to the house PA.

 

Will this solve it? Then the K10 is still feeding the FOH directly? Shouldn't I place the DI's after the XLR-out of the K10? I don't have much experience with these matters, so pardon me if I'm wrong..

Rudy

 

 

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no, the DI goes between the keyboard and K10. You wouldn't use the K10 sends for anything.

Live: Korg Kronos 2 88, Nord Electro 5d Nord Lead A1

Toys: Roland FA08, Novation Ultranova, Moog LP, Roland SP-404SX, Roland JX10,Emu MK6

www.bksband.com

www.echoesrocks.com

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Even just the risk from different grounding of the house PA being fed from the K10's outputs is sufficient to cause a problem (and, as others have mentioned, possible damage to your K10).

 

I bought a stereo Radial Pro DI - built like a tank, has two channels that can either be used for stereo or two independent mono feeds. 1/4" between keyboard and DI input, 1/4" between DI output 1 and my powered PA (usually K10), and XLR output ISOLATED by a transformer going to the house system. Ground can be isolated by a switch. Also a 20db pad to the house system that can be switched.

 

I never hook directly to someone else's system without the DI - I have no control over house wiring or the house system. If the setup sounds bad, that's bad for business. If the setup blows up some of my gear, that's my loss.

 

The DI was a one-time purchase for about $100 or so. Plus a couple of extra cables. Fits right in the bag with the other cables, switch pedals, expression pedal, and so forth.

 

Howard Grand|Hamm SK1-73|Kurz PC2|PC2X|PC3|PC3X|PC361; QSC K10's

HP DAW|Epi Les Paul & LP 5-str bass|iPad mini2

"Now faith is the substance of things hoped for, the evidence of things not seen."

Jim

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A DI is good insurance but it's one more piece to carry, and another set of cables to carry & hook up. 90% of my gigs where I use my K8s I am not going to the house. 99% of the rest of the time I am on the road and not using my K8s anyway.

 

On those few occasions where I use my K8s and also need to send to FOH, I choose to go direct from the speakers and it's always worked fine. The risk of damage is minimal since I usually work with good sound people and as I said, I always make sure to mention the issue before I set up.

 

If there was no phantom power in your setup then it was probably a grounding issue. However, some sound boards do not have individual phantom on/offs for each channel. It's either all of them at once, or in banks of 4 or 8. And a sound person might not want to cop to possibly blowing one of your speakers. Not saying that's what happened but if a setup is rushed, if it's not the regular sound person, if they don't know the board, etc. then mistakes can happen.

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I don't think that phantom was it, beacause it happened at the third set and there was no one using phantom. Ground issues are more likely. I think i'm going to but a better mixer and a DI. Might build a good rack. I hate these issues and do not mind to spend some money one it to prevent problems .

Rudy

 

 

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