# Football Stadium Sound System



## aahgolf (Oct 31, 2006)

The stadium has a new Peavey sound system - PV 14 mixer, PV 2600 amp, PV 1/3 EQ into 3 Impluse 1015 speakers.

The issue to ask for help is the sound volume level sometimes will reduce by itself. When the channel slider is pushed up to re-reached the desired volume level, the volume when then bounch back higher to the level appropriate for the level of the slider. This has happened using 2 different channels on the mixer board.

A computer is used to play mp3 songs into the mixer with a RCA cable to a 1/4" input jack on the mixer. Have used both the headphone outout jack and also the USB output with a Turtle Beach Audio Advantage Micro in the USB jack of the computer into the mixer 1/4" jack - same result from both computer outputs. Two different cables have been used from the computer to the mixer with same result.

Have not tried yet using the CD player included in the system to see if the volume reduction takes place when not using the computer for input. The computer is a 1.86 GHz laptop with 1 GB of RAM on XP only running the sound play program.

Might there be any potential issues with the computer or sound system that would cause this undesired automatic reduction of sound volume? What additional testing could be done to narrow the issue down?


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## koncept (Oct 31, 2006)

alot of people i know perfer to run computers into di boxes, i typicaly do not when using sound cards designed for live sound...i would try running it through a di and try the cd player. are there any cuts on the amps to limit it?? or compressors/limiters in the system?


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## soundman1024 (Oct 31, 2006)

I wouldn't rule the computer out at this point unless you are having similar issues with other inputs. Also try different channels on the mixer. It is possible that one channel is messed up on the board. (Or the main bus for that matter.)


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## soundman1024 (Oct 31, 2006)

Volume changes shouldn't be because of a lack of a Direct Box, however it certainly is good to have one.


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## aahgolf (Oct 31, 2006)

Can you recommend a good (cheap) direct input box for my situation of computer connected into stadium or gym sound systems?


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## Footer (Oct 31, 2006)

aahgolf said:


> Can you recommend a good (cheap) direct input box for my situation of computer connected into stadium or gym sound systems?



If you are running 1/4" (line level) into your console there is no need for a DI. I assume the computer is sitting next to the console (less then 10' of cable), to which a line level signal will run accross just fine on its own. The only reason to use a DI is if you are running a long distance or you have only mic level inputs. Check to see if the problem exist with the CD player before you go buy anything. I am going to say that there is mostly likely a compressor or a limiter somewhere in the system that is set a bit to low. If it is a new system, get the sound company that installed it back in to fix it.


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## mbenonis (Oct 31, 2006)

Footer4321 said:


> I am going to say that there is mostly likely a compressor or a limiter somewhere in the system that is set a bit to low. If it is a new system, get the sound company that installed it back in to fix it.



I had the same thought. It sounds to me like a highly compressed signal.

aahgolf, Do you have any compressors or any "black box" signal processors installed anywhere? Crossovers? Driveracks? Things of that nature?


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## jbeutt (Oct 31, 2006)

considering he has only one input and hasn't tested multiple outputs, you can't really rule anything out. 
It sounds like it could be a compressor in an installed dsp, so definitely check that out, although I don't see the purpose of having a dsp on that rig. I guess it could also, and more likely, be a protective limiter. 

I'd certainly like you to go into more detail on the equipment you're using and give a more specific layout of your signal flow.
Assuming you meant 2 1015 speakers powered by one PV2600 amplifier, you have a big problem there that should be addressed. You're substantially under powering your speakers, which is not good. 
I don't know if this, rather than a hidden limiter, is your problem, but it's probably the first thing i'd look at. 

But it's possible you meant 3(three) 1015s each powered by 1(one) 2600. So let us know about that. 

If your only components are what you described, though, you're going to have to methodically seek out which component is causing this. That firstly requires trying different inputs, like the cd player you plan on putting in. From there, check all possible routing through the console to see if this phenomena changes from output to output. Then lastly, i suppose check your outboard gear and speakers.


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## SHARYNF (Nov 1, 2006)

I would suspect the amp. Can you explain how the amp is connected to the three speakers? It is possible that the amp is set up in bridged mono mode and then the three speakers are all placed across the single output? this could cause problems with the amp as the load could be two low in impedance?

From the description I doubt there is any compressor or dsp, just the 1/3 equ.

A few things to check is to try going from the pc directly into the eq, and see i the problem remains, try going into the amp, and also try the system with just ONE of the speakers attached.

The amp could with improper loading go into a protection mode

Sharyn


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## PhantomD (Nov 1, 2006)

We are having this same problem with a Yamaha mixing desk.

When we faded the lights up to full intensity recently we had a 15 percent increase in volume out of the speakers. Weird. (If anybody has ideas that'd be great)

In your situation, it would certainly seem you are overloading something from further up the line...try reducing gain and "upping the amp".

D.


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## Footer (Nov 1, 2006)

PhantomD said:


> We are having this same problem with a Yamaha mixing desk.
> When we faded the lights up to full intensity recently we had a 15 percent increase in volume out of the speakers. Weird. (If anybody has ideas that'd be great)
> In your situation, it would certainly seem you are overloading something from further up the line...try reducing gain and "upping the amp".
> D.



Get your sound system off of the same power leg as your lighting system. Also check all sheilding of cable and all of your grounds.


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## inspector_gizmo (Nov 1, 2006)

A question for the original poster, how do you have the computer connected? It sounds like you are perhaps suffering some sort of phase cancellation problem as if you are possibly using a Y cable to combine the stereo outputs into a mono input on your mixer. I don't remember the science of all of it, but I know there have been a few postings around here about why you don't use Y cables to combine inputs. If my assumption is wrong, forgive me, this just sounds like the issue you have at hand. Keep us posted. Thanks.


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## SHARYNF (Nov 2, 2006)

I would still suggest you look at the amps and the power to the amps and the loading from the speakers.

If for instance your amp is bridged for 4 ohms and you put in parallel the three speakers all of which are say 8 ohms you are placing about a 3 ohm load on the amp and as such you could easily be running into problems with the output stage attempting to draw too much power. If you should have a significant drop in the line voltage to the amp based on some other major load on the power line you could also have the same problem.

Again, just a suggestion

Sharyn


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## PhantomD (Nov 3, 2006)

Footer4321 said:


> Get your sound system off of the same power leg as your lighting system. Also check all sheilding of cable and all of your grounds.



My apolgies for causing two conversations in the one thread.

But how? The lights are triphase, no matter where I plug anything the lights will be drawing.

When a music department extension was jacked onto our existing building, the power was not upgraded.

As such I suspect a 240V high duty capacitor may have to be placed inline to the compressor for the aircon, that is what I suspect is causing occasional fluctuation/lights browning out etc.


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## MircleWorker (Nov 3, 2006)

Footer4321 said:


> If you are running 1/4" (line level) into your console there is no need for a DI. I assume the computer is sitting next to the console (less then 10' of cable), to which a line level signal will run accross just fine on its own. The only reason to use a DI is if you are running a long distance or you have only mic level inputs. Check to see if the problem exist with the CD player before you go buy anything. I am going to say that there is mostly likely a compressor or a limiter somewhere in the system that is set a bit to low. If it is a new system, get the sound company that installed it back in to fix it.




Same Thought here Too much compression you want to set the theshold a little higher and the release a little shorter, BUT! I strongly urge you to call the sound company who installed it, if you are not use to setting compressors. 
Another thought is if the console you are using is a DJ mixer, sometimes they have a talkover switch that everytime you talk in a channel it will cut out the other channel volumes.


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## Andy_Leviss (Nov 3, 2006)

Two quick things to check:

1)I'm unclear whether you're connecting just one channel from the computer to the console, or both the left and right. If the latter, are you Y'ing them into a single input? If so, this is a big no-no, and could cause all sorts of issues.

2)Although it shouldn't be, get a voltmeter and see if the console is sending phantom power out the 1/4" input. Phantom can do all sorts of wacky things to outputs that aren't meant to take it.


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