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Author Topic: distortion help  (Read 4621 times)

John Luty

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distortion help
« on: November 22, 2012, 07:02:07 pm »

Ok first set sounded great second set was good too but by the end of the third set vocals were getting distorted .Is it possible that the amps are getting hot? could it be that the speakers are getting weak? I didn't make any changes other than SLIGHT changes like turning up a solo then dropping it back down 
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Jeff Young

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Re: distortion help
« Reply #1 on: November 22, 2012, 07:22:14 pm »

Ok first set sounded great second set was good too but by the end of the third set vocals were getting distorted .Is it possible that the amps are getting hot? could it be that the speakers are getting weak? I didn't make any changes other than SLIGHT changes like turning up a solo then dropping it back down

Its my understanding that as the night wears on temperature changes, humidity changes and the like can alter system responses. Singer could be overexerting, or the system is seconds away form detonating. Pretty sure there will more informed answers however.
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Re: distortion help
« Reply #2 on: November 22, 2012, 07:27:23 pm »

Ok first set sounded great second set was good too but by the end of the third set vocals were getting distorted .Is it possible that the amps are getting hot? could it be that the speakers are getting weak? I didn't make any changes other than SLIGHT changes like turning up a solo then dropping it back down

Not enough information.
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Scott Harris

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Re: distortion help
« Reply #3 on: November 22, 2012, 09:18:31 pm »

How did it sound in headphones?  Was it only distorting on the vocals?
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Robert Weston

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Re: distortion help
« Reply #4 on: November 22, 2012, 11:29:14 pm »

Ok first set sounded great second set was good too but by the end of the third set vocals were getting distorted .Is it possible that the amps are getting hot? could it be that the speakers are getting weak? I didn't make any changes other than SLIGHT changes like turning up a solo then dropping it back down

Did you meter the vocal channels?  Did you meter any of the channels?

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Tim Perry

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Re: distortion help
« Reply #5 on: November 23, 2012, 01:34:39 am »

Ok first set sounded great second set was good too but by the end of the third set vocals were getting distorted .Is it possible that the amps are getting hot?

probably not

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could it be that the speakers are getting weak?

probably not

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I didn't make any changes other than SLIGHT changes like turning up a solo then dropping it back down

Often the band plays louder as the night wears on.  Even if you didn't push anything up you may have either exceeded the system limits or run into a gain structure issue (maybe preamp overload or running out of headroom at some point in the audio chain).
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Mark McFarlane

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Re: distortion help
« Reply #6 on: November 23, 2012, 02:42:13 am »

...
Often the band plays louder as the night wears on.  Even if you didn't push anything up you may have either exceeded the system limits or run into a gain structure issue (maybe preamp overload or running out of headroom at some point in the audio chain).

+1.

Did you recheck that the preamp gains were set properly during the third set?  Are you watching them for overdrive as the night wears on?  The tendency for bands to 'get louder' (at least at my lowly level) happens in every show I do requiring adjustment to the preamp gains throughout the night to keep them from clipping.
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Mark McFarlane
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Jordan Wolf

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Re: distortion help
« Reply #7 on: November 23, 2012, 10:46:36 pm »

Ok first set sounded great second set was good too but by the end of the third set vocals were getting distorted .Is it possible that the amps are getting hot? could it be that the speakers are getting weak? I didn't make any changes other than SLIGHT changes like turning up a solo then dropping it back down
John,

Are you listening to the mix constantly, or are you mixing in-between playing?  Also, if you're not out in the audience area, what you're hearing may not be reflected in the audience as a whole.
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John Luty

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Re: distortion help
« Reply #8 on: November 23, 2012, 11:05:07 pm »

John,

Are you listening to the mix constantly, or are you mixing in-between playing?  Also, if you're not out in the audience area, what you're hearing may not be reflected in the audience as a whole.
Yes I'm just the sound guy for my son's band so I was FOH  the whole time .The distortion wasn't bad but it was bugging me (I'm the type of person that if I'm going to do something I'm going to make sure everything is perfect )
I'll be the first to admit I don't know everything about running sound and every time I do it I learn something Just trying to eliminate future problems
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Re: distortion help
« Reply #9 on: November 23, 2012, 11:52:25 pm »

Yes I'm just the sound guy for my son's band so I was FOH  the whole time .The distortion wasn't bad but it was bugging me (I'm the type of person that if I'm going to do something I'm going to make sure everything is perfect )
I'll be the first to admit I don't know everything about running sound and every time I do it I learn something Just trying to eliminate future problems

Go back 5 posts to Roberts question.

Do you have headphones and know how to solo the channels?  If so, is the distortion present when soloing a channel?

Check each segment of the signal path and find out at what point the distortion starts.

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John Luty

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Re: distortion help
« Reply #10 on: November 24, 2012, 06:42:42 am »

My board (Peavey PV 20 ) doesn't have a solo so no I didn't do that and yes I could hear some distortion in the headphones 
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Re: distortion help
« Reply #11 on: November 24, 2012, 08:43:26 am »

My board (Peavey PV 20 ) doesn't have a solo so no I didn't do that and yes I could hear some distortion in the headphones

So the distortion is likely happening within the board itself.  If it's functioning as it should and doesn't need any repairs, either the input gains are set too high and you're picking up distortion there (indicated by only specific sources distorting) or the summing amps which combine the individual channels are being overloaded.

How are you setting your input gains if you have no "solo" or "cue" button?  One likely scenario is that you're setting your channel input gains too hot.  With a bit of "creep" in the levels coming off the stage over the course of a few hours, this could put you over the top with your little Peavey desk.

Something is changing between the first and last sets.  You just have to figure out what.  Operating your inputs hot is likely to be the first place to look.

Again, how do you determine your channel input level settings?
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Mark McFarlane

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Re: distortion help
« Reply #12 on: November 24, 2012, 09:00:46 am »

My board (Peavey PV 20 ) doesn't have a solo so no I didn't do that and yes I could hear some distortion in the headphones

John, your mixing console seems to have a fairly foolproof clip light on each channel, just above the faders.

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Clip/Mute LED
This light normally indicates that the channel signal level is nearing the overload point, but it also lights when mute is engaged. The clip indicator circuit monitors the signal at many points in the channel to ensure that it catches all instances of clipping. It illuminates at +19 dBu and warns that the gain or EQ boost should be reduced. When it lights, roughly 3 dB of headroom remains.

If this light starts lighting red you are 'almost' at the point of distortion for that one channel.  Try to keep the lights out of the red by turning down the gain knob at the top of each channel strip (or turn down the EQ if you have a lot of EQ boost on a channel).  If you turn the gain all the way down and are still in the red, then there are a variety of different fixes depending on what the input is (a keyboard, a mic,...).

The Peavey manual gives instructions for how to optimally set the gain knob for each channel.  This is an important step, and it may need to be repeated during the night as the band gets louder. http://www.peavey.com/products/index.cfm/item/699/116338/PV%26nbsp%3B20%26nbsp%3BUSB

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Gain
This control establishes the nominal operating level for the channel.
The input gain can be adjusted over a wide range to compensate for soft voices or very loud drums. To maximize the signal-to-noise ratio, the gain should be set to the proper level, with the channel Fader (12) set to 0. If the clip LED comes on and remains lit, try reducing the gain.

There are also clip lights on the effects unit and on the master fader.  In general, you want to avoid having any of these light up red during the show.  An occasional red blink isn't too bad...

FWIW, overdriving channels into distortion is the most common cause of distortion that I see, time and time again, when helping new people learn to mix, so I'd look here first.
« Last Edit: November 24, 2012, 09:04:34 am by Mark McFarlane »
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Mark McFarlane
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Re: distortion help
« Reply #13 on: November 24, 2012, 10:23:38 am »



The Peavey manual gives instructions for how to optimally set the gain knob for each channel.  This is an important step, and it may need to be repeated during the night as the band gets louder.

I tried the link and the PDF manual is tedious to say the least.  Here's what I imagine they might say:

1.  With signal present at the input, raise the gain (trim, pre-amp, whatever) until the clip light blinks red, then back off a bit.

OR

2.  Set the Master fader and the channel fader to "0", then raise the channel gain until the mains output LED's show a level of -3.  Be sure to return each channel fader to its lowest point after setting the gain this way.  You only want the meters to read the channel you're adjusting.

Option #2 lets you use metering for a more precise setting.

DR
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David Parker

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Re: distortion help
« Reply #14 on: November 24, 2012, 10:59:36 am »

Ok first set sounded great second set was good too but by the end of the third set vocals were getting distorted .Is it possible that the amps are getting hot? could it be that the speakers are getting weak? I didn't make any changes other than SLIGHT changes like turning up a solo then dropping it back down

one common mistake when learning to run a sound board is to gradually turn the channel faders up when something isn't loud enough. After a while the overall mix is too loud, so they turn down the master fader. After repeating this exercise many times, every channel fader is way up and the master fader is way down. There's an old saying that was spawned by this, never have a channel fader above the level of the master fader. This is not a hard set rule, but it's something to watch. You can overload the summing amps ahead of the master fader. In other words, no separate channel clipping, but the sum of them all clipping ahead of the master. Knowing what to turn down is just as important as knowing what to turn up.
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John Luty

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Re: distortion help
« Reply #15 on: November 24, 2012, 03:15:54 pm »

David I think you are on to something I did have a clip light on a vocal channel that would blink (maybe too much ) and I did ask my son if they were turning up their amps on stage ,which they were ,so the over all mix was screwed up .That's why I use this forum a TON OF GOOD PEOPLE THAT ARE WILLING TO HELP
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Re: distortion help
« Reply #16 on: November 24, 2012, 03:31:17 pm »

David I think you are on to something I did have a clip light on a vocal channel that would blink (maybe too much ) and I did ask my son if they were turning up their amps on stage ,which they were ,so the over all mix was screwed up .That's why I use this forum a TON OF GOOD PEOPLE THAT ARE WILLING TO HELP

This is what happens when a vocalist "sandbags" the sound check.  Not matter what you say, most singers will not give you their performance level at sound check, so you have to hedge your bets and either set their input gain low to begin with or be prepared to lower it once the action starts.

The main problem here is that any change in input gain will affect both the mains and the monitor mix, so if and when you lower the channel input gain on the offender, you have to remember to then boost the monitor aux send for that channel to compensate.
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Re: distortion help
« Reply #16 on: November 24, 2012, 03:31:17 pm »


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