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Author Topic: wedges feedback  (Read 8372 times)

John Roberts {JR}

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Re: wedges feedback
« Reply #10 on: April 15, 2014, 05:54:28 PM »

Actually, I like mine post eq. Sometimes I do JR's "dip the gain" trick with eq instead of simple gain.
You have to know the frequency to do that. Perhaps with FLS GEQ. 

Riding the wide band gain will be the quickest and most reliable way of getting the feedback stopped and source identified. Then you can push the gain up while tweaking the EQ to maximize the GBF. When you have the system growling at two or three frequencies simultaneously, you have it EQ'd as good as it will get. Then return the slider (or trim) back down to normal mix level.   

JR
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Bob Leonard

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Re: wedges feedback
« Reply #11 on: April 15, 2014, 06:35:36 PM »

Agreed, that's what level meters and faders were made for.
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Luke Geis

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Re: wedges feedback
« Reply #12 on: April 15, 2014, 07:30:05 PM »

I would say it simply takes years of experience. It is even more fun distinguishing if the feedback is from FOH or monitor world!!!! The two are different and has their own set of ramifications. In either case it's always the FOH engineers fault. He is the only one people see and can walk up to directly and point at. All kidding aside, lets see how we can learn.

For me it's always about knowing the frequency first so I know which one to cut when I do find the culprit. The next step I do is take notice in which wedge or wedges has the most mics in it ( usually vocal wedges ). I then ( as others have mentioned ) look for levels acquired in each wedge. It is not likely that a low level wedge is going to have sailing feedback in it. The next tell tale is who stopped doing something, or did something different at the time the feedback occurred?  This will usually be the guy that has the offending wedge, but not always...... Any wedge that shares him is likely going to also have the feedback in it as well!!!! This is the reason why I try not to send every musician into every wedge..... The more you have going around, the more likely that feedback can occur and be that much more difficult to discern point of origin.

This brings us to the next point. The Q wedge is really important!!!! Not having one can make the monitor engineers job difficult, especially when mixing more than 4-5 mixes. That doesn't sound like many to a more experienced engineer, but it makes a big difference in speed and quality of each members mix. The other big + is that you can listen to any mix, or combination of mixes to discern problems. In this case a mix that is one the verge of feedback can be easily noticed by the faint hollow sound that usually prefaces the oncoming squeal. You can do this with headphones too if need be. Just listen in on each mix one by one. You will probably be able to hear the one which is close to feedback. Then you can apply the appropriate EQ correction to minimize the likelihood of feedback! If your fortunate enough to have dedicated monitor channels ( like the channel splitting of the LS9 ) you can simply eq the specific problem channel. Again, usually vocals, you simply PFL the individual channels in your headphones or Q wedge and remedy the problem with as little EQ as it takes to ratify it. Do not try and make the mix sound beautiful when using headphones or Q wedge though. This should be done while listening to the mix at the musicians actual playing spot. Removing feedback is one thing, but trying to play god with the channel EQ when not actually being in the musicians position, can be a sin.....

The hardest challenge is quickly discerning the problem frequency and where it is coming from. Experience helps get you to the conclusion quicker. After a while it becomes second nature. I find that the largest part of many engineers problems is trying to get a mix as loud as possible by excessive EQ cutting. You can only get so much and actual level VS. perceived level are different. Basically just because the channel level is higher in the mix doesn't mean the mix is louder. A loud mix is one that is very stable up to a degree ( usually about the time three simultaneous tones are noticed ) with as little EQ as possible. The specific problem channel can then be EQ'd to finish the job if need be. The popular method of flattening a monitor mix with pink noise is kinda moot in reality. The goal is GBF and acquiring a clear loud mix. A flat monitor will not get that result, it simply makes the monitor less of the overall problem. Don't be afraid to add EQ to increase level at spots that may benefit for clarity and increase GBF potential. Gain is the actual level acquired, not where the fader is at on the channel. I also like to be an evil engineer at times. I basically don't try an second guess the band members. If they don't ask for it, I don't give it to them. This seems mean and counter intuitive to the job, but in reality it reduces stage volume and possible issues. If a member needs it, they know to ask and I will be glad to give it to them at that point. Also don't show all your cards right off the bat. Giving the musician the max level you can acquire right off the bat will lead to louder stage volumes and you can end up painting yourself into a corner. If you give all you have to give then your left with no room to give that little bit more. Don't be afraid to say no either! If you have nothing left to give, then tell them that's it. There is no point in destroying equipment simply because the musicians refuse to work within the parameters. If you dealing with A national acts you don't say no, but you know that your working with equipment and probably have a level of skill where you never have to say no! Local festival level acts and bar bands that are not paying enough to have the equipment at their wanton disposal, don't get the same rights. You have to be able to tell them no when the limits are reached. It's a team effort in which you agree to give them all you can and they must agree to work within the limitation of you and the equipment's ability.
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Patrick Tracy

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Re: wedges feedback
« Reply #13 on: April 16, 2014, 01:40:38 AM »

You have to know the frequency to do that. Perhaps with FLS GEQ.

Channel eq filters are pretty wide. I can generally hear the frequency well enough to know which band to dip.

Luke Geis

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Re: wedges feedback
« Reply #14 on: April 22, 2014, 03:38:55 PM »

Some channel EQ's are different though....... Some narrow the Q as you decrease the gain. Many with 3 bands have very wide Q's ( to make them more musical ) and others are rather well fixed Q no matter what the gain is set for. In the case of the LS9 which has the choice of TYPE-1 and TYPE-2  eq filters there is even more of a question mark.

I was taught this and it works well. The graphic eq ( the one inserted into the monitor path ) is the axe and the channel strip eq is the stiletto. Basically the graphic is used to eliminate the bulk of the problems and the channel eq is used to get the fine minute things fixed. teh less you cut the more volume you have.
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Steve M Smith

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Re: wedges feedback
« Reply #15 on: April 22, 2014, 03:56:40 PM »

In either case it's always the FOH engineers fault. He is the only one people see and can walk up to directly and point at.

He's also the one who gets asked if he's working the lights!

Basically the graphic is used to eliminate the bulk of the problems and the channel eq is used to get the fine minute things fixed. the less you cut the more volume you have.

As far as the graphic is concerned. it's the opposite of that.  By cutting the resonant frequencies, you can bring everything else up.


Steve.
« Last Edit: April 22, 2014, 04:00:30 PM by Steve M Smith »
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Luke Geis

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Re: wedges feedback
« Reply #16 on: April 23, 2014, 06:01:14 PM »

^^^^^^^^^^^^

Yes and no Steve. Yes you can bring things up by eliminating the resonant frequency. But you will always find another feedback frequency as you continue to raise the gain. That is why after you acquire three tones, you are considered to be done. This should net you the lowest number of cut frequencies with the highest level of possible gain. In theory anyway. As you start hacking away with the graphic EQ you start eliminating more and more actual gain. Remember perceived and actual are different. Just because the fader is higher doesn't mean there is more db pouring out of the speaker.

One way to test this is to use a db meter set for whichever setting you like. Run the system with very little cuts in the EQ and get the mic as hot as you can and talk into the mic. Take a reading. Now hack the EQ to high hell to eliminate all the feedback you can and retest. My bet is that you have a lower db reading on the meter after the EQ hacking is done. There is a break even point basically. Once you get rid of the sailing frequencies with the graphic eq you should have good usable gain that will allow you to fine tune with the channel eq. The system will either be stable or not? A more stable system may not always mean more actual level. Where conversely, an unstable system doesn't always mean that your getting more level either. There is a break even point where the number of frequencies cut still allows for plenty of actual level that is stable, but not so stable that it reduces the actual level that can be acquired. My saying is that a monitor system isn't supposed to sound pretty, your supposed to be able to hear it. If you get the level you need first, then you can work on making it sound pretty.

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Jim McKeveny

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Re: wedges feedback
« Reply #17 on: April 24, 2014, 09:38:49 AM »

a monitor system isn't supposed to sound pretty, your supposed to be able to hear it. If you get the level you need first, then you can work on making it sound pretty.

Thank you Luke. This fact has somehow been obscured.

"Wedges Feedback". Really? .."Gasoline Burns" is a topic on the IC Engine Forum.

Monitors should have the minimum amount of information fed to them so the performer can do their job and not encroach on audience/main PA experience.....Or that was the theory.

How about this? : Return to/establish basics -  Feedback is usually through vocal mic channels. Match those mics, match trims on those mics, match mix(es) output(s), bring monitor mix(es) up to threshold of feedback, listen, and apply corrective (negative I hope) filtering to mix or strip.

Make audio friends and go hear a good wedge/mix to help identify where yours are falling short.

IMO this should be a Lounge topic...
« Last Edit: April 24, 2014, 10:27:50 AM by Jim McKeveny »
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Nicolas Poisson

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Re: wedges feedback
« Reply #18 on: April 28, 2014, 07:12:52 AM »

Also, trying to raise levels during the soundcheck (or between the soundcheck and the show) will tell you who might annoy you later.
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Re: wedges feedback
« Reply #18 on: April 28, 2014, 07:12:52 AM »


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