Sound reinforcement: How to reduce feedback roar in the stage monitors using a graphic equalizer

This excerpt from "The Sound Check Trainer" (a sound engineer training program) provides a very basic example of locating and eliminating feedback in a stage monitor system. In this video, the kick drum is causing a feedback roar that must be eliminated during sound check in order to insure a great live sound.
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Category:

Howto & Style

Tags:

• sound reinforcement
• eliminating feedback
• feedback control
• graphic equalizer
• live sound
• church sound
• concert sound
• sound engineer training
• tips & tricks
• educational

[nyaudioengineer]

I do no agree with this method. By cutting the frequency at the specific monitor graphic EQ, you have now changed the sound of EVERYTHING in that monitor. With todays mixer technology, the parametric CHANNEL eq can be far more effective. If the kick drum was feeding back into the drum monitor at 100hz, it would be far more effective to use the kick drum channel eq to cut 100hz, thus eliminating the feedback while maintaining the sound of all the other instruments in drummers mix.

[rfmedia2]

@nyaudioengineer

We designed this and other videos to help beginning sound engineers. They will likely not have the luxury of an individual monitor console with mic splitters, etc.

Most of the time they are sending one or more pre-fader aux. mixes to the monitors. This prevents individual EQ control on each channel.

[AntiPirateSquad]

@nyaudioengineer Yes, perhaps if one has a on stage engineer with a separate console! Otherwise it'd be a preposterous idea to EQ the trouble frequencies out of the kick channel as this would affect the front of house where the trouble frequencies (monitor based) might not be an issue! If there's a monitor set up that's got a peak somewhere then it's best 'reduced' to flatten it out and get it back to 'normal'. Wouldn't you agree in hindsight?

[AntiPirateSquad]

@ORayDizzyO

You don't EQ the channels to accommodate monitor roar / feedback .... you'd be changing the way it all sounds front of house... why would you want to go and do that?

You use EQ on the monitors that appear to have feedback problems and very simply with a straight forward EQ such as above, say 32 / 64 band would be ideal, per monitor ... and leave the channel strip eq on you desk to do the job of FOH.

That's the norm, unless you have a separate on stage mix that is.

[TheDubstepDrummer]

@TheDubstepDrummer ....cont... The most common configuration would be GEQ for removing unwanted frequencies from monitor wedges and FOH ... unless you're insistent on having an adjustable Q maybe?

Maybe I'm wrong, perhaps these days absolutely everything is EQ'ed using parametric EQ's .. I would have thought that'd be quite fussy in a rack, each module for one of 20 monitors... much easier to have a nice uniform stereo GEQ x 10 and use a side per wedge, just quicker in my humble onion :-)

[TheDubstepDrummer]

@ORayDizzyO Sorry, you missed my point, I wasn't saying parametric is 'old hat' ...indeed it's of course widely used... but it's no 'new discovery' .

Quote: "most engineers, TRAINED engineers prefer parametric controls to a GEQ."

Sorry mate, that's just a silly generalisation, I don't know where you were 'TRAINED' as you put it .. but Parametric and GEQ serve different jobs when it comes to sound reinforcement; and yes, you use GEQ for removing unwanted frequencies, and PMEQ for channel EQ.

[ORayDizzyO]

@nyaudioengineer I agree with your way of thinking. However, depending on the set up of the band, if there are a large amount of vocals or acoustic instruments contributing to problematic feedback, wouldn't it be smarter to use the GEQ to take out feedback overall, other than going into each and every channel and fixing it?

[ORayDizzyO]

@AntiPirateSquad If you ever use analog mixing consoles, which is held in most simple venues, you will find parametric eqs being used. And most engineers, TRAINED engineers prefer parametric controls to a GEQ. Simply because it's organized to four separate sweepable bands. Parametric eqs are still being used today, everywhere.

[lavyheed]

@nyaudioengineer exactly pal....fix the problem at the source before resorting to drastic cuts on graphics.....

[nyaudioengineer]

Graphs should be used to correct the overall sound relationship of the wedge to the room (stage). Too honkey? Fix it with graphs. You should be able to play your favorite song throuh the wedge and have it sound good. If you hack graphs for feedback supression, the wedge will sound wrong.

[nyaudioengineer]

My major gripe is when graphs are used to fix feedback issues for lets say a lead vocal, it messes up the sound of everything else in that mix. What are the most common sources of feedback? Vocal Mics, Acoustic Instruments (insert your source here). Why hack up a good sounding wedge just to tame a few sources?

[nyaudioengineer]

@AntiPirateSquad, Yes I stated this and agree! I was talking about using a dedicated monitor console in one post as well as todays mixer technology where you can use one digital console with a layer for FOH and a layer for MON thus giving you seperate eq for each side using one console.. sure parametric eq is old tech but now it has come a long way esp. in the digital relm where you have full control with dynamics on every channel.

[AntiPirateSquad]

@nyaudioengineer ps.... Parametric EQ was invented over forty years ago .... that's not really 'today's' mixer technology forte.