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wedge monitor feedback


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setting up a p.a. for a club setting. Have 4 Yamaha SM15V wedges. I've got 4 seperate monitor mixes and have a 15 band EQ for each monitor.

 

Right now just mainly running vocals through the monitors. Have some loud bands playing and having trouble getting the vocals loud without feedback.

 

I've tried a very little bit trying to use the EQ's to help out. What frequencies are usually the culprit?

 

Would using a noise gate be the ticket?

 

How about a compressor?

 

Very "green" in this area. Any help appreciated.

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A 31 band EQ will be a better tool to help you get the most gain before feedbak.

 

The frequency that feeds back depends on many things. Mic, Speaker, room, and background noise all have a part in determining what frequency feeds back.

 

When I started out I bought a "Real Time Analyzer" (RTA) . It looks like an EQ, but has little LED bars instead of sliders. It comes with a mic and whatever sounds it hears those frequencies will "pop up" on the LED bars. I simply use it as a feedback locating tool. When I hear feedback, I whistle it into the mic (or an octave above or below) and that's how I find the right frequency to pull on the graph.

 

Over time you ear will learn to ID the frequencies without asistance.

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When I started out I bought a "Real Time Analyzer" (RTA) . It looks like an EQ, but has little LED bars instead of sliders. It comes with a mic and whatever sounds it hears those frequencies will "pop up" on the LED bars. I simply use it as a feedback locating tool. When I hear feedback, I whistle it into the mic (or an octave above or below) and that's how I find the right frequency to pull on the graph.


Over time you ear will learn to ID the frequencies without asistance.

 

 

Really great idea!!

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I am not a big fan of compressors in the monitors, though in extreme situations they can be useful.

 

I NEVER use gates on vocal monitors.

 

As for how to get the most gain before feedback, I can offer the following tips:

 

- Always start with a flat EQ

- Always use the same vocal mics on the same mix (different mixes can have different mics if you want, but becareful when adding a mic from mix 1 to mix 3, etc)

- Using the same type of vocal mic across the stage will make things simpler

- I will usually pull the first offending frequency on an empty stage, and only by 3db or less.

- NEVER try to get max volume out of a wedge without the band there and playing. The reason for this is that the frequencies that will feedback in a quiet empty room may not be the same ones that will feedback with a band playing at show volume. Plus, you have variables like:

 

- How loud is the singer?

- How is the singer holding the mic?

- What position is the singer relative to the mic?

 

If you try to get max volume from a wedge in an empty room, all you will end up doing is hacking away at your EQ until you have removed a buch of volume and none of your EQ changes will apply to that nights show.

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No! No! No! NEVER Compressers in monitors (at least that's my creed). A compresser will only give you less GBF (and certainly never more). The only time I'd EVER use a comp in the monitors is for a very very low volume stage (and even then I'd try to talk them out of it). When a compresser becomes active (recieves signal past it's threashold) it TURNS DOWN the signal. When the signal goes below it's threashold (I.E. the singer stops singing) the compresser TURNS BACK UP (and if you were near the feedback threashold you are now above it).

 

I have used a gate on a kick mic a few times to eliminate that slow building low end feedback which was being transmitted through the drum riser. In the end it was a cheat since a better monitor placment would have been a better solution. A noise gate would be usless in stopping vocal mic feedback.

 

:thu: for a 1/3 octave GEQ and a RTA (a good true parametric EQ is even better but no where near as user friendly). A different way is to connect the boards cue output to the RTA's line input. This can help you isolate it down to which mix (or even mic) is causing the problem (sometimes it's visualy obvious, but sometimes.....).

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How about looking at everything besides the monitors?? How loud are the bands? will the PA handle the room for a good full mix? Tell the bands to turn down.... I run a lot of little rock rooms with adequate PA's and planty loud monitors, but even 500 watts can't fight with a rippin' loud half stack that is

 

31 bands would be better, 15 should be *OK*, just have to figure out what the problem is....

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Mic selection is another area you can consider. There are audix mics out there that have impressive rejection, the OM5 and OM6 for example. But you have to be careful in that if the singer doesn't "eat" the mic, it can be hard to pick up their vocals using those mics. It's a tradeoff.

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What frequencies are usually the culprit?


 

 

The frequencies that cause feedback are set up by the difference in distance between the mic and monitor and the speaker and monitor (in simplest terms). A comb filter is set up and feedback will only occur on the peaks of each comb. If you use multiple mics ... EACH mic tends to set up it's own frequencies. So when one of these comb peaks lines up with a peak in your system ... feedback!

 

A compressor will probably make the situation worse.

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