Karaoke Forums

Here is my basic audio setup:

Nady DKW Duo Wireless Mics
Alesis Multimix USB 8 (into computer)
Behringer Eurolive B215A Active 2-Way Loudspeaker Pair

My problem is I am getting a hum and squeal or some sort of feedback from my mics. It does not happen every time the mics are used but It does happen often.
Could the gain setting on the mixer be causing this? I have the gain turned up about 3/4 of the way. If I turn it down the mics volume is low even with the main mic volume turned all of the way up. There is also a "Phantom Power" switch on my mixer, not to sure about what this is for. Thanks in advance for any advice.

Thanks,
downboy2005

Where are your speakers located in relation to the microphones?

Are they out to the sides and in front of the stage or are they behind the singers? What size rooms do you usually get the problem in?

Are the speakers on stands or mounted up high above people?

Next time you get the same problem, try unplugging the cordless mics and plugging in only a corded mic or mics. If the problem goes away, you may have some interference in your cordless frequency. Depending on your cordless frequency and location, this can vary. Sometimes cordless mics get more interference when their batteries are getting low as well. Make sure your batteries have a decent charge for each show.

If you are using dynamic mics, you do not need to turn on phantom power. That is only needed if you are using powered condenser mics or other devices that need inline power.

Suggest you try using a reasonable wired mic (SM58, or if you want cheap the Behringer XM8500) and see if you have the same issues. Those aren't very good mics, and they will have much less gain before feedback than better mics.

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[color=#ffff55]Mickey J.[/color]
Alas for those who never sing, but die with all their music in them.
-- Oliver Wendell Holmes, Sr.

They are not very good mics, which is your first problem. They are going to give you more feedback issues than higher-quality mics would. Turning down the gain a bit more and turning up the mic channel volume will help somewhat.

I would say the main culprit of feedback is usually speaker placement. You may be able to solve your problem just by rearranging your setup. A feedback loop is simply when your mic can "hear" the sound from your speakers and sends them back into the amplifier to create a continuous, infinite loop of re-amplified sound.

It is the same effect as when you have a video camera hooked up a TV and videotape the picture on the TV. The video camera is taking in the same picture it is producing, resulting in a continuous loop of video feedback (where you see the video signal over and over again into infinity).

SO, the simple solution to feedback is to have a correct spacial relation between your mics and speakers so that your mics can't pick up the sound of your speakers. Most good mics will have a pickup pattern so that they do not pick up sound from the bottom part of the mic grille, which makes it so you can point the bottom of a mic directly at a speaker and the mic won't pick up most of the sound. This is why vocal monitor speakers are placed on the ground at the same angle as the microphones. Just like with the video feedback, if you don't point the part that takes in the signal (the lens/the top of the microphone) at the end output (the TV/speakers), then you don't get the feedback!!

SO, if you have two main speakers in your room, you should make sure that they don't point towards the top 60% of your mic. Sing BEHIND or even BETWEEN your main speakers and you will probably fix your feedback problem.

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C Mc
KJ, FL

THANKS!! I really appreciate all of the replies. I have attached very simple diagram of my normal setup. I am usually in a corner with the video display to my right and the singers are out front. I realize this is not the best scenario but I usually only do smaller
rooms. Also my speakers are on stands, approx. 5 ft high at the base of the speaker.
Again, thanks for all of the responses.

Thanks,
downboy2005

Don't understand your set up? You have a table between the speakers? Is that your booth? Where are the customers in relation to this?

Interesting about your gain. I can NEVER turn mine up to 75% without creating some type of feedback issue.

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KingBing Entertainment C'mon Up! I have a song for you!!! [font=MS Sans Serif][/font]

There would be a wall behind the table with just enough room for me to maneuver.
The crowd would be to the singer side (behind the singers). It faces the singer to the display and away from the crowd (not a normal stage setup) but it works for the small parties I do. I do not do clubs or bars so this is not a normal setup. Thanks for the reply.

downboy2005

It is going to be very difficult to control feedback as long as your singers are directly in front of your main speakers.

I don't know where in your room you can put them, but again, as long as the microphones can "hear" the output from the main speakers, you have a feedback loop. You'll need to either reposition the singers or the speakers so the mics don't pick up the sound from the main speakers.

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C Mc
KJ, FL

Thanks TopherM, I will look at other position possibilities.

downboy2005