Expert: Wayne Tapia - 7/11/2008

Question
Hi, I have a question about avoiding feedback squeal when using wireless mics. We recently added two wireless mics to our system and they produce a lot of squeal and I would like to know how to prevent it.  We have an outdoor area about the size of a basketball court with speakers set up at one end of the 'court' and the audience usually sits all over the court except the end with the speakers.  Sometimes the audience sites in a circle on the court with activities taking place in the center of the circle.  We use this area for our youth club activities; often with a music background we perform songs, skits, dramatic readings, etc. We also need to be able to walk among the audience with microphones.

The equipment we are using is:

1) Audio2000 AKJ7050 - Professional Karaoke Mixing Amplifier with Digital Key Controls & Echo (http://snurl.com/mixeramp)

2) Audio2000 AWM6112 - Plug-In-N-RechargeTM VHF Dual Channel Wireless Microphone System (http://snurl.com/a2kmics)

3) Audio2000 ASP5210 - Two 300W Full Range 10" 2-Way Loudspeakers (http://snurl.com/a2kspkrs)

Everything works fine with this equipment but recently a friend bought some Radio Shack wireless lapel mics (http://snurl.com/rsmics) and when we use the mics they produce a lot of squeal. We are unable to walk around where the audience is seated without the squeal.  I know we are in front of the speakers and that would normally be a problem but with the Audio2000 hand held wireless mics there is no squeal.

Do you have any suggestions?  We would like to avoid spending a lot of money for lapel mics (in the event you suggest replacing the ones we have).

Answer
Some suggestions -

Make sure when you are setting up a stage, you're not in front of the speakers - in other words, set the speakers at the front of the "stage". Another thing is that your handheld mics are a cardiod pickup pattern (mostly to the front of the mic), and the lapels are omni-directional (picks up from all directions equally). Cardiod mics are a bit better for feedback rejection in situations like yours.
If you have the capability and an engineer who knows his stuff, you may be able to make use of the mixing board EQ and locate the frequencies that are feeding back.