Tips for Karaoke in the Home
One of our customers emailed me last week to ask me how to fix feedback problems, so I’ve written this article to explain what feedback is and how to remove feedback during a performance!
What Is Feedback?
Feedback is that awful squeal or howl that happens when a microphone gets too close to the speakers. It is caused when a sound coming out of the speakers is picked up by the microphone, gets amplified and then sent back out of the speakers only to be picked up by the microphone again, amplified and sent back out of the speakers in a never ending loop.
Speaker Placement
Make sure your microphone is not pointed towards your speakers.
A room with a lot of reflective surfaces will bounce the sound around and may cause the addition of certain frequencies that could result in feedback. In this situation, equalization works best. Even adding carpet to the walls and floors will help.
Microphone Type
Uni-directional microphone types work best in live music. They don’t pick up sound from the sides and back of the microphone. Be sure though, that the singer uses the microphone correctly keeping the mouth close to the front of the microphone.
Multi-Microphone Systems
If there is more than one microphone be sure to turn off each one that is not being used. Problems may sometimes arise if there is more than one person singing at the same time, and one of the singers, while not singing, will allow the microphone to move close to the speakers. This is a very awkward situation and the best solution would be an automatic microphone mixer that will activate the microphone when used.
EQ
Lower the offending frequencies with equalization.
First we must identify which frequency is being fed back into the microphone, then lower that particular frequency.
Get someone to speak into your microphone while slowly increasing the volume until you just start to hear the feedback. This is the frequency that must be decreased. Experiment by lowering different equalizer bands until you identify what frequency is causing the feedback. Once this band is lowered you should be able to even raise the music a little more without the fear of feedback.
Types Of EQ
To be able to eliminate feedback with equalization, simple treble/bass controls will not work well. We must use either a parametric or graphic equalizer. Each has advantages or disadvantages.
A parametric equalizer allows us to tune in to a specific frequency and then either boost or reduce it. A graphic equalizer, on the other hand, can modify a number of preset frequencies. For example, you found that a feedback loop was being generated at 5kHz. Since your graphic equalizer can only modify certain frequencies, say the 4kHz and 6kHz bands, you could lower 4zHz and 6kHz bands to reduce the feedback. However, not only will the offending frequency be reduced but also the rest of the sound would be greatly affected along with it. As far as graphic equalizer goes, a 30 band graphic (1/3-octave) equalizer unit will provide the most flexibility in reducing feedback and fine tuning your sound, but a parametric equalizer will be far more effective in reducing your unwanted feedback.
Sound Installations
If your karaoke sound system is permanently installed or will not be moved for quite a while, you should use a Spectrum Analyzer to adjust the equalization of your system to the room. You’ll be able to remove unwanted frequencies that can lead to feedback and bring out certain frequencies that might otherwise have been lost. These units are usually quite expensive so check with your local music stores to see if you can rent one for an evening.
Feedback Reducing Units
There are a few dedicated hardware units designed to reduce or eliminate feedback. These units may or may not work correctly depending on the system and room. But in general they will reduce more than is necessary.
Until next time, get up and SING!
Dr. Karaoke