Home entertainment, acoustic audio or karaoke room commonly built in a small space of our house. So if we get cabling mistake, we get microphone feedback effect. Our speakers will clatter in little high volume control. It’s caused distance between microphone and speaker is too near. Sound of the speakers goes inside to microphone back. This called microphone feedback effect.

We have to know that every electronic equipment input or output has impedance. Impedance is a resistance value for AC signal in this case is audio signal.

When we plug or connect between two electronic equipments like a microphone and amplifier, ideally both of them have same impedance. If an amplifier has 600 ohm microphone impedance (see its manual)you have to purchase a microphone with 600 ohm impedance or less. This will make audio signal from microphone goes to amplifier without resistance.

Also for speakers, if amplifier has 8 ohm speaker output, the speaker should be 8 ohm too. If you use 4 ohm speaker, amplifier output will received twice bigger than 8 ohm speaker. This inequality of impedance cause standing wave between them and it make your audio system will clatter. And remember that microphone feedback effect can caused by mistake when we adjust microphone input and master volume control. To adjust it, we can start adjust microphone input control first. Adjust microphone input control to half of the range. Then start adjusts master volume control step by step up until your system clatter.

If your system has equality of impedance on each component you use, it will be a perfect system without microphone feedback effect.