Input devices put audio signals into your sound system. One common method of inputting audio signals into a system is using equipment such as microphones, instruments, and various types of audio equipment. Quality microphones are expensive but they give you the best vocal tone quality, and less feedback (squeal)  from the speakers.Get the best Mic you can afford, this is not the place to skimp because the best sound system in the world can’t make a poor quality signal sound good. Professional recording engineers test dozens of mics with a singer before they record, because not every mic fits every singer; they have to find the one that is ‘just right’.

Placement of microphones in relation to the source of the sound (the singer’s face, an amplifier speaker or a piano) is also important, but even that can’t compensate for a poor quality microphone. The direction from which the microphone picks up sound, is called the polar pattern; In other words, a microphone is designed to receive sound from one direction; you don’t speak into the side of the mic, you speak straight in to the tip. They are made this way to avoid the mic picking up other sounds from around you. Also, by keeping it pointed always away from a speaker, it never picks up the speaker output, thus avoiding those deafening, high-decibel feedback squeals. I will write other articles about some of these subjects later in more detail.


VERY IMPORTANT:

You must know how to set the mixer input level of your instruments and microphones, if you expect to have powerful sound without fighting feedback. Set the levels, one channel at a time until you complete all channels being used. 

You should be able to find step-by-step instructions in the user manual for your mixer, since that’s what the mics are connected to. A mixer is a device that has a separate channel for every input signal (every voice, every instrument) and mixes it all into one signal to send to the speakers. Each channel has a sliding volume control, called a fader. That way, the volume of each signal can be individually controlled, and if a volume adjustment needs to be done during live performance, the ‘mixer dude‘ can make smooth, FADED adjustments, instead of sudden, jerky, noticeable ones. The Master Fader, is usually on the lower-left, and controls volume for the entire system, after the signals are mixed. It turns down EVERYTHING at once, proportionately.

To set a mic/instrument input level:
Set the channel’s fader to “U”, and the Master Fader to “U”. Now press the SOLO button on that channel. (You don’t need amps or speakers to do this.) Feed signal into the mixer channel input, just as it will be used, i.e., sing into a mic, or play, or preach, whatever you’re using that channel for, at the volume (loudness) that will normally be used.  The lights or level indicators on the mixer will show you the signal level. Use the “INPUT GAIN” knob for the channel you are setting – (usually the top/ first knob on the mixer, for that channel) – to set the level. Raise it until the level indicator reads around zero Db consistently. Set every channel that you plan to use, as they’ll be used. All EQ and AUX knobs should be set to zero and later adjusted as needed (these are usually blue and red).

Cables

Cables carry signals to and from devices, from the microphone to the mixer, and from the mixer to amplifiers, or from other equipment. If it is from non-microphone type devices, this type of input is called line-level input, meaning the signal is much stronger than signals from microphones. Consult owner’s manuals to ensure compatibility of devices.

Many guitar and keyboard amps have a line-level output to send signal directly into the mixer. Professionals agree that miking the amps produces better tone than playing directly into the mixer, especially when recording. This means, you set the microphone in a mic stand, in front of the amplifier speaker to input the sound to the mixer. Put the mic right against the fabric on the amp face, but a little off to the side rather than directly in front of the speaker as that could damage the mic. Place it at about a 30 degree angle.