To move your audio signal around within your home recording sound mixer, first you need to get the signal into the system via inputs and then adjust the signal level. You perform these steps with the input jacks and the trim control.

You find the following three basic types of inputs, which are generally located in the back of your system:

  • Microphone: This is the XLR input (the three-pin thingy). It’s used for microphones and often also has phantom power as part of its connection (which generally can be turned off if you want). Phantom power is necessary for condenser mics to function.

  • Line/instrument: This is a 1/4-inch jack (generally TS but sometimes TRS-balanced) that accepts line-level signals from a synthesizer, a drum machine, or the line output from your guitar amp.

  • Hi-Z: This is an input designed for the home recordist. This type of input uses a mono 1/4-inch (TS) jack and allows you to plug your electric guitar (or bass or fiddle — anything with an electronic pickup) directly into your system without having to mic it or run it through a direct box first.

A direct box (or DI box, short for direct injection) is traditionally used to connect your guitar or bass directly to the mixer without having to run it through your amp first. A direct box’s purpose is twofold:

  • To change the guitar’s impedance level so that the mixer can create the best sound possible (otherwise the guitar can sound thin or noisy)

  • To change the cord from unbalanced 1/4-inch to balanced XLR so that you can use a long cord without creating noise

If you use a computer-based system, the inputs and outputs are located in your audio interface — the hardware you use to connect the analog world to the computer world.