A – Microphone – We are going to assume that we are using a microphone for recording an audio signal, but this could be a keyboard, drum machine, turntable, or any other audio signal.

B – Analog Signal – Yes, this wavy thing is supposed to look like a Sine Wave. It represents the signal that is passing through the mic cable and heading into your soundcard.

C – Soundcard – This is a breakout box of a high quality home recording soundcard. It is always recommended that you use a soundcard with a breakout box. Inside this soundcard, the preamps boost the analog signal from the microphone up to a signal the soundcard can use. This boosted signal is called “line – level”.

It's usually fairly straightforward to test this portion of the audio chain. Most soundcards have a LED lights that light up as the signal coming into the soundcard increases. So screaming into the microphone will light up more LED lights than whispering would.

Also within the soundcard is the analog to digital conversion. This means the analog wave you saw in B is converted to ones and zeros.

Graphic provided by DT_Chris from  http://www.darktownstudios.com

D – Digital Signal – As mentioned above, the signal leaving the soundcard is digital. This means it is ones and zeros. Your computer stores this digital information on the hard drive. It's important to note that the cables passing this digital signal are either USB, USB 2.0, Firewire, or some sort of cable that looks like a printer cable. This is the cable that connects your soundcard to your computer.