Audio Basics

Audio Basics

Technical Stuff

  • Microphones only produce analog signals.
  • Speakers can only accept (use) analog signals.
  • Each speaker is considered a channel and needs its own audio amplifier.
  • Stereo is 2 channels – no more no less.
  • Surround Sound (4, 5, 7, or 9 channels) is accomplished using computers. The computers analyze the sound; break it up into channels and digitize (encode) it.
  • All Surround Sound is stored in a digital format.
  • There are many digital formats (Dolby Pro Logic, Dolby Digital, DTS, THX Surround, etc. to name a few) Each digital format requires its own special encoder and decoder.

Digital signals must go through a computer to convert (decode) the digital signal into the analog signals that speakers require.
Scenario – a house with:

  • Family Room has the electronics (TV, Set-top-box, DVD Player,
  • Home Theater Receiver (HTR), Audio Amps, etc.) and is set up with 5 speakers: left front, center, right front, left rear, right rear
  • Kitchen with two speakers
  • Living Room with two speakers
  • Outdoor Patio with two speakers

The Family Room can handle Surround Sound, the other three rooms only stereo sound. That is a total of 11 channels of audio potentially requiring 11 audio amplifiers and the means to decode a digital signal into both 5 channel surround (for the Family Room) and 2 channel stereo (for the other 3 rooms).

Questions about the Kitchen, Living Room and Outdoor Patio:

  • Must each Room have the ability to play its own (different) music/program?
  • Must the sound volume be adjustable separately for each room?
  • Must the sound be able to be turned on and off separately for each room?

The answers will determine what features you will need to look for in a Home Theater Reciever. Most likely you will need both a HTR and one or more Audio Amplifiers.


  • Audio amplifiers can be packaged (like a six pack of beer) into a single unit.
  • Most HTRs can take analog stereo and simulate (i.e. fake) surround sound by passing the analog stereo signal through a special Digital Signal Processor (DSP). Typical simulated surround sound modes are 5CH/7CH stereo, Matrix, and Neural. These simulated surround sound modes are NOT the Dolby, DTS, THX digital formats mentioned above however.