Welcome back. Finished running all the cables and wires to your sound system yet? Now it’s time to go over the software to drive your multichannel system. We’ll start off with the basics then move to what is in store for the future.
This is simply your good old stereo sound. Two discrete channels feeding two speakers. Almost everything is in stereo, including most television programs, FM radio, some AM radio, and most of the better audio and video clips on the internet. We really take stereo for granted now, but it is a marked improvement over mono sound, that is a single channel signal.
kinda boring, huh?
Physically, this would be a pair of speakers and a subwoofer. In most cases, you can use a stereo, two-channel signal to drive this setup. When doing this, the receiver or the speaker’s internal crossovers determine what sound goes to the subwoofer. This separation of the channels was not done by the mixing engineer. The only way you can get a discrete subwoofer signal with this setup is with Multichannel Super Audio CD, DTS audio, DVD audio, or Dolby Digital signals downsampled to 2.1 audio. There are a few sources that are written specifically for 2.1 audio, but you will need to have the decoding hardware necessary for at least 5.1 audio to use 2.1 audio. Basically, if you have the equipment to support 2.1 audio with a discrete subwoofer channel, you have the equipment needed for a 5.1 system.
Gotta have my subs
The first taste of surround sound at home came with Dolby Surround Sound. This took a two channel stereo signal and created sound that went to four speakers. The pair of rear speakers, however, received a mono signal. So basically, the decoder was taking a two channel source and creating a third channel for the rear by analyzing the phase differences between the stereo signals. With this first generation surround sound, the rear speakers were limited to a frequency response of about 100hz to 7 khz, This limited frequency range helped to limit localization of the rear channels to prevent it from sounding too artificial. Many years ago, quadraphonic systems powered by LP’s and 8-tack machines were available, but the high buy-in cost of this technology did not allow it to catch on with the general population. These systems are now considered collectibles. Subwoofers were often used with smaller satellite speakers, but the signal was derived from the front channels.
Starting to get a little interesting…