Realistic Surround Audio For Home Audio-Video System

    Providing a good audio set up is an important step towards setting up a home cinema audio-video system, which include selection of appropriate amplifier and loudspeakers. Choosing an expensive system is not the key to an effective audio setup, but it is the proper scientific arrangment of components which is crucial.

 

    In case of amplifiers, we have to decide whether we need two channel stereo sound or surround set up. Surround sound supports built-in decoding of Dolby and DTS system. Amplifiers with 50W r.m.s per channel is enough for domestic purpose. The important thing to be noticed is that amplifier selected should have atleast two HDMI inputs and two HDMI outputs ( HDMI - High Definition Multimedia Interface - default connection between audio and video equipment ). Though, inbuilt amplifiers and loudspeakers are available, external amplifier which support multiple loudspeakers are used ( surround set up).

    Stereo sound use two loudspeakers, one to the left and one to the right, infront of the listener. Two loudspeakers with same signal, at different volumes can produce sound, coming from any point between the two loudspeakers. If both the loudspeakers have same volume, the sound source appears to be in the centre. If right signal is louder, sound source move towards right and vice-versa.

    In surround set up, this principle is extended by using multiple speakers. We use five loudspeakers, and one bass reflex sub-woofer referred to as 5.1. According to principle of acoustics, as the frequency falls, the sense for direction of sound diminishes, so a single loudspeaker can provide bass frequency. It is the bass frequency which need largest and powerful loudspeaker, while upper and middle frequencies need only smallest loudspeakers. 

Two loudspeakers at the front provide left and right sound infront of the listener. The two rear loudspeakers in combination with front loudspeakers provides sound behind the listener. To strengthen the dialogues in close-up shots, a central loudspeaker is used behind or just above the middle of the screen.

(The speakers attached to wall of room indicates more pragmatic but less effective positions)

    5.1 layout has difficulty in placing two rear speakers in case of domestic system, because ideal position is just behind and above the listener.

 

    A single bass loudspeaker can be placed anywhere in the room, and appropriate place can be found, using trial and error method. The ideal position may be between two front loudspeakers.

    Smaller 5.1 systems eliminate the need for separate amplifier, by incorporating five channel amplifier into sub-woofer cabinet.