Multi-chanel Sound System

The descriptions of surround sound specifications below distinguish between the number of discrete channels encoded in the original signal and the number of channels reproduced for playback. The number of channels reproduced for playback can be changed by using matrix decoding. A distinction is also made between the number of channels reproduced for playback and the number of speakers used to reproduce (each channel may refer to a group of speakers). The graphics to the right of each specification description represent the number of channels, not the number of speakers.

4.0 Channel Surround (analog matrixed: Dolby Pro Logic)

Extracts 4 audio channels from a specially encoded two-channel source:- Two channels for speakers at the front - left (L) and right (R).- One channel for both surround speakers at the rear - mono surround channel (S).Describes the Dolby Pro Logic matrixed surround system. Source media, usually VHS, Laser Disc or television broadcast, CableTV/Satellite is often branded with "Dolby Surround" logo. This is the encoding used on the analog optical track for theatrical motion picture films.Speaker placement: (4 channels in total) The front speakers should be placed at the edges of the screen, toed in to face the central listening location, and the tweeters should be ear height. The center speaker should be placed behind the screen (when using projection) or over or under a TV, and as close to ear-high as possible. Surround channel speakers should be placed high on side walls, slightly behind the listening position, and should be of bi-pole construction.

5.1 Channel Surround (analog matrixed: Dolby Pro Logic II)

Extracts 5 audio channels from either a specially encoded two-channel or a stereo source:Two channels for speakers at the front - left (L) and right (R).One channel for speaker at the center - center (C).Two channels for surround speakers at the rear - surround left (LS) and surround right (RS).One low-frequency effects channel (LFE).Describes the Dolby Pro Logic II matrixed surround system. Source media is often branded with "Pro Logic II" logo.Surround sound speaker placement: (6 speaker channels in total) surround sound speaker placement is different for both music and movie content.For music, speakers should be placed closest to the left and right of the listening position, close to that of the 6.1 surround speakers.For movie surround, the front speakers should be placed at the edges of the screen, toed in to face the central listening location, and the tweeters should be ear height. The center speaker should be placed behind the screen (when using projection) or over or under a TV, and as close to ear height as possible. Rear channel speakers should be placed high on side walls, slightly behind the listening position, and should have a normal high-quality monopolar construction.

5.1 Channel Surround (digital discrete: Dolby Digital, DTS, SDDS)

Delivers 5 discrete audio channels and 1 LFE channel from a 6 channel source:Two channels for speakers at the front - left (L) and right (R).One channel for speaker at the center - center (C).Two channels for surround speakers at the rear - surround left (LS) and surround right (RS).One low-frequency effects channel (LFE).Describes the Dolby Digital, Digital Theater System (DTS), and Sony Dynamic Digital Sound (SDDS) systems. Source media, usually DVD and sometimes Laser Disc or satellite/digital cable is often branded with "Dolby Digital" and/or DTS logos.DTS uses a higher sampling rate than Dolby Digital, thus DTS uses less compression and achieves higher fidelity than Dolby Digital.Surround Sound speaker placement: (6 speaker channels in total) Surround Sound speaker placement is different for both music and movie content.For music, speakers are placed in a circle around the listener. The center channel has 0º offset, left and right are offset ± 30º, and the left/right surrounds are offset by ±110º. Also all speakers should be monopole, equidistant to the listener, and all delay (ms) calculations on the surround decoder should be turned off (0 ms).For movie surround, the front speakers should be placed at the edges of the screen, toed in to face the central listening location, and the tweeters should be ear height. The center speaker should be placed behind the screen (when using projection) or over or under a TV, and as close to ear height as possible. Rear channel speakers should be placed high on side walls, slightly behind the listening position, and should have a normal high-quality monopolar construction.

6.1 Channel Surround (analog matrixed: Dolby Pro Logic IIx)

Extracts 6 audio channels and 1 low-frequency channel from either a specially encoded two-channel or a stereo source:Two channels for speakers at the front - left (L) and right (R).One channel for speaker at the center - center (C).Two channels for surround speakers at the sides - side left (LS) and side right (RS).One channel for surround speakers at the rear - back surround channel (BS).One low-frequency channel to drive a sub-woofer.Describes the Dolby Pro Logic IIx matrixed surround system. Source media is the same as both Dolby Pro Logic and Dolby Pro Logic II.Surround Sound speaker placement: (7 speakers in total) surround sound speaker placement is different for both music and movie content.For music, speakers placement is best as shown in the diagram, tweeters should be pointed closest to the listening position.For movie surround, the front speakers should be placed at the edges of the screen, toed in to face the central listening location, and the tweeters should be ear height. The center speaker should be placed behind the screen (when using projection) or over or under a TV, and as close to ear height as possible. Side channel speakers should be placed high on side walls, to the left and right of the listening position, equidistant from the front speakers and the rear speakers. Rear channel speakers should be placed high on side walls, slightly behind the listening position, and should have a normal high-quality monopolar construction.

6.1 Channel Surround (digital partially discrete: Dolby Digital EX)

Delivers 5 audio channels, 1 extracted audio channel and 1 LFE channel from a 6 channel source:Two discrete channels for speakers at the front - left (L) and right (R).One discrete channel for speaker at the center - center (C).Two channels for surround speakers at the sides - left surround (LS) and right surround (RS). The discrete LS and RS channels are dematrixed into LS, RS, and back surround (BS).One channel for surround speakers at the rear - back surround channel (BS).One low-frequency effects channel (LFE).Describes the Dolby Digital EX discrete/matrixed hybrid Surround system. Source media, usually DVD is often branded with "Dolby Digital EX" logo. This format is used in some theatrical motion picture films.Surround Sound speaker placement: (7 speaker channels in total) Surround Sound speaker placement is different for both music and movie content.For music, speaker placement is unknownFor movie surround, the front speakers should be placed at the edges of the screen, toed in to face the central listening location, and the tweeters should be ear height. The center speaker should be placed behind the screen (when using projection) or over or under a TV, and as close to ear height as possible. Side channel speakers should be placed high on side walls, to the left and right of the listening position, equidistant from the front speakers and the rear speakers. Rear channel speakers should be placed high on side walls, slightly behind the listening position, and should have a normal high-quality monopolar construction.

6.1 Channel Surround (digital discrete: DTS-ES)

Delivers 6 discrete audio channels and 1 LFE channel from a 7 channel source:Two channels for speakers at the front - left (L) and right (R).One channel for speaker at the center - center (C).Two channels for surround speakers at the sides - side left (LS) and side right (RS).One channel for surround speakers at the rear - back surround channel (BS).One low-frequency effects channel (LFE).Describes the DTS ES discrete Surround system. Source media, usually DVD is often branded with "DTS ES" logo. In theatrical motion picture film, this format does not exist, and the name "DTS-ES" refers to the above hybrid format used for Dolby Digital EX.Surround Sound speaker placement: (7 speaker channels in total) Surround Sound speaker placement is different for both music and movie content.For music, speakers placement is unknownFor movie surround, the front speakers should be placed at the edges of the screen, toed in to face the central listening location, and the tweeters should be ear height. The center speaker should be placed behind the screen (when using projection) or over or under a TV, and as close to ear height as possible. Side channel speakers should be placed high on side walls, to the left and right of the listening position, equidistant from the front speakers and the rear speakers. Rear channel speakers should be placed high on side walls, slightly behind the listening position, and should have a normal high-quality monopolar construction.

7.1 Channel Surround (digital discrete: Dolby Digital Plus, DTS-HD, Dolby Digital True HD)

Delivers 7 audio channels and 1 LFE channel from an 8 channel source:Two channels for speakers at the front - left (LF) and right (RF).One channel for speaker at the center - center (C).Two channels for surround speakers at the sides[citation needed] - side left (L) and side right (R).Two channels for surround speakers at the rear - surround left (LS) and surround right (RS).One low-frequency effects channel (LFE).Describes the Dolby Digital Plus discrete Surround system. Source media, usually HD DVD and sometimes Blu-Ray is often branded with "Dolby Digital Plus" and/or "DTS-HD" logos.Surround Sound speaker placement: (8 speaker channels in total) Surround Sound speaker placement is different for both music and movie content.For music, speaker placement is unknown.For movie surround, the front speakers should be placed at the edges of the screen, toed in to face the central listening location, and the tweeters should be ear height. The center speaker should be placed behind the screen (when using projection) or over or under a TV, and as close to ear height as possible. Side channel speakers should be placed high on side walls, to the left and right of the listening position, equidistant from the front speakers and the rear speakers. Rear channel speakers should be placed high on side walls, slightly behind the listening position, and should have a normal high-quality monopolar construction.

Stereo Sound

Stereo Sound

True stereophonic sound systems have two independent audio signal channels, and the signals that are reproduced have a specific level and phase relationship to each other so that when played back through a suitable reproduction system, there will be an apparent image of the original sound source. Stereo would be a requirement if there is a need to replicate the aural perspective and localization of instruments on a stage or platform, a very common requirement in performing arts centres. This also means that a mono signal that is panned somewhere between the two channels does not have the requisite phase information to be a true stereophonic signal, although there can be a level difference between the two channels that simulates a position difference, this is a simulation only. That's a discussion that could warrant a couple of web pages all by itself. An additional requirement of the stereo playback system is that the entire listening area must have equal coverage of both the left and right channels, at essentially equal levels. This is why your home stereo system has a "sweet spot" between the two loudspeakers, where the level differences and arrival time differences are small enough that the stereo image and localization are both maintained. This sweet spot is limited to a fairly small area between the two loudspeakers and when a listener is outside that area, the image collapses and only one or the other channel is heard. Living with this sweet spot in your living room may be OK, since you can put your couch there, but in a larger venue, like a church sanctuary or theatre auditorium, that sweet spot might only include 1/3 the audience, leaving 2/3 of the audience wondering why they only hear half the program. In addition a stereo playback system must have the correct absolute phase response input to output for both channels. This means that a signal with a positive pressure waveform at the input to the system must have the same positive pressure waveform at the output of the system. So a drum, for instance, when struck produces a positive pressure waveform at the microphone and should produce a positive pressure waveform in the listening room.

Mono Sound

Mono sound


Mono or monophonic describes a system where all the audio signals are mixed together and routed through a single audio channel. Mono systems can have multiple loudspeakers, and even multiple widely separated loudspeakers. The key is that the signal contains no level and arrival time/phase information that would replicate or simulate directional cues. Common types of mono systems include single channel centre clusters, mono split cluster systems, and distributed loudspeaker systems with and without architectural delays. Mono systems can still be full-bandwidth and full-fidelity and are able to reinforce both voice and music effectively. The big advantage to mono is that everyone hears the very same signal, and, in properly designed systems, all listeners would hear the system at essentially the same sound level. This makes well-designed mono systems very well suited for speech reinforcement as they can provide excellent speech intelligibility.

Sound System

Sound

Sound is generally known as vibrational transmission of mechanical energy that propagates through matter as a wave (through fluids as a compression wave, and through solids as both compression and shear waves) that is audibly perceived by a living organism through its sense of hearing.