Today, we are going to talk about one of the most talked subjects but often misunderstood. This topic is about surround formats.
Surround system explained:
We have often heard jargons like 5.1 and 7.1 channels, we will now understand what these mean.
Stereophonic Sound
When the sound reproduction was invented, it was monophonic, which means a single source of sound. During the 1930's Cinemas were all monophonic, in which the sound actually doesn't follow the on screen actors.A British Engineer Alan Blumelin found this very disconcerting and told his wife that he had found a way to make the sound follow the on screen actors when they move across the screen. Thus Stereophonic sound was born.
A typical stereophonic system consists of two loudspeakers, essentially placed far enough for our ears to differentiate the sound from each individual speaker. The recording for such a format is also done using two microphones. So in effect a stereophonic sound is actually a recording consisting of two individual recordings, one for left and another for right. Technically these are called channels.
First thing one would notice in a stereo sound is that the sound is able to move between the speakers
The effect of such a playback would be like the instruments are laid out in front of you and the vocals are coming from in between the speakers. You will actually be able to pinpoint the instruments in the space between the speakers. This illusion is called a sound stage.
Stereo recordings are very popular and most of our modern CD's and MP3's are recorded in this format.
Surround Sound
Surround sound extends the effects provided by stereo sound to create an immersive sound field.
This is achieved by adding additional channels, called the surround channels. These surround channels surround the listener and create a 3-dimensional sound field.
Normal available surround sound channels are surround left and right; surround back or surround back left and surround back right. additionally surround height channels and front height channels are used to create an effect of height.
You would have already experienced this effect in a movie theater or a home theater system. Sounds moving around and panning behind you when the planes or helicopters shoot over the head.
Channels representation (2.1/5.1/7.1 etc)
Let us now dig deeper on how these channels are numbered
The number before the dot here represents the number of main speakers/channels in the configuration. The number after the dot represents the number of LFE channels.
Main Channels:
The Main speakers can be the Front Left, Center, Front Right, surround Left, Surround right, Surround back left, Surround back right etc.,
LFE channel:
LFE channels are for Low frequency Effects (LFE), which mainy deal with all the bass below 100Hz and in some cases extending below 20 Hz audible range. LFE channels are directly passed to the sub-woofers in your Home Theater setup. They contain nothing but the low rumbles like in the action scenes that can not only be heard but felt.
5.1 channel:
This is very common surround format and consists of Front Left, Center, Front Right, Surround left, Surround Right and one LFE channel.
This is normally available on DVDs and many Blu-rays, You need to have an Optical cable connector or a Coaxial connector (both form of SPDIF) or HDMi to be able to transfer 5.1 from a player to Amplifier. You can alternatively use 5.1 analog connections also in the form of 5 RCA plugs, but is rarely found in modern devices. Codecs normally used for 5.1 sound is Dolby Digital or DTS.
7.1 channel
This is an extension of 5.1 channel and consists of two extra back surround channels ie., Surround Back left and Surround back right.
To enjoy true 7.1, an Amplifier should be able to receive audio over HDMI. 7.1 Audio is usually found on some Blu-rays and the codecs that support this format are Dolby TrueHD, Dolby Digital Plus and DTS-HD Master Audio.
There are many more configurations available, but above are most popular.
Often, the bass from the main channels are redirected to the subwoofer along with the LFE, thereby relieving the main channels from the heavy bass. This has two advantages, the main speakers tend to distort less and the main speakers can be smaller. Hence in most modern HTiB (Home Theater in a Box) solutions you find the main speakers to be small satellites.
Well, how good a solution this is - is a debatable topic, because the smallish satellites never produce the deep vocals and crisp Mids that are expected while listening music and the dialogues.
Note: We will learn about codecs (Dolby/DTS etc.,) more in the coming articles.
Surround system explained:
We have often heard jargons like 5.1 and 7.1 channels, we will now understand what these mean.
Stereophonic Sound
When the sound reproduction was invented, it was monophonic, which means a single source of sound. During the 1930's Cinemas were all monophonic, in which the sound actually doesn't follow the on screen actors.A British Engineer Alan Blumelin found this very disconcerting and told his wife that he had found a way to make the sound follow the on screen actors when they move across the screen. Thus Stereophonic sound was born.
A typical stereophonic system consists of two loudspeakers, essentially placed far enough for our ears to differentiate the sound from each individual speaker. The recording for such a format is also done using two microphones. So in effect a stereophonic sound is actually a recording consisting of two individual recordings, one for left and another for right. Technically these are called channels.
First thing one would notice in a stereo sound is that the sound is able to move between the speakers
The effect of such a playback would be like the instruments are laid out in front of you and the vocals are coming from in between the speakers. You will actually be able to pinpoint the instruments in the space between the speakers. This illusion is called a sound stage.
Stereo recordings are very popular and most of our modern CD's and MP3's are recorded in this format.
Surround Sound
Surround sound extends the effects provided by stereo sound to create an immersive sound field.
This is achieved by adding additional channels, called the surround channels. These surround channels surround the listener and create a 3-dimensional sound field.
Normal available surround sound channels are surround left and right; surround back or surround back left and surround back right. additionally surround height channels and front height channels are used to create an effect of height.
You would have already experienced this effect in a movie theater or a home theater system. Sounds moving around and panning behind you when the planes or helicopters shoot over the head.
Channels representation (2.1/5.1/7.1 etc)
Let us now dig deeper on how these channels are numbered
The number before the dot here represents the number of main speakers/channels in the configuration. The number after the dot represents the number of LFE channels.
Main Channels:
The Main speakers can be the Front Left, Center, Front Right, surround Left, Surround right, Surround back left, Surround back right etc.,
LFE channel:
LFE channels are for Low frequency Effects (LFE), which mainy deal with all the bass below 100Hz and in some cases extending below 20 Hz audible range. LFE channels are directly passed to the sub-woofers in your Home Theater setup. They contain nothing but the low rumbles like in the action scenes that can not only be heard but felt.
5.1 channel:
This is very common surround format and consists of Front Left, Center, Front Right, Surround left, Surround Right and one LFE channel.
This is normally available on DVDs and many Blu-rays, You need to have an Optical cable connector or a Coaxial connector (both form of SPDIF) or HDMi to be able to transfer 5.1 from a player to Amplifier. You can alternatively use 5.1 analog connections also in the form of 5 RCA plugs, but is rarely found in modern devices. Codecs normally used for 5.1 sound is Dolby Digital or DTS.
7.1 channel
This is an extension of 5.1 channel and consists of two extra back surround channels ie., Surround Back left and Surround back right.
To enjoy true 7.1, an Amplifier should be able to receive audio over HDMI. 7.1 Audio is usually found on some Blu-rays and the codecs that support this format are Dolby TrueHD, Dolby Digital Plus and DTS-HD Master Audio.
There are many more configurations available, but above are most popular.
Often, the bass from the main channels are redirected to the subwoofer along with the LFE, thereby relieving the main channels from the heavy bass. This has two advantages, the main speakers tend to distort less and the main speakers can be smaller. Hence in most modern HTiB (Home Theater in a Box) solutions you find the main speakers to be small satellites.
Well, how good a solution this is - is a debatable topic, because the smallish satellites never produce the deep vocals and crisp Mids that are expected while listening music and the dialogues.
Note: We will learn about codecs (Dolby/DTS etc.,) more in the coming articles.
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