Surround Sound

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.

What is High End Audio?

Ever wondered what is actually high end? what differentiates it from most of the commercial stuff available in the market?
Well, Most of the high end stuff are expensive - many times than their commercial counterparts. It makes many believe that its just waste of money to buy stuff that expensive.
It depends on what your passions are.
I asked my friend once, which one would you go for: a 20 Mega-Pixel point and shoot or a 12 Megapixel DSLR. The answer was instantaneous - Point and shoot.

Well, the truth is he is not passionate about photography and needs a regular clicker. Does not want to invest a huge sum on cameras, and the marketing tags like megapixels mean a lot to him.

Audio is something very similar, Only if you are very passionate, then it would make sense in investing a lot otherwise you are either showing off or just believe expensive is better.

Is expensive always better?
It's a debatable question. Since Audio and quality is such a subjective field, it always leads to a great flame wars on which is better.

There is this American designer "Bob Carver" who created a stir in the audio industry in the 1980 and proved that Expensive is not always better.

Bob had challenged some very well known High End audio magazines that he can duplicate the sound of any amplifier at any price.
Two magazines had accepted his challenge.

First was the Audio Critic,  asked him to copy the sound of Mark Levinson ML-2, then highly regarded amp and Bob was able to acoustically duplicate it's sound and sold the amp he made as M1.5t

Second was the Stereophile magazine and gave him an amp whose name was kept secret (Conrad-Johnson Premier Five) from Bob.
The challenge was to copy the sound in 48hrs without opening the amp.
The original amp was around $12,000+
Bob accepted the challenge and promptly copied the sound as agreed, only that his amp just costed $400.
In fact their sounds were so similar that the employees of the Stereophile magazine themselves were not able to make out which was the original amplifier.

What he did was simply  copy the transfer function of the amp. He used two different amps with the same identical source and out of phase and tuned the second amp using distortion pots.

This brings the question, how should an amplifier sound?
Technically, it's easy, an amplifier should not have any sound of its own. The ouput should be exact same wave as the input only amplified.
This is rarely the case in practice. all amplifiers will introduce noise or distortion as we call it. and this has to be in acceptable limits.
But there are other things too... How should it handle the lows and highs?
all of these stuff are very subjective and depends on personal taste.

A very good example is the Valve or a Tube amplifier. These old and ancient amplifiers have a huge distortion introduced in the amplification stage. Supposedly these are pleasing on the ears and many prefer the sound of the tube amp. I am not denying that these amps are not faithful but are highly regarded by some. Others disagree.

These debates go on forever. Transistor vs Tubes vs Class-D amplifiers.
It's all subjective so I intend to make no personal choice.

However, I would like share a personal experience. I found an el-cheapo Chinese amplifier on Amazon - The Lepai LP-2020A+ Amplifier, which costs only $20 and has a chip that shook the audiophile industry - The Tripath TA2020 Chip. This chip supposedly uses Class D amplification and delta sigma modulation. Result is crisp and clear sound. I am comparing the sound with my more expensive receiver from Marantz which costs 10 times more and found the Chinese amplifier sound better.
This amplifier is no bigger than a  soap box, but the sound it produces is just awesome.
Try it if you get your hands on this.

Introduction:
 
After more than 10 years on Internet and working for the IT Industry, I now somehow got an itch to create a blog of my own. Never had any interest earlier.

First, A bit about myself:
My name is Arunkumar; I live in Bangalore, working for a multinational in the Virtualization space.
My passion since childhood has always been audio and audio equipment like the speakers, amplifers, decoders etc.,
Speakers always fascinated me, even as a child I was impulsively attracted towards them.
I would like to call myself an audiophile, but I lack the so called golden ears.

So I have started this blog to share my ramblings on the subjects of audio and the audiophile industry, equipment etc.,