How loud can my speakers play?
First of all, speakers can play no louder than your amplifier's ability to deliver undistorted power. When overdriven, most amplifiers distort the sound in a way that can damage any speaker.
Within the power limitations of your amplifier, the safe volume level depends on the length of lime that the speakers play at a given level. Heat is an unavoidable by-product of the process by which dynamic drivers (the part of a speaker that produces the vibration) produce sound. Modern speakers use drivers designed to dissipate most of this heat using ferrofluid (a cooling liquid) and other techniques. How quickly the temperature of a driver increases depends on the amount of power passing through its voice coil. This means that the safe volume level decrease the longer the speakers will be played at a given level.
During parties and other occasions normally associated with long term loud levels, it is very important that you keep the power levels within the safe area of the de-rating curve. A good indication of a safe long term level is that normal conversation with a person next to you is possible in the same room as the speakers.
Can I play the speakers as loud as the sales person did?
The dealer may have shown the speakers' maximum short term loudness capability for a few minutes. If you have the same equipment as the dealer, you can play the system as loud as you heard it at the dealer's shop; but like the dealer, you must turn the volume down after a few minutes to allow the drivers to cool.
What if my speakers have built-in protection?
Some speakers contain protection devices designed to protect the drivers against overheating. These devices reduce the signal to one or more of the drivers if they detect excessive temperatures, but this may be detrimental to the sound quality.
Won't the protection devices built into my speaker help?
The protection device reduces the likelihood of damage but do not eliminate it. Protection that would eliminate all possibility of driver damage would seriously impair the sound of the speakers. Because no protection devices are perfect, proper use and operation of the system is still very important. You should never assume that the protection device would always protect the speakers.
Is the safe level for the volume control the same for all inputs?
As you use your system, you will notice that some sources are louder than others for a given volume control setting. You also will notice that some records or CD's are recorded at a higher level than others. The volume control cannot be turned up as far on these loud sources or recordings
What if I want to play real loud at a party?
Then you need a pair of party speakers. Just as a dump truck is designed to haul gravel and sports car is designed to handle well around corners, speakers cannot be all things for all occasions. Your speakers are intended to deliver clean, accurate reproduction at normal listening levels. It is not intended for sound reinforcement or long term party levels.
For sound reinforcement or long term party levels you may want to gel a second set of speakers better matched to the high volume requirements. Party' speakers should be a horn loaded or multi-driver design with an efficiency of at least 95db for one watt input and a tone term power handling ability of at least one hundred watts.
Can I use any speakers in a theatre system?
The same precautions that apply to music apply to using the speakers in a theatre system. Stay within the limits of the amplifier and the speakers' power de-rating curve. Don't overdrive the system on spectacular sound effects.
Can I play CD's with test tones on the speakers?
As long as you keep in mind that many test tones are recorded at levels much higher than would ever occur in music. When you play any type of test tone through the speakers, always keep the volume low.
Can I play the system loud enough to listen to it outside the house?
To listen to the speakers while you are outside, the system would have to be very loud and would likely be left that way for a long time. Not being in the room with the system, you would not be able to hear any warning signs of distress. Rather get a pair of speakers that can play music outside when you are there. These are less expensive than you might think and can be positioned in direct sunlight and even rain!
Won't I be able to hear when the system is past its limits?
If the system is distorted you are way past its limit and should immediately reduce the volume level.
How can I tell if a speaker is damaged?
If a speaker has been damaged from overdriving, one or more of the drivers will not be functioning or will be buzzing, There will be no doubt that the speaker is damaged.
Should I be paranoid about damaging my speakers?
Modem hi-fl speakers are not fragile, But by being open about handling limitations that apply to all speakers, we hope to ensure that you will not ever have a problem with your speakers.
What makes one amplifier better than another?
- The better an amplifier's control over a loudspeaker, the more precise the speaker will play the signal, just as it is supposed to be. Therefore, generally speaking, the more power the better.
- The less the distortion an amplifier produces by altering the way the signal was when it entered the amplifier, the better. This distortion can be caused by almost any type of signal processing device such as Bass, Treble, Loudness, "Bass enhancer" and literally almost any switch and unnecessary setting between where the signal enters the amplifier and where it exits the amplifier. The rule is always - the less setting, the better.
- The more dynamic headroom an amplifier has the better. This is because little power is used to create normal levels of playback, but much more is required for an even moderate peaks or climaxes in music. Therefore an amplifier that has high levels of dynamic headroom (short term power) ensures that even when driven to deliver high volume levels, it still has the capacity to deliver clean peaks.
- The better an amplifier's ability of driving difficult loads (low impedances), the better. Usually the bigger and more accurate a speaker is, the more difficult it becomes to drive, due to its impedance dropping very low. The more capable an amplifier is to drive such difficult loads, the better. This ability can often be recognised by checking to see if the amplifier's power rating is stated in a low impedance of 2 ?
What makes one CD / DVD player better than the other?
- The better the transport mechanism (the part spinning the disc and opening/closing) is, the more accurately the digital code gets retrieved and therefore the less the error correction circuits have to work to correct the signal.
- The better the DSP (digital signal processing) circuits, the more accurately the digital signal is transferred and extracted as well as prepared for conversion to analogue. Some players can up-convert the incoming signals and refine inherent flaws in the code to further improve the sound.
- Obviously the better the conversion process from digital (the computer code) to analogue (what us humans hear), the better the quality of the player. Good quality converters make the sound smooth and life-like, whereas cheap converters have a very low resolution with a very harsh sound.
- The better and more stable the power supply of a player, the less chance there are for the player to introduce errors in its operation. If the power is clean, stable and plentiful the player will sound and look drastically better than with an unstable supply full of interference.
History of multi-channel sound (surround sound)
Home theatre, or surround sound (home cinema) as it is also known, has its origin in systems developed for public cinemas, many years ago.
Mono and Dolby Stereo
At first all films were recorded in mono, with one speaker placed directly behind the silver screen. This is actually a very good solution, as everyone in the cinema hears the sound coming from the same speaker(s). As technology improved and music was starting be recorded in stereo (two channels) rather than one (mono), so were soundtracks. The main problem with film sound was that it was really very bad, as the sound was coming off a magnetic tape stuck onto the film reel that deteriorated very fast and left almost nothing butt tape hiss. A company specializing in hiss or noise reduction, Dolby Laboratories was called in to help improve the sound of the film soundtrack by reducing the tape hiss. This became known as Dolby Stereo. The only problem with stereo film sound is the placement of speakers. The speakers were moved from dead centre behind the screen, to left and right on either side of the screen.
From Dolby Stereo to Dolby Surround
Soon it was discovered that sound could be manipulated with basic processors, to extract information form the stereo soundtrack to create a more realistic ambience by playing the extracted information through speakers placed around the listeners. This also had the effect that the room was more evenly filled with sound and the "reverb" or ambient sound was coming from the back and sides of the room just like it did during the recording. As Dolby was already extensively involved with the processing of sound, they further developed this early surround sound and thus it became known as Dolby Surround.
Taking the front speakers from the middle of the screen to a left and right stereo pair created an unfortunate problem. The dialogue that used to be clearly locked with the picture in the middle of the screen had been split in two with bits of dialogue coming from both sides. This proved extremely distracting to the audience, as only the people sitting in the very centre of the cinema could get some form of stereo imaging and have the dialogue in the middle of the picture, where it was supposed to come from. People sitting on either side of the cinema, got most of their sound from either left or right speaker, which was very distracting as the on-screen movement and sound were separated from each other. This led to the development of an additional, centre channel loudspeaker in the middle (as the name suggests) behind the screen to lock the dialogue to the centre of the image on screen.
This was a vast improvement to Dolby Surround and was called Dolby Pro Logic, which is a four-channel system, which consists of Left, Centre, Right and Surround with the centre and surround signals processed out of the left and right stereo signals. As the processing was done with basic decoders, the surround effect was effective, but quite subtle and was limited to four channels. The back two channels were mono (they played the same information) and the centre as well as the back speakers were limited in dynamic range and frequency response.
Digital technology and new surround sound formats.
As time progressed and audio entered the digital era, it quickly became evident that since sound was now being stored and transmitted digitally, sound could now be processed digitally as well, resulting in a huge step forward for surround sound and effects.
The main difference between the previous analogue surround formats and new digital surround formats was the fact that with analogue systems, the maximum number of recordable channels were two. Any desired additional channels of information (centre and surrounds) had to be imbedded within the existing left and right channels and be extracted with a basic decoder.
Digital technology meant more space, more speed and far more flexibility, so the number of audio channels available went up from two to six. Sound could be stored digitally on the film reel or on a linked device. It became possible to record all of the desired channels independently and keep them separate all the way from creation to final replay. The wonderful result of this was the possibility of truly independent channels creating a much more realistic effect and made effects steering infinitely more accurate. Sound was now obtained from 6 (or 5.1) discreet channels namely: Left, Right, Centre, Left Surround, Right Surround and Subwoofer. Because the subwoofer only reproduces a very limited range of sounds and is not full-range, it is referred to as .1-channel. With their vast experience in sound manipulation, the Dolby-company were the first to have an acceptable digital system for delivering this new, discreet, digital surround sound.
This system takes the original number of channels, convert them to digital and compress them into a single stream of digital audio. This signal can then be stored, transmitted etc. At the replay end, the DVD player reads the signal off the DVD, sends it to a receiver (or decoder) that decompresses the digital signal from a single stream, to its original number and then converts it back to analogue sound. The system was aptly called Dolby Digital. The digital era also marked the first time that the consumer could have exactly the same sound as in the cinema because of the storage medium (DVD).
In time, other companies have also come to the fore with new ways of encoding and decoding 5.1 channels of surround sound information for the commercial and domestic market. Probably the best known is a company called Digital Theatre Systems (DTS) with a surround format of similar name.
This format is of much higher resolution than Dolby Digital and suffers from a lot less data compression in the digital domain and is also a lot faster in its data-handling capability. Even though most people who have heard it feel that DTS is far better than Dolby Digital, the Dolby Digital is still better known and more readily available because of its age and cost advantage and also because Dolby Digital is more flexible in transmission and application, it is far more accessible through all kinds of media like satellite broadcast.
Newer and more advanced theatre technologies:
As surround sound became more widespread and well known, the quality and consistency started to vary considerably from one theatre and film to another. When George Lucas, the creator of Star Wars, started making the films, he wanted the film's quality to reflect that of his story and effort that went into producing the film. This meant a new standard in technical filmmaking. He founded Lucasfilm, a separate company that consisted only of skilled professionals, dealing with creating minimum standards a movie theatre, production studio and all equipment had to conform to before they could show his films, to ensure consistently high standards no matter where the film was shown. This was patented as the "bureau of standards" for film-related matters. It is known as Lucasfilm THX. THX literally stand for Tomlinson Hollmann Experiment!
More technological developments
In later years, further advances in digital signal processing have enabled soundtrack producers to add more channels to the standard 5.1 channel mix.
Two formats are now capable of delivering 7 channels discreet (6.1) or 8 channel matrixed (7.1) surround mixes off conventional DVD's. These formats are DTS-es and Dolby Digital EX. DTS-es adds a centre channel at the back to create more realistic surround signal placement and is a 6.1 channel system. The Dolby Digital-EX system adds two extra surround speakers, which results in two back surround speakers and two side surround speakers. These systems are referred to as extended surround systems. This was done to create more realistic fly-over and fly-across effects. Sound can now be sent across, over, through or between only the surrounds! This results in even more spectacular and realistic surround sound, as the more speakers there are, the less stress each speaker is subjected to and the more natural the sound becomes. Unfortunately, this also dramatically increases the cost of producing the soundtrack, so do not expect to find too many of these soundtracks. Luckily, if a customer invested in a 6- or 7.1 surround system, any modern processor will create sound to go to those channels.
The latest addition to surround formats is Dolby Pro Logic II. This new format is a drastic departure from the original Pro Logic, but retains the same genetic roots of Dolby Pro Logic by using non-encoded material (normally stereo) to produce surround sound. This new format is produced digitally and makes use of the complex digital processor, to afford the user a more realistic and natural sounding surround experience from stereo signals. Because of this there is no need for having a specially encoded soundtrack for Pro Logic II and can be obtained from any stereo recording. Most new surround receivers will be able to process this format.
There is also a new version of DTS that works with any stereo signal. This format called DTS neo:6 and is very similar in it's functioning to the way Pro Logic II works. It is said to be DTS's answer to Pro Logic and is included in most surround processors now. Both Pro Logic II and DTS neo:6 operate digitally and deliver staggering levels of realism and precision, despite being converted from stereo recordings. Both formats also offer two versions of their format for optimal use with different programme material. The two versions of neo: 6 and Pro Logic II are music and movie, with independent setups for both. These two different versions optimize the decoding software for the type of programme material used and results in more natural music reproduction and more vivid movie soundtracks.
Both Pro Logic II and neo:6 can also be extended to incorporate the newly added "extended surround" speakers, respectively called Pro Logic IIx and neo:6x, designed to make full use of the complete package of speakers in the system.
Extended Surround 6.1 / 7.1
In later years, further advances in digital signal processing have enabled soundtrack producers to add more channels to the standard 5.1 channel mix.
Two formats are now capable of delivering 7 channels discreet (6.1) or 8 channel matrixed (7.1) surround mixes from conventional DVD’s. These formats are DTS-es and Dolby Digital EX.
DTS-es adds a centre channel at the back to create more realistic centre surround signal placement and is a 6.1 channel system.
The Dolby Digital-EX system adds two extra surround speakers, which results in two back surround speakers and two side surround speakers. These systems are referred to as extended surround systems. This was done to create more realistic fly-over and fly-across effects. Sound can now be sent across, over, through or between only the surround speakers. This results in even more spectacular and realistic surround sound, as the more speakers there are, the less stress each speaker is subjected to and the more natural the sound becomes. Unfortunately, this also dramatically increases the cost of producing the soundtrack, so do not expect to find too many of these soundtracks. Luckily, if a customer invested in 6- or 7.1 surround systems, almost any modern surround sound processor will create sound to go to those channels.
DTS es 6.1
Dolby Digital EX 7.1
Dolby Pro Logic II 5.1
Another later addition to surround formats is Dolby Pro Logic II. This format is a drastic departure from the original Pro Logic, but retains the same genetic roots of Dolby Pro Logic by using stereo material to produce surround sound. This format is produced digitally and makes use of the complex digital processor, to afford the user a more realistic and natural sounding surround experience from stereo signals. Because of this, there is no need for having a specially encoded soundtrack for Pro Logic II and can be obtained from any stereo recording. Most new surround receivers will be able to process this format.
There is also a new version of DTS that works with any stereo signal. This format called DTS neo:6 and is very similar in it’s functioning to the way Pro Logic II works. It is said to be DTS’s answer to Pro Logic and is included in most surround processors. Both Pro Logic II and DTS neo:6 operate digitally and deliver staggering levels of realism and precision, despite being processed from stereo recordings. Both formats also offer different, user selectable, versions of their format for optimal use with different programme material. The three versions of neo: 6 and Pro Logic II are music and movie and game, with independent setups for each. These different versions optimize the decoding software for the type of programme material used and results in more natural music reproduction and more vivid movie soundtracks.
Both Pro Logic II and neo:6 can also be extended to incorporate the newly added “extended surround” speakers, respectively called Pro Logic IIx and neo:6x, designed to make full use of the complete package of speakers in the system.
There have been many attempts to create a higher resolution audio format than what was available on CD. Super Audio CD (SACD) and DVD Audio (DVD-A) were both attempts that failed rather miserably because of there not being enough software (music / movies) available.
With the advent of BluRay disc, a format that holds up to 100Gig of data, it is now possible to include an HD sound option with the HD picture.
Both Dolby and DTS have developed HD (High Definition) sound formats to include onto these discs.
Dolby Digital Plus
Dolby Digital Plus is the next-generation audio format that delivers "better-than-DVD" sound in high-definition packaged media because it requires less compression and provides more channels (up to 7.1 discreet). Dolby Digital Plus also provides new coding efficiencies for future broadcasting and streaming of multichannel audio, which means that it can be broadcast via normal satellite TV like we currently have.
Dolby® TrueHD is Dolby’s latest lossless technology, the ultimate audio experience for high-definition disc-based media. Dolby TrueHD on Blu-ray DiscTM allows viewers to hear exactly what was captured during the recording and mastering process, bringing a palpable and involving audio presence to the home theater experience. This format has a higher resolution than ever before possible on any previous format. For the first time there is real lifelike sound from a consumer format with dynamics (the differences between the loudest and softest pasts of a soundtrack) comparable with what we hear in real life! Together with DTS HD MASTER Audio, this is possibly the best sound quality currently available to the consumer.
HD High Resolution
Designed for projects with disc space constraints, DTS-HD High Resolution Audio delivers a high definition reproduction of the original studio master.
This near perfect reproduction has a constant bit-rate that can range from 2.0 Mbps to 6.0 Mbps. Like DTS- HD Master Audio, DTS-HD High Resolution Audio can provide up to 7.1 discrete channels via HDMI 1.3 or analog connections. The audio resolution can support up to 96 kHz / 24 bit and includes backward compatibility with DTS Digital Surround Core. This is ideal for consumers with legacy equipment. Higher sampling frequencies, greater bit depth and additional channels also contribute to higher-peak bit rates.
HD Master Audio
DTS HD Master Audio provides lossless audio that matches, bit-to-bit, the original studio master soundtrack, and is fully backward compatible with all DTS decoders.
HD MASTER audio is very possibly the best sound quality currently available.
New developments for music and audio:
Following the demise of all older music carriers such as LP, tape and CD and the meteoric rise of music download services, there arose the need to find new ways of achieving fidelity audio at home. The main driving factor is that people, through convenience and availability alike, stopped buying CDs and opted instead for downloading music on their phones and PCs. This gave rise to the development of music servers and similar components that locate one’s music on a central or directly connected storage server and plays it back via the hi-fi system. This has the added benefit of resampling the audio files and making the most of the (often very lacking) mp3 music files.
In addition to playing music from a server and up-sampling the audio quality, many such streaming players have now developed the ability to play audio files of much higher quality than was ever available on CD or DVD. This means that in addition to the convenience of having one’s complete music library available at the touch of a button, a much higher quality music is fast becoming a reality.
It has long been a basic requirement for many people to have music played and distributed throughout their homes, offices or places of entertainment. This was conventionally done by connecting a CD player, radio, satellite decoder or other source of music to an analogue audio distribution system that plays these music sources in the room of your choice. Even though this was a reasonable solution, control and selection was quite limited, mainly by the fact that one has to be at the system to select the desired music, by inserting a CD or choosing a radio channel.
With the advent of digital music streaming services, a new world has opened for distributed audio entertainment. Now control is in your hands in the form of a smartphone or tablet and the user has the ability to browse vast libraries of music and select directly from them to play in the room of their choice.
Online music streaming:
Better still are the plethora of new online music streaming services. These are mostly subscription-based services that charge a nominal monthly fee and offer massive catalogues of music for playback. The main difference in these services to what went before is that they do not save or even download any files to the user. All content (music) is streamed directly from the services directly and all that is required is a stable internet connection. This type of service improves the user experience in a number of ways by offering a much bigger selection of music than most people will ever have as well as the fact that it is instantly available and is totally independent in each room of the home. This also includes a previously stifled format, namely radio. All FM and AM stations now offer their programming over the internet and is included in streaming services for free, which frees up the conventional restrictions placed on a household whereby one radio tuner equalled one station - often resulting in clashes within the family over what to listen to.
All over the world different formats and ways are used to create colour in video pictures. This is known as the colour format. The two most important formats are the North American NTSC and European PAL . In South Africa , we use the European PAL system that is far superior to the older NTSC system.
The way of putting a video (moving image) picture on a screen, comes from the 1920's when the first CRT (cathode ray tube) TV's were invented. Basically, the video image is drawn on the screen as a series of lines from the top to the bottom of the screen. Due to the low bandwidth and resolution available, each image was broken into odd and even lines and the TV would first display the odds then the evens. This is called interlaced scanning and is indicated with an "i" after the number of lines of a video specification. E.g. 480i . The number (480) corresponds to the amount of lines there are in the complete video picture. This line resolution can vary depending on the source used, with a VCR (video machine) being the worst.
In later years, it has become possible to store complete images on DVD and therefore it was not necessary to break the images up into halves. These images were de-interlaced, or differently put, all of the lines of a video picture were drawn in one go from the top to the bottom of the picture. This is called progressive scanning and is denoted by a "p" after the number of lines. E.g. 480p .
The shape of a TV or video picture is referred to as the aspect ratio. The ratio is always given as the width to the height. In all older TV's the shape is almost square. This is known as the 4:3 aspect ratio. The more modern way of displaying a TV signal is in the 16:9 aspect ratio. This is more realistic as the human eye sees wider in it's peripheral vision (like the eye sees, from side to side) than from top to bottom. This is also the way that most films are recorded. People with conventional TV's will see black bars above and below the screen when displaying a 16:9(wide) image on a conventional 4:3(square) screen, whereas a 4:3 image displayed on a wide (16:9) screen will be stretched and people appear fatter.
4:3 on a 16:9 screen 4:3 stretched to fit a 16:9 screen Pan and Scan
CRT or Cathode ray tube, is the conventional "old fashioned" screen type that has been around for eighty years. This is basically a glass tube with a vacuum inside in which a cathode ray (light ray) is scanned (see scanning types above) across the inside of the screen which is coated with phosphor which glows when the beam hits it. This is the oldest, and essentially, an analogue technology. They are restricted in size and resolution, because of the weight and limited brightness with the biggest screens.
These screens have become very common in the last few years due to large screen size and very slim-line design. Plasma screens are an example of a fully digital display system. A plasma display panel (PDP) is essentially a series of gas-filled vacuum pockets between two layers of glass. Each cell is filled with a gas that allows it to glow red, green or blue when excited by an electrical signal or impulse. The three (Red, Green, Blue) cells next to each other, together form one pixel. Each cell is addressed by a central processor that controls the brightness of each cell individually. Because of this, if true black is required, a cell simply is not switched on, and thus deeps blacks can be achieved. Plasma panels can also be very big (as big as 2,6m) and thus it makes them the only flat panel technology for very large scale applications.
LCD technology has been around for quite a long time and have recently become almost commonplace everywhere. Although the display panels resemble that of plasma, the technology is completely different. This is because, LCD uses a backlight panel. This is literally a very large, flat panel of light at the back of the display. In front of the light panel, there are three light filters (Red, Green, Blue) that colour the light as it comes from the back. Because an LCD panel has a backlight, it can be very bright and be used in brightly lit areas, this, unfortunately, also means that achieving true black for very dark scenes is very difficult as the thee filters has to close completely, to eliminate all light from the back, which is almost impossible. The backlight panel also makes it very difficult to make the LCD panels very big and the biggest panels (at 65") are still considerably smaller than the biggest plasmas. LCD can also be used as a projection medium where the backlight is not a panel, but a lamp with lens focusing a beam of light through the filter panel and projecting the image on a screen.
Digital Light Processing is a projection technology where light is beamed from a lamp, through a colour wheel, onto a DMD (digital Micromirror Device) and onto a screen. This, somewhat complex process is the very best way of obtaining a very good quality picture, without pixilation and overly bright colours. This technology can only be used for projection and not for a direct view set like CRT and LCD.
This frequently asked question does not have a blanket and finite answer. The answer simply is: It depends on your requirements and usage. Both LCD and plasma have their advantages and disadvantages. In recent times, many companies have marketed LCD as the latest and greatest technology and Plasma as "old". This is simply not true.
Here are the facts:
- Both LCD and plasma are concurrent technologies.
- Both technologies have specific applications where they excel.
- Developmental work and money is spent on both technologies.
- No end is in sight for any one of the two.
Make your decision based on the following:
- Quick reaction time for fast moving action
- Suitable for very large screen sizes (up to 150Inches!)
- Long lifespan (up to 70000+ hours)
- Very accurate and lifelike colour rendering
- Very good contrast levels (easily 10000:1 and more)
- Generally suffers from screen glare if light shines onto the screen
- Generally consumes more power than LCD
- Heavy screens
- Can be overpowered by strong ambient light levels
- Not available in small sizes - normally only from 37" upwards
- Available in a variety of sizes from tiny to very large
- Generally uses less energy than plasma
- Brighter displays for brightly lit rooms
- Very low glare on screen from light sources opposite the screen
- Generally easy to produce high resolution screens
- Slower reaction times for on screen action, so sport could appear blurred
- Colours easily appears over-saturated
- Over bright screens appear less-lifelike in an attempt to be impressive
- Not available in very large sizes - generally no bigger than 70"
Up to now, TV, video DVD etc. was only available in standard resolution, which is not very good at all. As mentioned before, video resolution is dependent on the colour format and carrier (VHS, DVD, and Broadcast) used and can vary widely. Even the best versions of standard resolution TV are still rather weak and limited in the amount of detail. HDTV or HD gives the user far more detail than before and can therefore display an image with far more detail and clarity than ever before. HDTV is the latest development in TV display technology. It significantly increases the resolution over old, analogue signals and relies on new digital display technologies such as LCD an Plasma to give the user much more detail than ever before on his or her TV.
Below is an example of an image with standard resolution.
Now, observe the image below, with high definition levels of detail.
High Definition generally carries twice the amount of detail that standard resolution images carry. Notice the smoother curves and how more of the actual shape can be shown. This is exactly why HD is so much better than standard resolution.
At first, the most commonly available HD contents will be broadcast (1080i or 720p) and BluRay (1080p), this will change in time to also include HD home videos and internet downloads.
Requirements for HD
1] A 16:9 aspect ratio screen.
HDTV only broadcasts in 16:9 and therefore and conventional 4:3 screen will not be capable to display HDTV in full resolution.
2] A screen that has more than a million pixels.
The two most common HDTV formats are 720p and 1080i. Both numbers refer to the number of horizontal lines in the picture. I and p refer to the scanning type (more on that later). The pixel count for 720p is: 1280 x 720 pixels and for 1080i is: 1920 x 1080 pixels. Although "true" HD is defined as 1920 x 1080, there is also an intermediate format of 1280 x 720, which is also regarded as HD. Some manufacturers also use a panel of 1024 x 768, which even though it is not quite 1080 in horizontal resolution, it can display HD virtually uncompressed and can is regarded as the entry point to HD.
3] An HDTV source.
Most countries have begun experimental broadcasts of HDTV and some like the USA , Europe and Japan have a number of commercially available HD channels. There are currently a number of ways of obtaining a proper HD signal, namely: HD broadcast , HDDVD and Microsoft HD video clip download.
4] An HDTV connection between the screen and the monitor.
All old analogue formats such as composite video, s-video, component video and RGB video, are obsolete with HDTV. The only way of getting a HDTV signal to the screen is via a digital connection such as either DVi or HDMI . No other way will work.
Do I need one?
HDTV's will become a "must have" item in most households soon, offering picture quality many times the resolution to previous analogue TV's. Although broadcasts are still very much at experimental stage, customers will be kicking themselves in a year or two, as broadcasts become more readily available. Also, as technologies become intertwined and all types of systems converge, a TV screen is no longer a stand-alone entity. TV games, computer files, internet downloads, digital sources like still cameras, video cameras, and HD recorders will become part of the entertainment environment and therefore the display system needs to be up to the task of displaying all of the abovementioned sources at the original high resolution.
What is the difference between HDTV and DTV?
DTV is the newer format of digitally transmitting TV signals the world over and receiving them with a set top box via cable or satellite. Although this is far preferable to the old analogue transmissions, it still of standard resolution. HDTV is of much higher resolution and although all HDTV is digital, not all DTV is high definition.
Many suppliers are now exploiting the limited knowledge of the public (and some dealers) and are selling screens as "HDTV compatible". THIS MEANS THAT IT IS NOT A HDTV SCREEN! A digital board inside such a device reduces the resolution in the HD signal and displays it on the standard resolution display panel.
This logo refers to a panel that can display the actual HD resolution of the signal as the panel has a resolution of over a million and is in a 16:9 aspect ratio, but has no HD tuner on board. Such a device relies on the source component to supply the panel with a digital high resolution signal.
As mentioned before, these specifications refer to the amounts of horizontal lines and the letter designation thereafter refer to the way those lines are scanned. Both are within the HD-domain and considered standards for HD signals. So which is better?
Interlaced scanning (i) - 1080i (1920 x 1080) delivers 2 million pixels 30 times per second.
Progressive scanning (p) - 720p (1280 x 720) delivers 1 million pixels 60 times per second.
This leaves us with a 6-of-one and half-dozen-of-the-other scenario. Both systems will coexist as there are pros and cons to both.
This is a resolution which delivers 1080 lines of picture progressively (in other words: simultaneously) on the screen. Effectively this is 2 million pixels, 60 times per second and thus by far the greatest development in commercial picture to date. This format is recognised as "true HD" and is available from BluRay disc and net-based downloads. Nevertheless, this is set to become the standard over the next few years as other, even higher resolution, formats are developed.
One very big advantage to HD screens is the fact that screen size can increase in relatively small rooms. A screen size of between 3-5 times the width of the base of the TV is required for good visual comfort. With standard resolution screens, it was preferable to be slightly further from the screen, or smaller screen size as the ideal, as this lessened the effect of the low resolution and reduced viewer fatigue. Because HD screens have more detail, one can be closer to them, or increase the screen size and have a more cinematic experience in a normal sized room.
An LED-backlit LCD display is a flat panel display which uses LED backlighting instead of the cold cathode fluorescent (CCFL) backlighting used by most other LCDs. LED-backlit LCD TVs use the same TFT LCD (thin film transistor liquid crystal display) technologies as CCFL-backlit LCD TVs. Picture quality is primarily based on TFT LCD technology, independent of backlight type. While not an LED display, a television using this display is called an "LED TV" by some manufacturers and suppliers. Three types of LED are used:
- Edge-lit LEDs This is the most common type in which the LEDs are formed around the rim of the screen, using a special diffusion panel to spread the light evenly behind the screen.
- LED backlighting (Full array)- a multitude of small LEDs are placed behind the screen, whose brightness are not controlled individually.
- Dynamic "local dimming" backlight have the same array of many LEDs, but are controlled individually (or in clusters) to control the level of light/color intensity in a given part of the screen.
Curved screens provide an "immersive" experience, and allowing a wider field of view.
Similar to a movie theater having good and bad seats, there is an optimal position when it comes to watching TV at home. This optimal position is directly along the central axis of the TV with the central point of the screen at eye level. The screen curvature offers a more natural viewing angle and experience due to its lifelike perspective. The easiest way of experiencing the difference a curved screen makes, is by directly comparing the two types of screen side-by-side by starting with the flat-panel (running the same picture) and then switching to the curved panel. The added depth and perspective then becomes instantly apparent and the obvious choice.
Curved screens also allow greater range in satisfactory viewing angles and offer minimal trapezoidal distortion compared to flat-screens. A [16:9] 65" curved screen TV versus a 65" flat television viewed from 4.2 metres from the centre of the TV offers 0.19 degree (~1%) greater viewing angle (based on Samsungs 4200R curved TV). Curved TVs also offer minimised glare from ambient light.
At first Curved screens were seen as gimmicks, but have taken off commercially and had gained acceptance so fast that most manufacturers are now rushing to bring a curved offering to market.
4K resolution, also called 4K2K, refers to a display device or content having horizontal resolution on the order of 4,000 pixels. Several 4K resolutions exist in the fields of digital television and digital cinematography. In the movie projection industry, Digital Cinema Initiatives (DCI) is the dominant 4K standard. 4K offers a drastically improved screen resolution that offer two major advantages:
1) Screen sizes can comfortably and drastically increase to offer true cinematic experience for the viewer and;
2) Definition of images are so fantastically increased that images truly become lifelike to the extent where the viewer no longer notices that they are viewing a digitized version of events, but are more likely to see the images as though viewed through a window. The attached image shows just how enormous the difference is to “old fashioned" TV - or even DVD!
The added advantage of 4K image resolution is that is quickly becoming a standard in commercial theatres to use digital projection as opposed to analogue reels. This means no image degradation over time and (over time) more software available for the home viewer.
4K has become the common name for ultra-high-definition television (UHDTV - or simply UHD), although its resolution is only 3840 x 2160 (at a 16:9, or 1.78:1 aspect ratio), which is lower than the 4K industry standard of 4096 x 2160 (at a 19:10 or 1.9:1 aspect ratio).
The use of width to characterize the overall resolution marks a switch from the previous generation, high definition television, which categorized media according to the vertical dimension instead, such as 720p or 1080p. Under the previous convention, a 4K UHDTV would be equivalent to 2160p.
YouTube and the television industry have adopted Ultra HD as its 4K standard. As of 2014, 4K content from major television networks remains limited.