Audio systems are model classified under three broad categories which are available in the market today: (1) Hi-Fi, (2) Mini and (3) Portable systems. (1) Hi-Fi systems have a PMPO (Peak Music Output Power) ranging between 500 watts and 10000 watts. (2) Mini Systems have components such as CD player/changer, cassette deck and tuner(radio) but in a smaller package as compared to the Hi-Fi systems. Mini Audio Systems range between 150 watts to 500 watts (3) At the lowest end of the audio system market are the Portable audio systems. These can be easily carried / transported as compared to the bulkier Hi-Fi or the Mini systems and are inexpensive. Portables have a maximum power of 150 watts.

PMPO stands for Peak Music Power Output. In India, audio systems are usually rated in terms of the PMPO. Music professionals feel that it is not the PMPO, but the RMS (Root Mean Square), which is the correct and more technical way of measuring music power output. Roughly 8 watts of PMPO power is equal to 1 watt of RMS power. The higher the PMPO (or RMS), the louder you can play your music.

The type of display that comes manufactured with your audio system. The display panel on the audio system displays the status of your audio systems functions, and other such information. All music systems have a Fluorescent Display Panel with varying patterns and graphics preset for the equalizer. Most companies state that their displays are FL (Fluorescent), FTD (Fluorescent Tube Display), LCD (Liquid Crystal Display) DCFD & FLD. But they are all more-or-less the same. It is better to purchase an audio system that has a good, large display which you find easy to read.

The rotary encoder is a knob-like volume control and it usually moves even if the maximum or minimum sound value is reached. This reduces the wear and tear on the volume control. The jog dial is a utility feature found on many Hi-Fi and Mini systems. Apart from volume, it integrates several controls into one easy-to-use & "dial-like" control. The jog dial generally controls the CD tracks, equalizer, radio and amplifier.

Rotary encoders and jog dials can also be used with remote controls which make them more popular today.

For better listening pleasure, audio system manufacturers provide some preset equalizer patterns depending on the various types of music such as jazz, pop, rock, etc. Depending on the sort of music you are listening, you could use these preset modes to get the best out of your music system.

A greater number of preset modes is better as you have a wider variety of preset modes to choose from.

Surround Sound is a feature which makes you feel that you are surrounded by the sound - a sort of a theater -like effect. There are usually four or more speakers, placed in strategic positions in the room. Wires are supplied with the speakers, and if you go in for this feature you will have to make arrangements to position the speakers and conceal the wires. Then there is virtual surround which creates surround effect with even two speakers. When the sound is heard, you will experience a 3-D effect.

Dolby Digital and DTS are digital encoding system for audio signals that can be decoded by a Dolby Digital or DTS decoder of audio system. Dolby Digital and DTS are the most common surround sound format used in DVDs. It uses the compression technology to compress the digital audio soundtrack and gives pleasure of surround sound even with 2 speakers, but one can experience true surround sound with full fledge 5.1 channel speaker configuration.

Audio systems with Dolby Digital and DTS decoders able to produce high quality digital audio signals and giving pleasure of surround sound to listener. These decoders are more common in DVD compatible audio systems.

Dolby Pro Logic II technology processes any high quality stereo (two-channel) movie and music audio into five playback channels of full-bandwidth surround sound. The technology detects the directional cues that occur naturally in stereo content and uses these elements to create a five-channel surround sound playback experience. It is ideally suited for home theater systems, PCs, game consoles, and multi-channel in-car audio systems.

The Pro Logic system is a sound format which uses computer circuitry to route directional information to the appropriate speakers. There are two main speakers (attached to your audio system or kept near it) and two other speakers that are kept in different parts of the room. The sound is played normally through the two main speakers, and the computerized circuitry sends particular sounds through the other three speakers in the room.

For example if you are listening to a war scene, the two speakers in front will play the entire sound as you would normally hear it, and three other speakers placed in different parts of the room will emit different sounds. One surround sound speaker will produce the shooting noises which are high pitched, the other surround speaker will give sounds of bombs which are high bass, low and deep, and the centre speaker (normally on the top of the audio system) plays the human sounds and the hue and cry, thus giving a very rich 3-D surround sound effect.

Dolby Pro Logic gives excellent 3-D effects to the sound.

Graphic equalizer helps you alter the quality of the sound. Rock music sounds best with treble and bass sounds emphasized. Pop music sounds best with emphasized vocals and mid range frequencies. Jazz music sounds best when the low frequency signals are accented. Some systems have options to choose preset equalizer settings, which alter the amount of bass and treble in the music to give a customized sound for a particular type of music.

This feature is a sort of a bass control. Audio systems are sometimes provided with an Extra Bass effect. The feature should be used discretely to boost up the bass so as to make up for bad recordings or make the music sound better.

It gives the user the option to boost the lower bands of frequencies (drums, tablas and other percussion instruments) as desired.

A stereo system that allows you to sing along with the music as though your voice has been recorded with the original soundtrack.

You would have to connect a microphone to your audio system and sing along with the tape or the CD. Normally Hi-Fi systems have the Karaoke feature.

It is best to use a minus-one soundtrack recording when using the karaoke. A minus-one recording is a soundtrack without vocals and is specially made for karaoke.

This indicates the number of sockets available in the system to attach microphones. You can use microphones to record sounds and also for karaoke. Hi-Fi systems normally have one or two microphone inputs, while Mini audio systems and portables may have only one.

The digital echo helps to provide an echo effect to the singing when you are using the karaoke feature.

It thus gives a pleasant touch to the singing and sometimes could be used to make up for not too good singing.

Mic Mix Recording allows you to obtain inexpensive (though, not professional recording quality) vocal recordings at home by mixing your voice on the mike and the soundtrack of the system like it were an original recording.

You could use this feature for small plays, sample recordings or to improve your singing skills.

The sound of the vocals of the singer on the cassette or the CD can be reduced or muffled using this feature. It is normally used on the karaoke mode.

This allows you to sing with your own voice being heard rather than the original singers.

The singer using the karaoke feature and the music from the cassette can be simultaneously recorded on to a blank cassette using this function.

This feature is very similar to the mic mix recording feature where, a multiplex cassette (containing only the music of the song) is played in one jacket and the karaoke mic is connected. In this recording, the multiplex (instrumental) cassette is played through the left channel and the right channel plays the voice that is recorded using the karaoke feature.

It helps in controlling the microphone volume as per your requirement. While using the karaoke feature you can lower or increase the mic volume accordingly with this control.

It is the type of Tuner controls used in the audio system. The tuner can be either Digital, Manual/Dial or Digital Synthesizer. Digital includes preset radio stations that can be accessed easily. You can set the tuner to remember your favourite radio stations and you can recall them easily using the digital feature. A manual tuner necessarily requires you to manually tune (turn the tuner knob / dial) to the wave frequency that you wish to listen to.

Digital tuners are easier to set to an exact frequency.

The tuner function if digital, can be set to remember your favourite radio stations which can be recalled easily. Audio systems could have between 10 to 50 random preset modes.

This helps to save time in selecting commonly used radio stations.

The audio systems with full logic have electronic controls and use superior technology.

As opposed to the older spring-loaded tape controls, full logic (commonly referred to as feather-touch) controls are electronic and do not require you to fully depress a button. Most Hi-fi systems have the full logic feature.

These systems can be fully operated with a remote control. In addition, the tapes themselves endure less wear because the functions (play, fast forward, etc.) are initiated electronically.

Plays both sides of the cassette, one side at a time, without physically having to turn it to change the side.

When set in auto reverse mode and if the entire side has finished playing, (without physically having to be removed and turned) the cassette player automatically begins playing the other side of the same cassette. Some Hi-Fi systems do have an auto reverse mode, however, it may not always be there with the portables and the mini-systems.

This is a convenience feature. If you often listen to both sides of the cassette in one sitting, you would prefer an audio system with this feature.

The cassettes during recording are played and recorded at a higher speed than normal. This facility is provided with the analog cassette players. The cassettes during recording are played and recorded at a higher speed than normal. Do note that by using High Speed recording, the quality of the recording or the recording itself does not get affected. Most Hi-Fi and some Mini systems do have this function.

This feature mainly helps in cassette-to-cassette transfers and helps in reducing the background noise, which could also get recorded during normal speed recording. However, if you wish to record from a CD to a Cassette or a persons voice using a microphone, you will not be able to use this facility.

This is a facility that is offered for recording from a CD to a cassette tape. All systems that have a CD player and also a cassette player have this facility for CD recording.

It is the type of disc changing mechanism that your audio system has.

Disc changers are of two types: Carousel and Magazine and Vertical types. In a Carousel type of CD (Compact Disc) changing mechanism the CDs are placed on a rotary tray (which acts as a platter on which you place the CDs) corresponding to the indicated numbers on the platter. The disc changing technique resembles a carousel. The latest carousel changers allow you to change other CDs while one is still playing. In a Magazine (stack) type disc changer, CDs are placed on racks that are positioned one on top of the other. In a vertical type disc changer, CDs are placed vertically in a tray or are inserted in a slot.

Playing CDs in the rack type of CD Players takes comparatively longer, as the racks need to move, to change from one CD to the other as compared to the carousel type of disc changer which rotates and locates the desired disc in a short time. A carousel however comes with its own set of problems. It may lose its balance because of rough use and that may be a continuous problem in the long run.

A technology that compresses a video file to a fraction of its original size for easy storage and sharing, just as MP3 does for music files. Some DVD players can play DivX files recorded to CDs or DVDs.

The Audio System / DVD Player delivers high quality DivX images. The DVD converted into a DIVX format using a piece of Software that can be burned to a normal CD without any major loss in Picture and Sound Quality.

As like one DVD to DIVX can be burned to a normal CD-R with a Capacity of 700 MB in the same manner 6 DVDs can be converted to DIVX and can be burned to DVD Disc with a Capacity of 7.45 GB with the same amount of clarity and also with a Sound data of 5.1 Channel Surround Sound stored within it. Thus saving Storage Space as well as money for Discs. The customers can easily view all the DivX movies, which they have downloaded from Internet with high quality resolution.

WMA Disc Compatible audio systems combine the CD technology with the WMA (Windows Media Audio) technology. WMA discs capable of holding more audio files than MP3 discs.

Windows Media Audio (WMA) is Windows own file format for compressed audio and is a format similar to MP3 files developed by Microsoft. Files of this type typically have the file .WMA and it is an alternative to the popular MP3 audio format.

This format (which according to independent testing) sounds as good as MP3 audio format and stores audio at half the bit rate (and therefore half the file size).

Composite Output a type of video signal in which the brightness and color portions of the signal are combined. Generally available in VCD Compatible Audio Systems.

Short for Super-Video is a technology for transmitting video signals to the device over a cable.

It transmits the video signals by dividing the video information into two separate signals; one for color and the other for brightness.

When sent from a Audio System / DVD Player, this produces sharper images than composite video, where the video information is transmitted as a single signal over one wire

Component video Output in DVD Players / Audio Systems processes video signal in a way where the chrominance (color) and luminance (brightness) portions of the signal are processed separately. Component video signals provide greater color precision than S-video or composite signals.

Component video signals are superior to S-video because S-video separates the luminance and chrominance portions of the signal, component video splits the chrominance portion into two components which results in improved color accuracy and less color bleeding — are especially noticeable on larger-screen TVs.

Normally, audio is converted to an electric signal and transmitted through an electric wire from the player to the amplifier, etc. Changing this signal to a digital signal and transmitting it through a fiber-optic cable is called optical digital output.

Optical digital audio output is a fiber optic digital audio connection used to connect a digital source component (e.g., DVD player, Audio System, etc.) to a receiver or pre-amplifier. The connector component of the cable uses fibreoptic technology to improve the signal transfer, ensuring there is the minimum distortion between the source and the component or speaker.

Many of the new audio systems models have USB (Universal Serial Bus) Port through which one can connect audio system to compatible devices like MP3 player, Digital Camera or a personal computer. Here audio system is supplied with required connecting cable and compatible software, which needs to be installed on computer to facilitate interaction with music files stored on computer.

This USB network ready audio system enables one to play downloaded music saved on the compatible devices. Thus it allows you to enjoy your favorite music in digital quality coupled with greater control on content.