Buying guide – SPEAKERS
Introduction
The heart of any musicsystem or hometheater system or even outdoor rock concerts, speakers are the soul ofaudio-visual entertainment. A speakeris basically an electronic device that converts an electrical signal to soundenergy. These signals are stored in various mediasuch as CDs, tapes, and DVDs. While Alexander Graham Bell could becredited with creating the first loudspeaker in 1876, a number of engineers andscientists after him were responsible for making the version of the loudspeakerwe know today. Loudspeakers are permanent fixtures in many households.
Working of a speaker
In order to understand howspeakers work, we first need to understand how our brains perceive sound. Soundmoves through the air in waves that create changes in the air pressure. Dependingon the frequency and amplitude of these waves, we interpret the sound indifferent ways. The speaker could be considered as functioning in the oppositeway that a microphone works. While a microphone converts sound waves intoelectrical signals, a speaker does just the reverse. Almost all speakers arecomposed of a cone, the broader end of which is covered with a tightly drawn membranecalled the diaphragm. The narrower end of the coil is connected to a voicecoil.
Speakers work on the principleof electromagnetism. This means that when a wire is coiled around a metal barand a current is passed through the coil, a magnetic field is created thatmagnetizes the metal bar. The polarity can be reversed using an alternatingcurrent through the coil. This alternating current causes the coil to moveforward and backward continuously, which in turn ‘vibrates’ the cone. Thiscauses the air in front of the diaphragm to vibrate too, producing sound waves.The frequency and amplitude of these waves depend on the original sound wave. Thesefactors also govern the rate and distance through which the voice coil moves.This determines the frequency and amplitude of the sound waves produced by thediaphragm. Thus, intelligible sound is produced.
Speakers are of three maintypes - tweeters, midrange, and woofers. While tweeters are concerned with high-frequencysounds, the mid-range speakers are concerned with those sound waves in themedian frequencies, and woofers emit the low ‘bass’ frequencies.
What to look for in a speaker
Considering the many brands ofspeakers available in the market as well as the various types of speakers marketedby each brand, it is necessary to get an understanding of your requirementsbefore deciding on which speaker to buy. Below we have listed the main types ofspeakers and speaker sets available so that you can make an informed decision:
- 2.0 Speaker system
The 2.0speaker system includes just 2 speakers, without the inclusion of a bassspeaker. This speaker system is suited for an average music system in yourliving room and occupies less space too.
- 2.1 Speaker system
The 2.1speaker system includes the same two speakers as described in a 2.0 system withthe addition of a bass speaker to emit the low frequency sounds. Music aficionadoswould love this speaker system as it offers ‘bass boom’ without occupying toomuch space.
- 4.1 Speaker system
The 4.1 speaker system includes 4 satellite speakers andone bass speaker or sub woofer. This speaker system offers a better experiencethan a 2.1 speaker system. The 4.1 speaker system is compatible with DolbyProLogic and DirectSound.
- 5.1 Speaker system
The 5.1 speaker system includes six separate speakers beingtargeted by sound signals from six discrete channels – the stereo leftand right front, the stereo left and right surround, the center channel, andthe low frequency channel. This speaker system is compatible with Digital andDolby Digital format. The front speaker is mandatory in the Dolby Digitalformat as all dialogues in any video recording are transmitted through thischannel. The low frequency channel utilizes one tenth of the bandwidth of theother channels because it transmits exactly that proportion of the frequenciesof a full range channel. The remaining 5 channels are full range channels.
- 6.1 Speaker system
The 6.1 speaker system includes 2 right/left channelspeakers, 2 right/left rear channel speakers, 1 center channel speaker, 1 rearcenter channel speaker, and 1 subwoofer. This speaker system is compatible withDolby Surround EX and DTS ES.
- 7.1 Speaker system
The 7.1 speaker system includes 6 satellite speakers, 1center channel speaker, and 1 sub woofer. This speaker system is compatiblewith Dolby Surround EX, DTS ES, and Dolby Pro LogicIIx.
Beforemaking a purchase, analyze the speakers for the following parameters:
- Power
The speaker’s power could be the most important considerationas it is this measurement that determines sound output. Power is measured inwatts. The power should be measured taking the RMS (root mean square) value,rather than the PMPO (Peak Music Power Output). For a normal home system, an RMSvalue of 500 would be sufficient.
- Signal-to-Noise Ratio
Signal-to-Noise Ratio is the ratio of a certain transmittedsignal to the background noise from the transmission medium. Referred to as S/Nor SNR, it is measured in decibels (dB). For a home music system, an S/N ratioof around 80 dB should be enough.
- Controls
Most of the controls for a speaker are usually located onthe front-channel satellite speakers. Apart from the other controls, such as thesubwoofer volume control, surround-channel volume control, left/right balanceand the mute feature, some of the most commonly used controls include the volumeand the bass controls.
- Frequency response
Expressed in hertz (Hz), the frequency response specifiesthe audio range the speaker is capable of. Most speakers have a frequencyresponse of around 20 kHz towards the higher end. The lower end however providesa clearer picture of the speaker’s functionality.
- THX Certification
THX certification would mean that the speaker has passed thequality standards as specified by THX Ltd. Therefore, it makes sense to go infor a speaker system that is THX certified. A THX certified speaker system ensuresthat the sound emitted from the speaker is exactly the same it was when first createdand mixed. Since THX Ltd. is a respected body in the audio technology arena, aspeaker system with THX certification is seen as setting the standard for highquality sound.
- Headphone Jack
A headphone jack is a handy option incorporated into yourspeaker system. This jack comes in use when you wish to listen to music at highvolume without disturbing anyone else. As soon as the headphones are insertedinto the headphone jack, the speaker outputs usually become mute. The headphonejack is usually close to the volume controls of the speakers.
Making a decision
View different speakers displayed onwww.etronics.com. Of course, if you require a speaker set for use at home,you would not be going in for powerful speakers that are usually used in theoutdoors. Depending on your usage as well as budget, you could view the price-wisedistribution of the speakers by clicking on the following links: Under$50, $50- $100, $100- $200. Check speakers from reputedmanufacturers such as Pyle.
If you wish to have a truly cinematic experience at home,you could go in for a home theater speaker system that is composed of a minimum5.1 speaker set. For a casual ‘weekend’ music listener, a 2.1 speaker systemwould be just about sufficient. Make the right choice and get set for years ofentertainment with your speaker system.
