Audio Systems Product Guide

An audio system is a sound system that lets you play records or discs and lets you listen to it through speakers.

Listening to sound in the 21st century is redefined. Not only do we listen to music and songs from records and CDs but we can also use audio systems to hear sound with video. You can connect your television to stereos and DVD players to multichannel sound systems. Some sound systems even come with DVD or Blu-Ray players and are called Home Theater in a Box (HTiB).

Most HDTV, while it can still be used with stereo, adds the capability of using 5.1 channels to deliver sound. This means that, with HDTV broadcasts, there are tracks of audio to drive 5 speakers and a subwoofer for sound that rivals that of a movie theater. This concept drives the enthusiasm of home theater. Not only do you have a widescreen, high-definition TV, you also have encompassing sound all around you.

5.1 Channels mean you are using 5 speakers to deliver sound. They consist of front left and right speakers (similar to stereo) but add one center channel speaker (generally placed on or near your TV screen) and two rear speakers (left and right). The ".1" is a subwoofer which may be fed by all audio channels together. The role of the subwoofer is to seliver really low, deep frequencies that ordinary speakers barely get close to. This helps you hear the rich sounds of a cavernous theater within the dimensions of your living room. The subwoofer also allows the 5 surround speakers to be really small. Most can hang on walls. This helps them occupy less space, keeping room décor in balance.

An audio system developed for use with a TV is generally 5.1 channels and comes with 6 speakers - 5 surrounds and 1 subwoofer. These audio systems, called Home Theater Sound or Surround Sound Systems, have a central amplifier that processes the sounds from items connected to the system (i.e. Television) and delivers them out to the speakers. The amplifier power is divided to the 5 surrounds. Additional power, often more than to surround channels, is delivered directly to the subwoofer because driving bass frequencies clearly requires more power.

In addition, some Home Theater Sound Systems may also include a built-in DVD player. DVD discs also deliver 5.1 channels + video out to your connected TV. A DVD player can also play audio CDs so it can double as a CD player as well. There may also be a connector or dock for adding your iPod, MP3 player, or Mobile Phone for play through your sound system.

Some systems may also include a Blu-Ray disc player. Blu-Ray discs resemble DVDs but use a different system that allows them to hold more audio and video information. So if you have a widescreen TV that can display the highest 1080p HDTV mode, only Blu-Ray can deliver that performance. Blu-Ray offers higher definition (higher resolution) than all current standards of HDTV. Blu-Ray players are also backward compatible for play of DVD and CD at their native standards.

Stereo

Most remember stereo. Stereo meant two channels of sound using two speakers. It added a new sense of space and realism when listening to music. Before the development of stereo, all audio systems used one channel to one speaker.

The technology was developed through Bell Labs, in the 1930's, making stereo recordings of Leopold Stokowski and the Philadelphia Orchestra. A few years later, Walt Disney released “Fantasia”, an animated film using classical music to accompany the visual. Unfortunately, appreciation of this film didn't happen for several years since most theaters were unable to deliver 2-channel stereo.

Stereo recordings began to emerge in the 1950's. Prior to that, most records sold were played at 78 RPM (revolutions per minute) on discs that were either 10 or 12 inches in diameter. Each disc side held no more than 6 minutes of recording. As stereo used two tracks instead of one, the capacity of a 78rpm side would be about 3 minutes. That was deemed impractical. The development of the commercial long-playing record, at 33rpm, occurred in the late 1940's. Because the Long-Play record had a 20 to 30 minute per side capacity, adding a stereo groove was finally practical for consumers.

By the 1950's, stereo sound emerged within the middle-class and rich. Everyone wanted stereo record players. For the next 15 years or so, people were able to buy a mono (one channel) or stereo version of a record.

The sound technology was briefly overshadowed by Television - which merged audio and video. TV was still mono and early programming was, essentially, an extension of the radio. Most shows were recorded in both TV and radio versions.

Stereo penetrated the general public by the 1960's. Early TV models with two speakers were really binaural. The same sound would be delivered to both left and right speakers. It was quasi-stereo. FM radio turned stereo in the early 1960's, originally called “Multiplex”. Rarely, the sound portions of TV specials were simulcast over FM stereo for 2-channel sound.

Even though cassettes and CDs replaced records, 2-channel stereo was the sovereign sound system until the 1990's.

The Video Cassette Recorder emerged in the 1980's and now the availability of stereo sound occurred by connecting your TV and VCR to your home audio system. Simultaneously, Dolby Laboratories, a group of sound engineers aimed primarily at movie theaters, began designing surround sound features for stereo receivers. Early versions were relatively unpopular until Dolby released ProLogic, which added a center channel to a quasi-surround effect.

Dolby Digital Surround

Among surround sound engineering for the home, Dolby emerged as a leader.

Most 5.1 Channel Audio Systems feature Dolby Digital surround decoding. This means it can interpret DVD discs encoded with 5.1-channel sound.

Dolby Digital is a powerful audio format that provides up to 5.1 separate channels of crystal-clear digital surround sound, bringing entertainment to life. A worldwide standard in film, broadcast, and DVDs, Dolby Digital delivers unrivaled audio in home theater systems for an exciting, enveloping surround sound experience. This is the most common surround audio system and was initially adopted for use with HDTV broadcasts. You may still find this in the credits of new movies and television shows.

Dolby Digital EX and Dolby Digital-Plus are worth a mention. These systems were developed to expand the surround effect further to 6.1 and 7.1 channels. Less frequently found in audio systems than components, surround is enhanced further by adding more speakers. The drawback is that fewer recordings and virtually no broadcast TV is available for decoding by these surround formats. Dolby Digital-Plus, at least, by virtue of being 7.1 channels, can faithfully decode Blu-Ray HD discs that offer the potential of 7.1 channel surround.

Dolby TrueHD

Dolby TrueHD is Dolby's latest lossless technology, the ultimate audio experience for high-definition disc-based media. Dolby TrueHD on Blu-ray Disc allows viewers to hear exactly what was captured during the recording and mastering process, bringing superior audio presence to the home theater experience. Its intent is to provide the same mix as the producer hears for any channel configuration from 2 channels to 7.1 channels. That means you'll get superior sound from CD to DVD to BluRay. It'll even work with your old VCR, if hooked up to your sound system.

According to Dolby Labs, the sound is bit-for-bit identical to the studio master, so listening at home is like being in the studio while the movie or video is being mixed, or at the sound board at a live concert. With Dolby TrueHD, the listener hears exactly what was captured during the recording and mastering process. Coupled with the high-definition video of Blu-ray Disc, Dolby TrueHD unlocks an unprecedented home theater experience with sound as stunning as the spectacular picture. Dolby TrueHD can support more than eight audio channels. Blu-ray Disc standards currently limit its maximum number of audio channels to eight.

Dolby Virtual or Dolby Virtual Speaker

This is a really cool system for many of us who want to experience surround sound without getting 5 or 6 speakers. There are home-theater systems that come with up to 3 speakers. The third speaker is usually a subwoofer. Dolby Virtual Speaker technology simulates a highly realistic 5.1-speaker surround sound listening environment from as few as two speakers, making it an ideal technology for digital TVs, stereo mini-systems, PCs, and a variety of consumer audio/visual products. Dolby Virtual Speaker technology also creates a wider two-channel environment during playback of stereo CDs and MP3s, and when combined with Dolby Pro Logic II processing, (for example, in an audio/video receiver or PC), delivers a virtual surround listening experience from any high-quality stereo source. More than a simple "expanded stereo" performance, Dolby Virtual Speaker incorporates highly advanced algorithms and extensive room-modeling technologies to reproduce the sonic spectrum and dynamics of a properly placed 5.1-speaker system in a room environment.

In certain recordings it really sounds as if the noise is coming from here or from there.

Though you may hear about, or your system also has sound enhancers by DTS or TruSurround, Dolby is pretty much the standard with which audio media producers often comply.

While speakers come with your audio system, proper placement helps assure best performance.

Front speakers (left, right, center) should be positioned at ear level (when you're seated). Suggested height for the rear surrounds is above ear level, as soundtracks are likely to be optimized for that location.

Beyond keeping it on the floor, there's no specific rule for placing the subwoofer, as bass sound is nondirectional. However, the amount of bass may vary depending on room location. You might want to try a few different places to determine what's best for you (sometimes moving the speaker even a few inches can change the sound).

5.1 Setup

This system has six channels: five full-range channels, and a low-frequency effects channel (the .1 of 5.1) usually expressed through a subwoofer. Many DVDs and digital broadcasts feature a Dolby Digital (5.1) soundtrack, so this will give you optimum sound for most programming. It also most closely approximates the sound in most cinemas.

6.1 or 7.1 Setup

The most advanced home theater systems feature six (with Center Back) or seven (with Left Back and Right Back) full-range channels that allow viewers to take advantage of Dolby Digital EX soundtracks and Dolby Pro Logic IIx matrix-surround decoding technology. Both of these processes add surround information for greater realism and more dramatic effects.

Correct home theater speaker placement is the key to a seamless, immersive, surround sound that is very important in a home theater experience.

Placement for the center channel requires the speaker to be placed either centered on top of your TV or just below. This speaker presents the sound you hear from behind a screen at the theater.

The main front left and front right speakers should be placed equally distant on either side of your TV; for best performance, these speakers should be at least 6 feet apart. These carry the bulk of the soundtrack, including music and primary effects.

The two rear surround speakers are best placed alongside and slightly to the rear of your main seating position. This will help mimic the sound field as originally recorded in dubbing theaters when mixing movie soundtracks.

In some cases, usually on higher priced systems, a microphone is included to help calibrate sound output to your room's particular acoustics.

The key thing to Home Theater in a Box is that you get a full home-theater sound system, sometimes with DVD or Blu-Ray player built-in, to easily connect and sync with your widescreen HDTV. It's designed to be simple and easy. All speakers include speaker-connecting wire and the connections are designed so that no tools are necessary.

Where some may feel challenged about wiring the rear speakers in a room, some systems include wireless rear speakers or offer them as options. Clearly, when wireless speakers are offered, be certain that they are designed to perform with the system you're buying.

Because all the parts of the HTiB are perfectly matched, power per channel is less critical since this was designed to perform as a system. Most systems from Sony, Panasonic, Samsung, Bose, Onkyo, and Denon have ample power to deliver outstanding sound.

Many systems are iPod friendly. This means that an iPod dock is included or available as an option. Take your iPod, dock it, and play it through the system.

There may be an input port available for connecting digital media players from other brands.

Because of the wider scope of video entertainment, home theater audio systems outsell stereo systems by a wide margin. Stereo systems still have a place in an office or den because of their small size. In a few cases, stereo systems do have auxiliary input jacks just in case you do want to attach your TV to it. It will likely sound better than the speakers built-in to your TV.

If you want to experience full television and video surround sound effects, you must opt for home theater. Most home theater systems are also backward compatible to play stereo. So a home theater sound system or HTiB is, overall, the better buy.

Stereo sound systems generally sell in a range from $50 up to around $1,000. Most systems above $250 offer excellent sound. Home Theater sound systems are generally priced in a range of $200 to about $3,000. You can get excellent sound from most systems over $500.

How do you decide on the best home theater system for you? In the $500 (and up) range, amplifier watts per channel is less critical since all speakers and components are matched. Many include a radio tuner. Several include a DVD player while some may also offer a Blu-Ray disc player.

You should consider what features are necessary for you, and which ones can be waived. There is no point in paying for a function or capability that you may never need or use. Some packaged home theater systems feature a disc changer that holds three discs or more, while the smaller systems use single-disc players in an effort to save space. Consider how important the convenience of a changer is to you. A Blu-Ray player integrated into a system can add a premium to the overall system cost. So can wireless speakers, if included.

There is a little trick you should be wary of. How power per channel (watts) are determined. Lower priced units may appear like this:

• Surround: 100 watts x 5 (8 ohms, 1 kHz. 1% THD)
• Stereo: 100 watts x 2 (8 ohms, from 20Hz to 20kHz, 0.7% THD)

Note that Surround power parameters are less critical in the home-theater mode than stereo. This means there is less power and clarity when the amp is switched from stereo to home theater. What you really want to see is:

• Surround: 100 watts x 5 (8 ohms, from 20Hz to 20kHz, 0.7% THD)
• Stereo: 100 watts x 2 (8 ohms, from 20Hz to 20kHz, 0.7% THD)

This specification generally emerges in home theater sound systems priced at $500 or above. It helps deliver an edge in overall sound performance and that's what all this is about.

A key to seamless surround sound is proper speaker placement. A guide usually comes inside the home theater sound system package.

Consider how often you plan on using the sound system. If you plan on enjoying videos and TV several hours each day, or listen to music as well, it's advisable to spend a little more on a home-theater audio system. You may find it to be a worthwhile investment. This is an essential accessory for any HDTV.