Home Movie Theater Technical Terms:
 
AV：
 It means Audio and Video system which we usually call Home Moive Theater.

Dual Decipher:

 It means the decoding on Dolby Digital and DTS which are the digital encoding audio frequency that is widely used currently.
5.1 Channel
 It means there are six different sound signals of AV system, including left main sound channel, middle-allocated sound channel, right main sound channel, rear-left surround, rear-right surround, and superheavy bass, so as to create a real onsite feeling. Among them, because the superheavy bass is not a full channel, it is called 0.1 channel.
Separate Magnify:
 It means the magnifying power circuits of the intellective AV center can separately magnify signals from different sound channels.
Equal Power:
 It means the power rates of five separate magnify sound channels on the intellective AV center are exactly the same, which is the standard of AC-3 and DTS surround sound technology.
Full Frequency Band:
 Complete and entire magnifying of sound source without any distortion and losing any details.

Home Moive Theater Surround Technical Terms:
 
Dolby Pro Logic：
 Analog signal which recoveres from two sound channels to four sound channels after processing, the exact analog stereo positioning including L, R, C and S sound channels. The surround sound is monophonic. The disc sources are VCD, DVD, and LD. It is the surround technology of early period.
Dolby Digital：
 Digital signal and 5.1 channel source. After processing 5.1 channel is recovered which includes L, R, C, SL, SR, and SW. The six sound channels are completely independent with real effect and clear details. The disc sources are VCD, DVD, and LD. It is currently the most popular surround sound technology. The THX processor has been added based on the Dolby Pro Logic or Dolby Digital technology so that there is more extension sound field. The disk sources are VCD, DVD, and LD. It is mostly used in professional movie theater.
DTS：
 Digital signal and 5.1 channel source. After processing 5.1 channel is recovered which includes L, R, C, SL, SR, and SW. Compared to Dolby Digital, DTS has more details of sound and better tonality. Transient state response is faster. The disk sources are DVD, LD, and CD. It is more advanced sophisticated technology.
THX Surround EX：
 Digital signal and 5.1 channel source. After processing 6.1 channel is recovered which includes L, R, C, SL, SR, and SW. Compared to Dolby Digital, there is one more middle-allocated surround sound channel which provides more extension sound field. There is better sound link-up. The disk sources are DVD and LD. It is the most advanced surround sound technology.
DTS ES：
 It is similiar to THX Surround EX. The 6.1 sound channel surround technology is developed under the technology of DTS. Compared to DTS, there is one more middle-rear allocated sound channel which has made the echo effect more perfectly.

Speakers's Layout of Home Movie Theater:
 
Main Speakers:
 The height of radiate sound center of left and right main speakers should be almost the same or slightly lower than the screen center. The back and rear position should be on the same horizontal line as the screen center. The layout of the speakers should be based on the policies of better stereo sound and not keeping sound and images out of the screen. Usually it is perfect to have a 30 degrees angle between the left, right speakers and the audio-visual point. In order to avoid over reflection, the main speakers should not be too close to walls (except for the speakers which have front ventage holes.) The heavy bass sound of the main speaker should be facing outside, but keep at least 20cm's distance away from walls.
Middle-allocated Speaker:
 It can be on the same horizontal line as the main speakers, or a little bit rear, but not front. Meanwhile, it has to be on the same vertical line as TV, usually on top or bottom.
Surround Speakers:
 There is not very strict requirement for surround speakers except for not being too close to listeners. Two speakers could be separately on the two sides of the back of the listener, both speakers facing the listener and facing to each other. The tone axis could be about 1 meter's height above the listener.
Super Heavy Bass Speaker:

Usually it can be located on the left or right side of the TV. If there is not appropriate position, it can be on any other places, because the sense of direction for super heavy bass speaker is not very clear.


Requirements for outstanding performance of home movie theater:
  If you want to have an outstanding performance of home movie theater system, you have to consider about the proper fitting of AV intellective central machine and the speakers' system. The factors for proper fitting are very complicated. Genearly speaking, it's better to choose some famous brand of home movie theater system, because these systemes are designed for conformable proper fitting of vaious factores.

Impedance:

 The pre-set impedance of speaker system (usually 4-8 Ampere) should be inside the pre-set output impedance scope of AV intellective central machine (usually 4-16 Ampere). If the impedances are not fitted, the low frequency volume will be weakened, the sound will be dry, richless with distortion.
Power Rate:
 The output power of AV central machine should be accommodated with the pre-set input power of speaker. The former one should be one quarter larger the latter, because all actual speakers have a certain amount of overload capacity, which allowance volume is 1.5 times of the pre-set power.
Sensitivity:
 The output power of AV intellective central machine is large, but it doen't mean that the speaker motivation is strong. Instead, the speaker sensitivity is the essential factor. AV intellective central machine should be accommodated to the speakers with higher sensitivity, but when the sensitivity is too high, the sound timbre will be too thin, too bright, can not represent music details without enough charming.
Sound Timbre:
 Sound timbre is subjective. Different audioes have different timbre characteristic. Some are warm, some are cold, some are soft or hard. By properly arranging the equipments, emphasizing on advantages and avoiding disadvantages, cold and warm complementing to each other, matching soft with cold, so as to achieve perfect sound timbre. The matching of sound timbre can also be attained by using professional audio wires in order to reach an ideal status.

Three Solutions for Home Movie Theater:
  There are three solutions of digital decoding system (Dolby Digital or DTS) for home movie theater.
Economical Type:

Internal digital decoding chip DVD + 5.1 sound channel AV intellective central machine.

DVD with internal Dolby Digital or DTS decoding chip can separately transfer the decoded multiple sound signals by a group of simulated audio frequency lines to an AV intellective central machine with 5.1 channel independent enlarged circuit for enlarging. This solution is very economic and easy to realize, because presently most DVDs produced by domestic manufacturers have internal Dolby Digital decoding chip. But it is not ideal from the way of sound effect.
High Class Type:

Digital signal output DVD + AV intellective central machine with internal digital decoding chip.

After reading by DVD, the digital signals are transferred by optic fibers or coaxial lines to the AV intellective central machine, and decoded by the internal digital decoding chip of AV machine. Then the decoded signals will directly reach the independent enlargement circuit for enlarging. This solution cost a bit more, but you can obtain better sound effect. Besides, the AV machine with DTS and Dolby Digital contains higher technology.

Professional Type:

Digital signal output DVD + Digital decoder + Multiple channels AV amplifier.

By connected an intellective decoder between DVD and AV amplifier, the digital signals can be transferred by optic fibres or coaxial lines to the amplifier, which will again transfer the decoded sound signals to the AV amplifier for enlarging by a group of simulated AF lines. This solution is expensive, but you can reach a Hi-Fi effect of home movie theater. It is suitable for audio fans who require highest tonality. Some audio fans even use serveral double-sound-channel machines for separate amplifying.


Application of DSP effect of home movie theater
 

DSP（Digital Sound Processing）is a digital sound field processing technology developed by Japan Yamaha company, which is used for simulating various onsite sound effects when repeating different programming sources.

Except for listening to music or watching the movie that is not encoded digitally, you can get an ideal onsite effect by using DSP analog function when watching TV programs every day. Nowadays all TVs are two channels stereo which is dull and tasteless. Specially when watching sports games ore live singing performances, you can never find the overwhelmingly onsite feeling. At this time, you can transfer TV sound to the AV intellective central machine with DSP function, choose relative DSP function mode according to different programs, then you can simulate onsite effect to make you as excited as when you are on the real sites.

What you need to pay attention is, that some domestic manufacturers just make some simple fine-tuning to the sound assignment and frequency scope, when designing the sound processing circuits of the machine, and mark the symbol of "DSP". Acttually, there is no Yamaha DSP chip in the machine, the real Yamaha DSP chip only has eight typical analog sound field effect.