Front Channel Loudspeakers
Front channel imaging is also extremely important in producing accurate sound. For films, the sound has to match the picture perfectly. Conventional two-channel speaker designs are constructed to present a good solid image over a 45 to 60 degree angle. If you spread the speakers too far apart, you get a hole in the center image. Place them too close together, and the sound stage collapses into a fuzzy mono sound. In a multi-channel sound system, sound images are formed between Left and Center and Right and Center Speakers. This means that speakers must be precise enough in their imaging characteristics to create a sound stage over half the separation distance normally expected for a two-channel system.
Home THX LCR front channel speakers improve dialogue intelligibility and imaging in two ways. First, they provide wide horizontal dispersion. This allows for people sitting off-axis to hear full and flat frequency response. The second technique is to control the speakers' vertical dispersion. Acousticians have found that the ceiling and floor reflections deteriorate a speaker's ability to image. In addition, the coloration from these vertical reflections cloud intelligibility.
Surround Channel Loudspeakers
The purpose of a surround channel is to surround you with sound. The problem is that this is tough to do with just two speakers. Decorrelation takes care of Left/Right spaciousness, but what about wrap around envelopment? If a director chooses to place you in a wind storm, conventional speakers leave you with the impression that you're hearing the windstorm through two open windows.
The Home THX Diffuse Surround Speaker is designed to provide a "movie without walls" experience. It does this by painting the walls and the ceiling with sound. It sends very little sound towards the listener. The sound reflecting off the room’s walls and ceiling provides an enveloping soundfield, immersing the listener in the movie experience.
The total energy radiated by a speaker in all directions is called its "Power Response". The Home THX Diffuse Surround Speaker is required to have a flat power response. This means that the total energy radiated by the speaker (in front, above, below, behind, and to the sides) must together average a flat frequency response. With the total speaker energy being flat, a listener anywhere within the surround speaker's null area will hear flat frequency response.
Subwoofer Loudspeakers
The final requirement for accurate multi-channel sound reproduction is accurate deep bass response. All THX subwoofers are designed to precisely match LCR speakers through the Electronic Crossover in a Home THX Controller or Receiver. THX Subwoofers must have an accurate in-room response down to 20 Hz. Approved systems must be able to play 105 dB sound pressure level or louder without distortion. THX subwoofers come in a variety of configurations and can be use singly or in multiples to match the requirements of even the largest listening room.
form http://www.thx.com/mod/techlib/speakers.html
LFE: 低频信号 可通过增加重低音解决,标准上文Subwoofer Loudspeakers 讲的很清楚.
