The Multichannel System And Audio Match Up
To use a multichannel system, it has to be properly hooked up to a sound card. You should have no problem with a 5.1 system, which has the standard inputs of three 3.5mm stereo jacks. But if you only have a 5.1 sound card and buy a 6.1 or 7.1 system, you will be offered an upmix to use all the channels with a 5.1 or even 4-channel card. The trouble starts with 6.1 and 7.1 sound cards; some of them, like Terratec, use stereo jack sockets, others, like Creative, use four-pin jack sockets. So getting everything completely plugged in can be difficult - remember that before you buy. We can only regret that the manufacturers have not agreed on a universal standard.
Setting up the satellites is the big problem in multichannel sound. The principle is that surround sound uses three front channels and a variable number of rear channels to restore a sound environment and effects. These should not be directional and you can point them towards a ceiling or wall to diffuse the sound. If you are really serious about it, only trial and error will enable you to optimize your installation so it matches the size and acoustics of your room and suits your taste.
This Dolby file gives you the basic recommended types of surround installation from 5.1 to 7.1.
Of all the problems that are bound to crop up in multichannel installation, especially when used with a PC, getting the front center speaker in the right place is the trickiest. This is the speaker that reproduces film dialogue which, to seem natural, must exactly keep the sound in synch with the movement of actors' lips. In practice, you have the choice of setting the speaker either underneath or on top of the monitor. It is generally easier to it put underneath, but then you need a stand to raise the monitor. Installation above is worth it if, for instance, you mount the three front speakers on the wall behind the monitor; this keeps the desktop clear of both speakers and wires.
Getting the subwoofer in the right position is even harder if you are demanding. The natural place for it is under the desk, but remember the way it reproduces sound can vary a lot with its position. First of all, subwoofers, as far as we know, are designed to work from floor level. Some of them even use the floor as part of their acoustic load and without it they don't work properly. On the floor, it only broadcasts in a half-space, so you gain 3dB.
In any event, you have to realize that the acoustics of a subwoofer depend on its solid angle. However, things are not so straightforward though. In a room where people live, there is a lot of resonance, which varies depending on the position. So you have to find the position that deals best with subwoofer response, resonance in the room and acoustic gain. Of course, this is for perfectionists, but the results can vary quite a lot.
The last point, and the easiest to deal with, is the adjustment of subwoofer levels which vary substantially with the type of sound reproduced. A fairly high level is fine for movies and games, but for music, it should be a lot lower if you want natural balanced sound reproduction. It would be nice to have a film-games/music switch to adapt automatically to these uses but, for the time being, no one has seized the opportunity.
Configuration And Test Conditions
|Processor||Pentium 4 at 2.4 GHz|
|RAM||1 GB DDR|
|Graphic card||NVIDIA GeForce Ti 4200|
|Hard drive||80 GB at 7200 rpm|
|Optical reader||DVD LG16/48X|
|OS||Windows XP Pro + SP1|
|Measurements||DAAS audio analysis system Neutrik 3337 audio analysis system Euraudio Pro 600 sound level meter|
|Sound card||Creative Audigy 2 ZS Platinum Pro (7.1 sound card with Dolby Digital, Dolby Digital EX, DTS, DTS-ES decoders, DVD Audio play), certified THX|
|Listening environment||Room measuring about 12m² and about 36m3|
The response of the speakers was measured by an overall measurement in a typical situation. The results obviously depend on the environment, especially the bottom of the range. For a significant result in the bass range, you have to look at the proximity measurement taken afterwards. Sound levels were measured with our special noise meter used here with the CMSS2 process device on the Creative sound card to broadcast the sound through all the satellites on the system tested.
The technical tests were, of course, combined with subjective ones using a variety of sources and music to evaluate behavior and the quality of sound reproduction. This ranged from situations demanding high sound levels and strong low frequencies (action films, modern music) to ones requiring delicacy and precision (vocals, musical instruments). For this we used DVD Video to view movies and recordings of concerts in Dolby Digital or DTS, DVD Audio in two- and six-channel mode and good old stereo CD Audio in stereo or multichannel mode with the Creative sound card CMSS device. The configuration was optimized for cinema sound using the THX console on the Creative Audigy 2 ZS sound card.