Altec Lansing ADA 890

Listening Modes - How they sound, 4.1 configuration

4.1 Configuration
Setting the system up with the rear surrounds on their stands, located behind the listening position, creates the 4.1 configuration. This changes the sound field for the following modes-StereoX2, Quad, ProLogic, and Dolby Digital. For the other modes, the sound field is the same, as they only used the front satellite pedestals for playback. This includes Dolby Digital mode when fed any analog feed or digital data lacking AC-3 encoding.

Moving the satellites back adds some cabling, but improves the surround sound in the system immensely. As the rear information is actually reproduced behind the listener, the sonic source is a positive step for directionality. Here's how it breaks down specifically to each mode:

StereoX2 in quad mode improves the response over what was seen in the 2.1 mode. Instead of a wall of sound effect where two drivers stacked on each side shot the same thing, the sound now comes from multiple directions. This makes for a more uniform, but sonically thick, listening environment. Also, the concept of a stereo sweet spot is no longer just between left and right; now, there is a forward position at which there is a balance between front and rear satellites that is desirable. For individual users, this creates a more immersive experience, though some directionality is lost as the sound comes from twice as many sources.

ProLogic mode in 4.1 allows the system to live up to the original design of the decoding format. Specifically, only a limited bandwidth of effects surround sound is sent to the rears. As the driver format is different in the rear (no tweeter for high end reproduction), the rear satellites are well suited to the limited bandwidth reproduction. The rear positioning makes more sense as the surround effects are not washed over by the front channels. Stacking with an offset angle makes for a cleaner setup, but not necessarily better.

Quad mode is again plagued by phase cancellation in the bass unit. Effectively, this renders the mode unusable since there is no bass for gaming, which is usually the true appeal of the quad mode. Also, it prevents any software based decoding of surround sound. Altec is addressing the problem, but until it is solved, this mode is unusable.

Dolby Digital mode is an opportunity for the system to apply its low noise floor and clean digital input to movie quality sound. The performance of the system in this mode is definitely commendable. Though the headroom for a quieter digital signal is somewhat lacking, there is excellent tonal quality at a moderate level. The system has a low noise floor that improves the overall clarity. The bass is less dense than some of the analog modes, but again very clean. This makes for an accurate sound field.