Altec Lansing ADA 890

Listening Modes - How they sound, 2.1 configuration

2.1 configuration
The ADA890 system has a number of sound configurations that are selectable at the right front satellite pedestal. The mode button cycles through the various modes in the following order: Stereo, StereoX2, ProLogic, Quad, and Dolby Digital. Depending on the input configuration, some options are not available or operate slightly differently than the description; these differences are described with the relevant connection configurations in the setup section.

For those users choosing to set up the system with the rear satellites stacked on top of the fronts, the system falls into a 2.1 configuration. However, the "rear" satellites are still independent, and angled away from the user to simulate a surround field. This system works pretty well.

In stereo mode, the main front satellites operate along with the subwoofer to reinforce the bass of the system. This mode works for both the digital input as well as the analog input; in each case it uses the front stereo information provided. The coverage is comparable to a near field stereo setup; there is good separation at the listening position between channels. For stereo music playback, it is the most straightforward option.

The analog input, when routed to stereo input, has a warm tone that has strong fill through the midrange section. The analog input also carries a denser bass response that will provide more thump and power. The highs, provided from a separate driver in the front satellites, are well balanced with the rest of the frequency spectrum. The bass response to the bass adjustment is strong; it is responsive to adjustments both in the highs and lows.

The digital input provides a somewhat cleaner sound, with different emphasis in the spectrum. The bass is clean and defined, though has less strength in the digital mode than in analog mode. The highs carry more presence in proportion to the bass as a result, moving the sound more out front. Dialing the highs back a bit, and the bass up provides a mellow sound that fits the input well.

StereoX2 moves the front input information to both the front and rear satellites. As the rear satellites do not have the independent tweeter, this changes the sound characteristics somewhat. The lower highs take control of the sound, with less bass presence to keep up. This is especially the case in the 2.1 mode setup as the sonic source for mids essentially doubles, plus the rear satellites are trying to handle frequencies that would be better suited by a tweeter.

The sonic effect is a thicker sound, with less separation between channels. The mids and highs are more emphasized, and less responsive to the tone controls. The coverage of the system is larger due to the angling of the rear satellites, so the soundfield is larger. In the analog mode, the added midrange takes what was previously warmth in the sound and overemphasizes it. Switching to digital mode, the added midrange fills in some of the accuracy to make the sound smoother. In both input modes, the bass needs to be dialed up some.

ProLogic mode is the next option. This selection processes the input to send certain parts of the sound stream to the rear satellites and other parts to the center channel, were it present. In this case, it serves to add the midrange frequencies to the rear sats to create a more immersive soundfield. The limited frequency range helps limit the wall of sound effect seen in the StereoX2 mode, as the rear sats aren't handling high frequencies their drivers aren't designed for.

ProLogic mode is only offered for the analog input section, and will be silent in digital only mode. The combination of analog mode and ProLogic makes for an enhanced listening mode for stereo audio. It isn't the pure stereo mix, but it is an enjoyable listening environment. It's also useful for getting surround sound out of now Dolby Digital encoded sources.

Dolby Digital mode serves a couple of roles, depending on which input is routed to it. With the analog input, it acts just like Stereo mode. It performs this same function if the digital input is not encoded with AC-3 data. Remember that the rear satellites are inactive in this mode if the input is not encoded with surround data. When AC-3 data is present, the mix is decoded and reproduced through the appropriate drivers. As there is no center speaker in the system, the center channel is downmixed to the front main speakers. In the 2.1 mode, the surround speakers shoot off to the side. For a single listener, this can somewhat approximate a surround field, though is less effective than running the system in 4.1 mode.

Quad mode is available when four channels of analog information are connected. In digital input mode, the system will only operate in normal stereo mode. In analog quad mode, it reproduces the front two channels to the front surrounds, and the rear channels to the rear satellites, as would follow naturally.

Unfortunately, there is a technical problem with quad mode. According to Altec, the system originally was designed as an OEM solution to accompany a Dell computer. The original configuration included a four channel sound card in which the rear channels were wired out of phase with the front channels. To correct for this in the original system, Altec wired the rear input out of phase with the front channels. This same architecture is included in the current system.

However, most current four channel sound cards are wired in phase. This causes phase cancellation in quad mode, especially in the subwoofer. The low frequencies from both the front and rear are routed to the sub for reproduction. They are 180 degrees out of phase, and cancel each other out completely, resulting in little to know bass in many situations. The result is unacceptable sound when in quad mode.