Yamaha DSP-A2070 AV amplifier

A veritable tour de force of digital signal processing, Yamaha's new top integrated amplifier, the DSP-A2070, shows what can be done when a company takes a good hard look at the connection, switching, and signal-processing demands of an elaborate home theater setup. The A2070 has, for example, connections and switching for eleven inputs: phono, CD, tuner, laserdisc, two audio recorders, satellite decoder, and three (!) VCR's, plus a rear-panel auxiliary audio/video input duplicated on the front panel.

Some rare or unique features useful in home theater systems are included. For example, along with the test signal required for Dolby Pro Logic channel balancing, there are provisions for using the signal to set the levels for the additional speakers that can be used in some of the amplifier's other modes. Furthermore-and this can be extremely valuable-there are several subwoofer-balance test tones to help you set a system's subwoofer level properly. An input-trim control enables you to match the levels of all the inputs to that of the CD input. Finally, there's a five-band graphic equalizer-adjusted by means of the amplifier's front-panel control buttons and display-for the center channel.

For those not satisfied with the output power provided by the DSP-A2070, which should be sufficient for all but the largest listening rooms or truly lease-breaking levels, every possible speaker output signal is also provided at line level for feeding external power amplifiers. That includes the two main channels, the two surround channels, the two "front-effect" channels, the Dolby Pro Logic center channel (yes, the A2070 contains seven power amplifiers), and the three subwoofer outputs (one mono and a left/right stereo pair), which are filtered to remove frequencies above 200 Hz. A switchable Bass Extension circuit provides a slight boost centered at 75 Hz and a relatively steep rolloff below that frequency, which may help extend the bass response of some small main-channel speakers.

All back-panel line-level audio connections are via phono jacks, unfortunately in a vertical array. Composite-video inputs and outputs are also phono jacks, but every video connection, even the auxiliary one on the front panel, also has a corresponding S-video connector. Speaker outputs are multiway connectors that accept stripped wires or banana plugs most easily. There are three AC convenience outlets, two of them switched.

Pride of place among all the DSP-A2070's features must go to its digital signal processing (DSP) facilities, which Yamaha says are significantly more powerful than those of its highly regarded DSP-A1000 amplifier. They add, through extra speakers placed around the room, artificial "reflections" derived from the original signals. When placed and timed properly, such reflections can go quite far in acoustically mimicking a real performing space, transforming the sound of a home listening room into something else altogether.

When fully configured, the DSP system provided with the A2070 requires seven speakers (plus one or two optional externally amplified subwoofers): front left, center, and right, two standard surrounds, and an additional pair placed toward the front of the listening room, farther apart than the main left and right speakers. These last are the front-effect speakers, which emit only DSP-generated reflection signals. If your budget or decor won't allow for front-effect speakers, their signals can be mixed into the main left and right speakers, but with a distinct loss of realism in the music-processing modes.

Yamaha was the first manufacturer to introduce a multiple-echo ambience-recovery/synthesis system, and by now the company is a master of this form of sonic enhancement. The DSP-A2070 is endowed with a host of ambience-enhancement modes, many of which are said to be modeled after real acoustic spaces. For processing music there are five different concert-hall settings (based on the early-echo patterns of one American hall and four European ones), two churches (one in Tokyo and the cathedral of Freiburg, Germany), two rock-concert environments (the Roxy Theater in Los Angeles and a "Warehouse Loft"), and two jazz clubs (the Village Gate in New York City and a "Cellar Club").

As befits a home theater component, the DSP-A2070 has several modes specifically intended for enhancing audio/video program material. There are two settings for classical-music videos (Opera and Recital), two for pop and rock music, and two for TV (Mono Movie and Variety/Sports). In addition to standard Dolby Pro Logic decoding, there are five modes that can take the basic decoder outputs and subject them to a variety of added ambience effects: Enhanced Pro Logic and four "70mm" modes (Spectacular, Musical, Adventure, General).

All of these processing modes, the music- as well as the video-oriented ones-can have most of their basic sonic parameters altered and then stored as a separate user-programmed setting. With such adjustability, the potential number of settings is practically infinite.

Although the labels Yamaha has given the music modes are useful for differentiating them, it's best not to take them too seriously as application guides. It has been my experience with earlier Yamaha sound-processing devices that every mode is suitable for a wide variety of music and that the apparently classical-oriented modes can often be used with pop and rock, and vice versa. The DSP-A2070's music modes proved to be no exception, and its 70mm movie modes can also be used for music, with or without Dolby

Pro Logic sound steering. Experiment: If you don't like the results with one setting, try another. Somewhere in the amplifier is one that will work extremely well.

Still, I have always had difficulty accepting the true usefulness of any ambient-field processing beyond pure Dolby Pro Logic for the playback of Dolby Surround movie soundtracks. I have no quarrel with Yamaha's including so many options; once the DSP circuitry is there, the addition of a few more processing modes adds little to the cost of the component. Sometimes they are even fun. But while the special movie modes may make for spectacular demonstrations with carefully selected program material, they aren't as appealing in everyday use. During movies I often found myself switching out of a 70mm mode back to pure Pro Logic.

The reason for that is easy to explain. Movie soundtracks are extremely complex audio creations. The balances between front- and surround-channel sound effects, music, and the all-important dialogue are often very finely calculated. Misadjust the level for the surround speakers by just a couple of decibels, and you might have too many starships zooming by-or no apparent surround at all. Add just one artificial reflection to the signals coming from the front of the listening area, and at climactic points in the movie- when the soundtrack is at its most complex and active-the dialogue may turn into an unintelligible babble. And in its movie modes, the DSP-A2070 goes well beyond adding just one reflection.

Blurring of dialogue is precisely what I experienced with the DSP-A2070's various beyond-Dolby movie modes. Before switching back to pure Dolby Pro Logic, however, you might want to experiment with switching off or reducing the level of the front-effect signals, especially if they are being mixed into the signals to the main speakers. Again, feel free to experiment, and be glad that the DSP-A2070 has an excellent-sounding Dolby Pro Logic decoder to fall back on.

Despite the DSP-A2070's wealth of features, its front panel is remarkably uncluttered. There are four reasons for this. First, most of its few controls are hidden behind a flip-down panel.

Second, the remote control carries most of the burden of command. Third, many features are operated via display-oriented menus that require very few buttons to navigate. And fourth, the display is small-too small, in fact, and too dim to be always visible from across the room. Yamaha does, however, provide an on-screen display system that expands the front-panel readout, literally and figuratively, by superimposing menus on the TV picture-unless, I found, the picture happens to be one of those blue screens many VCR's and laserdisc players put up when there's no other video signal. I've never liked blue-screen outputs, and apparently neither does the A2070.

For all its multibuttoned complexity, the programmable remote is rather easy to use. That's because the monotony of the regular button layout is broken by a nice arrangement of the amplifier menu controls and the larger-than-usual volume buttons. Except for the power and input-selector buttons, all of the amplifier controls are on the lower half of the handset. They include everything you'll need for listening-seat adjustment of surround-speaker levels as well as an extremely useful on/off button for DSP effects that makes it easy to hear the results of mode and parameter changes.

The DSP-A2070 was one of the first components to undergo our new (and still expanding) array of Dolby Pro Logic tests. As you can see from the lab results, there was much to be measured. The A2070 did very well in every category except one, and even that can literally be adjusted to perfection. Right out of the box, the A2070's surround-channel noise-reduction calibration level was 6 dB too high (based on an expected -20-dB output of 141.4 millivolts from a laserdisc player). That would make a typical laserdisc player's output 6 dB too low for the A2070's internal level-setting of its surround-channel Dolby B noise reduction, which means that the noise reduction would kick in 6 dB too soon, possibly dulling the surround-channel sound. But adjusting the input-level trim for the videodisc input to +6 dB put the A2070 right on the mark. Unfortunately, you give up 6 dB of Dolby-decoder overload margin in the process, which might audibly affect some very dynamic soundtracks.

The A2070 also fared very well in traditional audio measurements. It is good to see the important center channel receiving so much attention and power. The amplifier had ample continuous and peak power reserves; we never ran out of juice during our listening tests. The tone controls have a nice range of operation, except that moderate settings of the bass knob had a substantial effect in the upper bass and lower midrange as well: A 5-dB cut at 20 to 40 Hz also reduced the 300-Hz level by 3 dB. The calibrations of the center-channel equalizer proved to be accurate, and it produced a maximum cut or boost of 6 dB at the indicated band-center frequencies (100 Hz, 300 Hz, 1 kHz, 3 kHz, and 10 kHz). Although I did not always find it useful for matching the sound of a center speaker to that of the main speakers, it's a good first step in ameliorating a nonideal situation.

Inveterate button-pushers should be in seventh heaven with the DSP-A2070. The music-processing modes offer such versatility that you can easily spend an entire listening session setting and resetting modes. That's good not only for didactic reasons- you can learn a lot about ambience from such experiments-but because the sonic results can be so very satisfying. Classical music can sound extraordinarily realistic, and pop music can gain immensely in vividness and movies in excitement with the right settings of the controls. The Yamaha DSP-A2070 is the only integrated amplifier that gives you such comprehensive control of such formidable processing power. Once you experience it, going back to your old two-speaker system will be a big letdown.

Yamaha DSP-A2070 AV amplifier photo