Yamaha DSP-A1000 Audio/Video Amplifier Review

The DSP-A1000, which Yamaha calls a Digital Sound Field Processing Amplifier, requires only the addition of signal sources and loudspeakers to serve as the core of a versatile audio/video (A/V) system. It combines refined digital signal-processing circuits, a preamplifier providing switching and control facilities for both audio and video sources, Dolby Pro Logic surround-sound decoding, and no fewer than seven channels of audio amplification.

The DSP-A 1000’s Dolby Pro Logic system uses digital circuitry, with an automatic input-level balance control that maintains optimal surround-sound settings without user attention. It also has an “Enhanced” Dolby Pro Logic mode said to create a sound field typical of a standard (35-millimeter) movie theater. When this mode is used with the amplifier’s Movie Theater DSP program, according to Yamaha, it re-creates the broader sound field typical of a 70-millimeter theater. Another special feature is a “directional enhancement” circuit that can be used with the Concert Video and TV Theater DSP modes to give the listener a sense of being in the midst of the audible action without making it sound detached from the screen.

Despite its considerable versatility, the DSP-A1000 is surprisingly simple to install, set up, and use. In normal operation, the front panel has only two visible knobs (volume and the input selector), a power pushbutton, a tape-monitor button (labeled tape 2), and a small LCD window. The input sources are identified as auxiliary, VCR 1, VCR 2, TV, LD (laser videodisc), DAT/Tape 1, tuner, CD, and phono.

Opening the hinged door that extends across the bottom of the panel reveals three small knobs (bass, treble, balance) and a REC OUT rotary switch that enables the user to record audio or video programs from any source independently of the one being heard or seen.

Several narrow bar switches, labeled SET MENU, INPUT TRIM, EFFECT, and PROGRAM, provide a wide range of control over the DSP-A 1000's digital signal-processing parameters. Their settings, and those of other operating controls, are shown in the front-panel display window or on the screen of a video monitor connected to the amplifier’s video output. Also behind the hinged door are a headphone jack, a bass extension button, and auxiliary composite-video, audio, and S-video inputs for connection of a camcorder or other temporary program source.

The seven power amplifiers in the DSP-A 1000 include the main (left and right) front channels, rated at 80 watts each into 8 ohms from 20 to 20,000 Hz with no more than 0.015 percent total harmonic distortion plus noise (THD + N), a center front channel with a similar rating, a pair of front channels rated at 25 watts from 20 to 20,000 Hz into 8 ohms at 0.05 percent THD + N, and a similar pair of rear effect channels. The amplifiers are also rated to drive 6-ohm loads, with power limit^ of 100 and 30 watts per channel for the main and center and the effects channels, respectively.

The rear apron has phono jacks for the inputs (and outputs, where applicable) of all sources, plus the video-monitor output. All video circuits are also provided with S-video jacks. Insulated binding posts for all speaker outputs accept dual banana plugs or stripped wire leads. The center-channel speaker outputs can be switched to drive either a single speaker or a pair. Preamplifier outputs for the main and center channels can be separated from their respective power amplifiers by removing jumper plugs. There is a line-level mono (full-range) output and an adjustable line-level subwoofer output (below 200 Hz) as well as front and rear efifects-channel line outputs for driving external amplifiers. Two of the three AC outlets are switched.

The DSP-A 1000 comes with a Yamaha RCX remote control that can operate virtually all of its many functions. In fact, the RCX controller should be used from the listening position to adjust the DSP and other parameters for the desired effect, with the display of menus and control options on the TV screen as a guide (the same information is also shown in the DSP-A 1000’s front-panel window, but it is readable only at fairly short distances). Both the volume and input-selector controls are motor driven when operated remotely, with red LED index marks to show their settings at a distance.

The RCX remote control is also preprogrammed to operate compatible Yamaha tuners, tape decks, VCR's, videodisc players, CD players, and DAT decks. The control buttons are grouped and colored according to their functions to minimize confusion. In addition, the RCX can learn the basic infrared command codes for most other audio and video components that might be used in a system with the DSP-A1000. (We found that it learned the play and pause/stop commands for a couple of CD players but would not operate their search and track-skipping functions.)

The Yamaha DSP-A 1000 is, not surprisingly, a large and fairly heavy amplifier. It measures 17-1/8 inches wide, 18-1/2 inches deep, and 6-3/4 inches high, and it weighs 44 pounds. Price: $1,499.

Lab Tests

Since direct access to the DSP-A1000’s effects channels, without going through its internal digital circuits, would require making alterations to the circuit boards, we limited our amplifier measurements to standard tests of the main left and right channels.

With both channels driving 8-ohm loads at 1.000 Hz, the main amplifiers clipped at 134 watts output, corresponding to a clipping-headroom rating of 2.2 dB. The dynamic output into 8 ohms was 156 watts, corresponding to a dynamic headroom of 3 dB, and increased to 242 watts into 4 ohms. With a 2-ohm load, the amplifier’s protective system shut it down on the 20-millisecond tone bursts of this test. Harmonic distortion at 80 watts (8 ohms) was 0.015 percent over most of the audio range, with a maximum reading of 0.025 percent at 20,000 Hz.

Frequency response of the main channels was +0, -0.5 dB from 20 to 20,000 Hz. The Bass Extension circuit increased the output below 200 Hz to a maximum of +5.5 dB at 70 Hz, with a steep (15-dB-per-octave) cutoff below that frequency. The bass tone control operated below 400 Hz, producing a maximum boost or cut of 10 or 11 dB at 20 Hz. The treble-control curves were hinged at 3,000 Hz, with a maximum range of ± 11 or 12 dB at 20,000 Hz.

The RIAA phono-equalization error was a maximum of +0.3 dB at 32 Hz and -0.8 dB at 20,000 Hz. Phono-input impedance was 48,000 ohms in parallel with a 230-picofarad (pF) capacitance. The phono input overloaded at 1,000-Hz-equivalent levels of 113 to 148 millivolts (mV) between 20 and 20,000 Hz.

Sensitivity, for a 1-watt output into 8 ohms, was 20.5 mV through the CD input and 0.22 mV through the phono input. The respective A-weighted noise levels were —81 and —77.5 dB, referred to a 1-watt output.

Comments

Considering only its basic amplifier functions, the DSP-A 1000 is an exceptionally full-featured, versatile component that performs very well in respect to output power, distortion, and noise. Its most important functions, however, involve its DSP capability. Its digital memories contain the data needed to re-create the sound-field characteristics of twelve basic acoustic environments. Since eleven of these selections provide a pair of options, the user has a choice of twenty-three preprogrammed acoustic environments at the touch of a button. One of the options, for example, puts the listener either in a fairly live concert hall or on the stage, surrounded by the orchestra. Similar options are offered for the Concert Video, TV Theater, and Movie Theater Environments. The instruction manual, which is thorough and easy to follow, includes descriptions of the various simulated sound fields, including such information as the size and acoustic treatment of the particular concert hall, disco, etc., that each one is based on.

Most of the preprogrammed environments can be modified by the user to suit his taste. Typical variable parameters are the initial delay time, the size and liveness of the room, and the upper frequency limit of the effects channels. The basic Dolby Pro Logic surround mode’s standard 20-millisecond (ms) delay is adjustable to as much as 30 ms in steps of 1 ms. The optional Enhanced Pro Logic mode increases apparent sound-field width and adds room-size and room-liveness adjustments.

We used the Yamaha DSP-A 1000 for a limited time in a home theater installation that utilized all seven channels of audio, with a videodisc player as the program source. Over a more extended period, we used it in a six-channel system with audio program sources only.

The subjective results were, to put it succinctly, superb. Every sound-field enhancement system that has been introduced, from the earliest, relatively simple rear-channel delay systems to the DSP-A1000, has required care in speaker placement and setup adjustments to obtain the best results. With the DSP-A1000, however, we obtained a reasonably believable simulation of the nominal acoustic environments without undue difficulty.

That does not necessarily mean that you can use it to re-create any programmed concert hall in your living room. The audio art has a considerable way to go before that will be possible. But you can add a considerable degree of realism to most recorded program material with the DSP-A 1000. The sophistication of its DSP circuits reflects the current state of the art in consumer products, and it is very good indeed.

With video material, and especially if the speakers are well chosen and located, the DSP-A 1000 can provide the sort of surround involvement you’d expect from a good movie-theater installation. And its all-in-one design makes that result possible without the complication of connecting and installing several components and adjusting them to make their levels compatible. The Yamaha DSP-A 1000 does it all in one manageable unit at a price comparable to that of the first generation of digital signal processors. A very impressive piece of equipment.

Read all

Yamaha reviews

Read all