B&K AVP2000 Audio/Video Preamplifier Review

In the old days—around ten years ago—only big electronics companies could afford the production costs associated with microprocessor-controlled audio equipment. Even then, a component with an internal computer was rare. It’s a measure of the sophistication of today’s integrated-circuit designs that a small and young American electronics company such as B&K Components (no relation to the Bruel & Kjaer of microphone and test-equipment fame) can produce such a product. And that product, the AVP2000 audio/video preamplifier, takes full advantage of its onboard microprocessor.

For instance, the AVP2000 can independently control two sound systems installed in different rooms. The preamp has two sets of outputs, Zone 1 (main room or group of rooms) and Zone 2 (second room or group of rooms), and the audio and video input sources (which can be different), volume, and channel balance can be set separately for each zone. Adjustments made to one zone will not affect signals sent to the other.

The preamp also has eight memory presets in which you can store a complete set of those adjustments, plus source selection, volume, balance, and muting, for both zones, enabling you to go instantly to a particular setup at the touch of a button. In addition, each preset will record the current brightness (off, dim, or bright) of the front panel’s sixteen-character fluorescent display and, for Zone 1 only, the settings of the tape-monitor loop and the FX (signal-processor) loop. You can also name the presets (the manual gives MON FOOTBALL as an example); you can even rename the inputs if you like.

While renaming of inputs is a function available in some other components, the AVP2000 has one feature that is, as far as I know, unique: It can be made to respond to commands from practically any other component’s infrared remote control. There is a special display-menu sequence for substituting “foreign” commands for those of its own remote control. This feature can be handy if you lose or break the AVP2000’s handset or, more important, if you want to use a multi-component remote control of some sort instead of the AVP2000’s own remote.

One last unusual function is Control Out, which turns on a back-panel DC signal (12 volts at 15 milliamperes) that can be used to activate an external system or component (to drop down a video screen, for example). The desired status of the control signal is also memorized with each preset.

Other rear-panel facilities include connections for a CD player, tuner, signal processor (such as an equalizer), audio tape recorder, two VCR’s, and a laserdisc player. There is no phono input. All video inputs and outputs have both composite-video and S-video connectors, but the preamp, as usual, performs no conversion between them. The video and audio connections are widely separated from each other. That could increase cable tangling, but it also helps to isolate the video and audio signals from each other within the preamp.

The optional surround-sound decoder module, which installs inside the AVP2000, adds a separate set of line-level outputs (RCA jacks) for the front left, right, and center channels, the surround channel (left and right), and a subwoofer. The decoder’s features are available only to Zone 1, and its front left and right outputs are duplicated at the regular Zone 1 outputs when it is activated by the FX control.

Each zone is supplied with two sets of stereo RCA-jack outputs, while Zone 1 also has a set of three-prong (professional-audio) XLR balanced-output connectors. Since the principal advantage of balanced connections is superior rejection of external interference with long cable runs, I would have thought it more appropriate to have Zone 2 signals on the XLR outputs. There are no AC convenience outlets, but there are three extra RCA jacks. One, labeled IR IN, is for attachment to an external infrared receiver (B&K says that the AVP2000 is compatible with most custom-installed infrared control systems). The other two, labeled SEND and RCV, are designated “for future use.”

Given such a large number of inputs and outputs, the AVP2000’s front panel is surprisingly empty: a Vi-inch headphone jack, six pushbuttons (including power and muting), the display, and a volume knob. But the reason for the wide-open spaces is that you can operate virtually all of the preamp’s functions with just four menu-activating buttons and the “interactive” display.

The unusual volume control is a spring-loaded knob, not unlike the shuttle ring on a videodisc player. Rotate it to either side, and the volume changes by steps that vary somewhat in size but average around 1 dB. Internally, the control mechanism is a set of up/down switches.

Changing volume is not so exotic on the remote, which just has a pair of up and down buttons. The rest of the remote is similarly straightforward. In fact, it is easier to run the AVP2000 from the handset than from the front panel, because on the remote many functions (such as input or preset selection) have dedicated buttons and you don’t have to slog through the interactive display process required by front-panel operation. The handset is generally well laid out, with the buttons differentiated by size and color but not enough by spacing. It’s easy to miss the FX and Menu buttons that are used to control the surround decoder, and the labeling is hard to read in a darkened room.

Fancy switching and programmability aside, the AVP2000 is a rather basic preamp. The only real signal processing it performs is in volume adjustment and the surround functions, which include Dolby Pro Logic decoding as well as several ambience-enhancement modes. The additional modes are Cinema (same as Pro Logic but with a longer maximum surround delay), Stereo Hall (a single delayed reflection to the surrounds), Enhanced Hall (a single delay to the surrounds, center speaker on), Stereo Front/Rear (stereo signals fed to the surround speakers as well as to the front left and right), Enhanced Stereo (center speaker on), Arena (a long-delay echo for programs like sports telecasts), and Stereo (plain two-channel stereo, though you should switch the processor off altogether if you want the cleanest possible stereo reproduction).

The AVP2000’s main preamp circuits measured quite well. Its output and input overload levels, in particular, were exceedingly generous. The figures for distortion and signal-to-noise ratio (S/N) were also very good, and frequency response was superb (the variations given in the “Measurements” panel are essentially the resolution limits of our test equipment).

A note on noise: Our test reports for CD and videodisc players commonly report signal-to-noise ratios (or, better, signal-to-dither ratios) of greater than 90 dB. A preamp S/N of “only” 84.5 dB, such as I measured from the AVP2000, would seem to indicate that the preamp is adding noise to its CD output. Not to worry. If the AVP2000’s S/N were measured at input and output levels of 2 volts, corresponding to the conventional maximum output of a CD or videodisc player, rather than the 0.5-volt level specified in the EIA amplifier-test standard, it would improve by 12 dB, to 96.5 dB, about the same as that from a CD player. And that’s precisely what we measured.

The Dolby Pro Logic system also tested very well, which is attributable in part to the high-performance Analog Devices Pro Logic decoder chip used in the AVP2000’s surround module. Noteworthy were the almost spot-on THX-reference calibration of the surround channel’s noise-reduction system and the very accurate noise-reduction frequency response at all levels specified in the Dolby Pro Logic standard. THX laserdiscs and other discs with spectacular sound should deliver more accurate surround-channel frequency response over a wider range of levels through the AVP2000 decoder than through many other Pro Logic decoders.

The effectiveness of the other surround modes depended heavily on the music. On the other hand, since the Hall and Arena modes introduced only a single delayed surround-speaker ambience “reflection,” it was difficult to make them sound really awful—something all too easy to do with similarly monikered modes in some other products. I liked the use of the center-channel speaker in a couple of the modes (it helps create a firmer stereo image), and Stereo Front/Rear is a useful party mode that’s surprisingly rare in other equipment.

Even after a week-long period of orientation, however, I found the AVP2000’s surround modes somewhat cumbersome to use. That was not the fault of the complete, logically ordered, well-illustrated, and well-written manual (a must-read for this product). Nor did the lack of on-screen readouts prove a major impediment. The selected input and its volume setting are usually shown in the front-panel display, and not having to turn on a TV to determine those and other important control settings is a blessing when all you want to do is listen to music.

The principal operational problem with the AVP2000 stems from its paucity of front-panel buttons, which necessitates unwieldy multistep menu-selection processes for many functions. But even with the remote and its separate control buttons, using any of the advanced features (including Pro Logic decoding) can require a long button-pushing sequence in which it is very easy to overshoot your goal, so that you have to start the whole sequence all over again.

For example, readjusting the speaker levels during Dolby Pro Logic playback (after they have been level-matched by means of the internal test tone) requires a control sequence just to get to the speaker-balance mode. And when you get there you can’t simply turn the surrounds up or down by a couple of decibels, which is perhaps the most common adjustment you’d want to make. You can only adjust the front/surround balance, which is not quite the same thing. Outside the surround modes, things go much more smoothly, since little menu-driven interaction is required if you’re using the remote.

I also felt that the preamp's preset capabilities could be improved. It would be better if the presets didn’t memorize the volume setting (or gave you the option of not including it). Volume settings normally vary quite a bit, and if you were to accidentally memorize an unusually high one, you could get an alarming surprise the next time you selected that preset. More useful would be the ability to preset input sensitivities in order to match levels between signal sources.

One nice thing about a microprocessor-controlled product is that it is under the control of software. Changing software is usually a lot easier than changing hardware, and it can be done for equipment already in the field as well as new units coming off the line. So, over time, B&K may well smooth out some of the rough edges on its surround-processor control system. In every other respect, the AVP2000 is a terrific product, delivering excellent performance in all modes, laudable multiroom capability, and fine operation as a basic preamplifier, all at a very attractive price.

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