Nakamichi AV-1 AV-receiver
The AV-1 is Nakamichi's most powerful audio/video receiver. It contains an AM/FM digital frequency-synthesis tuner, a preamplifier, digital signal processing (DSP) circuits for simulating several acoustic environments, and five power amplifiers. The AV-1 has complete signal-switching facilities for selecting and controlling tuner, CD, and phono sources, two audio tape decks, two VCR's, and a videodisc player, including inputs and outputs for both composite-video and S-video signals.
The front (main) power amplifiers are rated at 100 watts per channel into 8 ohms from 20 Hz to 20 kHz, both channels driven, with less than 0.1 percent total harmonic distortion (THD). A switch on the rear of the receiver enables safe full-power operation into 4-ohm loads. The surround-channel amplifiers are rated at 30 watts apiece, and the center-channel amplifier is rated at 50 watts, all at 1 kHz into 8 ohms with no more than 0.1 percent THD.
The AV-1's large front-panel volume knob is driven by a motor when operated from the supplied remote control. The receiver's only other control knob is a small input-balance adjustment for setting up the Dolby Pro Logic decoder. All other operations, including station selection, audio level, tone-control adjustment, and the like, are done with pushbuttons.
The AV-1's front-panel display window shows its complete operating status. The tuned frequency, preset channel number, and station call letters (when programmed by the user) appear in large orange characters against a black background. Smaller red or orange characters show the signal-processing mode, tuner status and relative signal strength, and tape (audio and video) source and dubbing path where applicable.
Below the window, a row of large pushbuttons selects the program source and dubbing configuration. The Source Direct button bypasses all surround and response-modifying circuits, routing the selected program through the volume control and directly to the front-channel power-amplifier sections.
Below the source selectors, a group of smaller buttons controls the receiver's four spatial-modification circuits. These include Dolby Pro Logic for compatibly encoded video or audio programs and three synthesized environments identified as Natural, Hall, and Stadium. The Hall environment simulates the effect of a typical concert hall by adding reverberation to the delayed signals supplied to the surround speakers. Stadium provides longer delays and more reverberation, whereas Natural (for use with programs containing considerable reverberation) adds mainly an array of discrete signal delays rather than reverberation.
Other buttons control the Surround Memory function, which enables the user to program aņā store as many as four different sets of spatial parameters for later recall. This is done with the previously mentioned spatial-modifier buttons, which are also numbered 1 through 4. In addition to its normal function, each button can be used to store one set of user-selected parameters, retrievable by pressing the Memory Call button. The adjustable parameters include the level of each channel, delay time (from 10 to as much as 150 or 250 milliseconds, except for the Pro Logic mode, which is limited by Dolby specification to a range of 15 to 30 milliseconds), and tone-control settings.
The tone-control, level, and delay adjustments are performed with a single pair of up/down buttons and a group of small selector buttons, marked Center Level, Rear Level, Delay, Balance, Treble, Bass, and Super Bass. The up/down buttons adjust the value of a selected function in ten steps for each of the tone controls and nine steps for the full range of the balance adjustment. The delay can be adjusted in 10-millisecond intervals. The treble and bass tone-control ranges are typical of modern receivers, but the Super Bass feature is unusual and convenient, cutting in about an octave lower than the main bass control. A small loudness-compensation button is located near the volume knob.
Other front-panel features include the tuning buttons, small adjacent buttons that select AM or FM and automatic stereo switching with interstation muting or mono FM reception without muting for weak signal reception. A grid of small buttons is used for storing as many as thirty AM or FM channel presets or for direct numerical tuning to any frequency. These buttons can also be used to add your own five-digit alphanumeric identifier to each preset memory, which will be displayed when that preset is selected. At the lower left of the panel are a stereo headphone jack, separate speaker-switching buttons for two pairs of front speakers and the surround and center speakers, and the input-balance knob for the Dolby Pro Logic decoder.
The AV-1's rear apron contains input and output jacks for all potential source components and recorders, plus composite- and S-video monitor outputs. There is also a separate preamplifier output and power-amplifier input (joined by a removable link) for each channel, along with a monophonic preamplifier output that could be used to drive a powered subwoofer.
Insulated binding posts are provided for the two sets of main front-channel speaker outputs, and spring-clip connectors (for stripped wire ends) are used for the center and surround speakers. Although the main-channel binding posts superficially resemble the five-way connectors used on many amplifiers, they accept only wire ends and cannot be used with banana plugs or most types of lugs.
Antenna terminals are provided for the included AM loop antenna, along with a 75-ohm coaxial jack for an FM antenna. There are two switched AC outlets and a slide switch that selects for high- or low-impedance speakers.
The AV-1's FM tuner section was very good in many respects, but less so in others. For example, its capture ratio, AM rejection, and selectivity were well above average. On the other hand, image rejection was marginal, and though the mono FM performance was quite good, full quieting in stereo required an unusually high signal level of 70 or 80 dBf. FM distortion was also higher than we usually find in top receivers and tuners. Stereo channel separation, very good in the important midrange, remained a good 35 dB or better over the rest of the audio range. The AM frequency response, like that of most receivers, was mediocre.
The amplifier section's audio frequency response was excellent. At the preamplifier outputs, the front-channel response was flat within +0, -0.3 dB from 10 to 25,000 Hz and down 3 dB at 90,000 Hz. Although the basic tone-control curves were conventional, the Super Bass feature added a worthwhile measure of extra control in the lower bass (from 100 Hz to 20 Hz or below). In particular, the +4-dB setting might partially compensate for the low-bass rolloff of many small speakers. The loudness-compensation contours were typical, with a moderate low-frequency boost and a smaller high-frequency boost at most usable volume-control settings.
The main power amplifier was conservatively rated, with output into 8 ohms at 0.1 percent distortion of about 130 watts per channel from 50 Hz to 20 kHz and 115 watts at 20 Hz. Performance was essentially identical when we used 4-ohm loads with the switch on the rear apron set for 4-ohm operation. We also tested the amplifier into 4-ohm loads with the switch at its 8-ohm position (because the impedance of most "8-ohm" speakers drops to much lower values at some frequencies) and measured an impressive 180 watts per channel from 100 Hz to 3 kHz, decreasing only slightly to 173 watts at 20 kHz and 160 watts in the 20- to 30-Hz range.
The surround-channel amplifiers were rated with similar conservatism. Into 8 ohms, they delivered about 37 watts at 0.1 percent distortion into 8 ohms from 70 Hz to 20 kHz, with output decreasing to the rated 30 watts at 20 Hz. The center-channel power output was about 64 watts from 90 Hz to 20 kHz and 52 watts at 20 Hz. The AV-1 also has an unusually good phono section for an A/V receiver, as evidenced by its healthy overload margin and the flatness of its measured frequency response, down only 0.05 dB at 40 Hz and 10 kHz, 0.2 dB at 25 Hz and 20 kHz, and 0.4 dB at 20 Hz.
The AV-1's remote control not only duplicates almost all the receiver's front-panel controls but has sections dedicated to compatible Nakamichi tape decks and CD players as well. It is also a "learning" controller, programmable to operate similar system components from other manufacturers. Although the controller has a total of sixty-three buttons, they are well spaced, logically grouped, and clearly marked to match the receiver's panel nomenclature.
Like all A/V receivers, the AV-1 is a fairly complex device, and some practice is needed to obtain best results. The instruction manual explains the control functions clearly, but there is no substitute for hands-on experience to achieve the kind of performance you paid for.
We used the AV-1 in a full five-channel configuration, which was very easy to set up and balance from the listening position thanks to the excellent remote control. The three basic DSP environments, plus the available modifying adjustments, provide ample capability for creating almost any sound character you wish. If you are disturbed by an inability to recreate the sound of your favorite seats in your favorite concert hall, there are three possible solutions: (1) Buy season tickets to the live concerts (a good idea in any case), (2) invest many times the price of the AV-1 in a state-of-the-art system including an advanced DSP processor and correspondingly advanced speakers (which may sound great but still won't be indistinguishable from the real thing), or (3) take the time to set up the AV-1 carefully with five reasonably good speakers and other appropriate system components, sit back, and enjoy the music. I don't think you'll be disappointed!
