Kenwood KVR-A90R Stereo Receiver Review

Kenwood’s KVR-A90R stereo receiver offers some video control features in addition to its digital-synthesis AM and FM tuners and extensive audio control facilities. The amplifier section is rated to deliver 70 watts per channel into 8-ohm loads from 20 to 20,000 Hz with no more than 0.007 percent total harmonic distortion. It also carries a secondary rating of 80 watts per channel into 8 ohms from 40 to 20,000 Hz with no more than 0.03 percent distortion. The receiver comes with the RC-90 forty-two-function remote control.

Perhaps the most strikingly unusual aspect of the Kenwood KVR-A90R is its front control panel, which uses membrane keys, like those found on some calculators, instead of buttons for most of its control functions. Pushplates are used for the input selectors and the volume adjustments, which step in 2-dB increments. A direct tuning feature, supplementing the usual scanning mode, allows any station to be selected by simply keying in its frequency. If desired, the frequency can be stored in one of twenty preset memories (there are ten membrane keys, each switchable to either of two memory banks). Each preset also recalls the appropriate AM or FM band.

The blue-white and red fluorescent indicators on the large display panel show most aspects of the receiver’s operating status at a glance. In the tuner mode, the frequency is displayed in large numerals together with the band, the preset number (if applicable), the FM mode (stereo or mono), and whether manual or automatic tuning has been selected. If another input source is selected, its name replaces the frequency readout. Symbolic graphs show the relative settings of the volume and balance controls. When one of the volume buttons is pressed, the tuned frequency or input identification is replaced by numbers showing the amount of attenuation.

The display also indicates the operating status of the KVR-A90R’s built-in seven-band digital graphic equalizer and spectrum analyzer, controlled by a group of membrane keys at the left of the panel. Initially, the equalizer display consists of seven short horizontal line segments joined at the center of an amplitude scale spanning a range of ± 12 dB in 2-dB steps. Each line segment corresponds to the center frequency marked below it—60, 150, 400, 1,000, 2,400, 6,000, and 15,000 Hz. Membrane keys are used to select a frequency band for adjustment. Pressing a key causes its corresponding line segment to blink on and off, and two additional keys are used to boost or cut the response, moving the line up or down, by 2 dB at a time. Each band can be set separately to form the desired response “shape.”

The selected equalization can be inserted into the program signal path, stored in one of three preset memories, or channeled to the Tape 2 recording outputs. In addition to the three user-selectable EQ characteristics, there are two internally set curves identified as loudness and presence. The EQ display can also be switched to function as a seven-band real-time spectrum analyzer with approximately two-octave filter bandwidths. A switchable peak-hold mode briefly retains the highest reading in each band.

One or two VCR’s can be connected to jacks in the rear of the receiver. A small button marked video selects which VCR’s output will be switched through the receiver when the video input selector is pressed. The video output goes to an external monitor, and the stereo or mono audio component of the signal is channeled through the receiver’s audio circuits. A small slide switch on the rear apron can be set for stereo or mono playback, and mono programs can be enhanced by a Synthetic Stereo feature. A separate audio program from one of the receiver’s other sources can be recorded on a VCR if it is designed for audio dubbing, and both video and audio can be dubbed from either VCR to the other.

The Kenwood KVR-A90R is finished in black with its membrane keys in two shades of gray. The rear apron contains phono jacks for the various inputs and outputs, screw-binding posts for AM and FM antennas, a clip for the supplied pivoting AM loop antenna, insulated connectors for two pairs of speakers, remote-control jacks for compatible Kenwood cassette, CD, and record players, and three switched a.c. outlets. The receiver measures 16-1/2 inches wide, 12-5/8 inches deep, and 5-1/8 inches high, and it weighs about 20 pounds. Price: $490.

Lab Tests

The Kenwood KVR-A90R’s heat sinks are located inside its cabinet, and the cover above them became quite warm during the hour-long preconditioning at one-third rated power, though it became only slightly warm in normal operation. With both channels driving 8-ohm loads at 1,000 Hz, the output waveform clipped at 90 watts per channel. The 4-ohm power output was 85 watts, and the output into 2 ohms was 128 watts (a protective relay turned off the amplifier before it clipped in the last measurement).

As usual, we based our tests on the EIA amplifier test standard, using the prescribed gain settings. Our distortion readings were slightly higher than the rated 0.007 percent at most frequencies and power outputs, Kenwood’s test data for our sample actually showed much lower distortion readings, and when we set the receiver’s gain to maximum, the distortion was typically from 0.002 to 0.005 percent. Lower distortion at high gain is a common effect with electronic volume controls. Our higher distortion readings, evidently caused by nonlinearity in the preamp, had little to do with the receiver’s power output.

The 1,000-Hz distortion into 8 ohms decreased from about 0.05 percent at 0.1 watt to about 0.007 percent in the 7- to 15-watt range, rising to 0.0125 percent at 80 watts before the amplifier clipped. The distortion curves with 4- and 2-ohm loads were similar. Into 8-ohm loads at the rated 70 watts as well as at half and one-tenth rated power, the distortion was a constant 0.01 to 0.013 percent from 20 to 5,000 Hz, rising to only 0.035 percent at 20,000 Hz.

The equalizer’s control range was approximately ± 12 dB, with center frequencies as indicated. Though the system is not as convenient to use as standard tone controls, the ability to store three sets of response curves for instant recall is a strong advantage. The loudness contour was very moderate in its effects—a boost of about 5 dB at 60 to 70 Hz and 2 dB at 20,000 Hz—and did not vary with the volume setting. It produced pleasing results, however, and never created an unnatural sound quality. The presence contour was even more subtle, increasing the overall gain by about 1.5 dB across the frequency spectrum, with an additional 2.5 dB in the 1,000- to 3,000-Hz range. It added a perceptible but listenable “forwardness” to the sound.

The phono section’s RIAA equalization was among the most accurate we have measured, with an overall variation of about 0.5 dB from 20 to 20,000 Hz. We also made limited measurements on the stereo synthesizer, which is usable only with mono inputs through the VCR jacks. The response of the left channel was unchanged, down 1.5 dB at 20 Hz and 3 dB at 20,000 Hz, and the right-channel output varied smoothly from about +1 to — 5 dB over the same frequency range. The phase relationship between the two channels varied continuously with frequency, however, from being in phase to 90 degrees out of phase to reverse phase and so on through several complete cycles between 20 and 20,000 Hz.

Although the FM tuner section fell slightly short of meeting its usable-sensitivity rating, it did achieve the more important 50-dB quieting specification in both mono and stereo. The tuner noise level was very low in mono for inputs above 45 dBf (100 μV) and in stereo above 65 dBf (1,000 μV), at which levels the distortion readings were very similar for both modes. The channel separation was unusually uniform, between 35 and 38 dB from 50 to 15,000 Hz. The 0.8-dB capture ratio was outstanding, as was the 75-dB AM rejection. Although we were disappointed in the image-rejection measurement of only 38 dB, it matched the manufacturer’s rating. Selectivity, though only fair, also met spec.

Comments

The Kenwood KVR-A90R is moderately priced and replete with unusual features, many of them potentially very useful. The RC-90 remote control is convenient, too, especially if you have or are considering other Kenwood components. About 30 percent of the remote is devoted to functions of the compatible Kenwood turntables, cassette deck, and CD player that can be integrated with this receiver.

To Kenwood’s credit, the KVR-A90R is not advertised as an audio/video receiver, as we have seen done for other products with very similar features. Its video capability is strictly limited to signal switching between a couple of VCR’s and a monitor, enhancing a VCR’s mono sound with the Synthetic Stereo circuit, and amplifying a video-derived audio signal for playback through a stereo audio system.

The audio section is actually very good, and certainly powerful enough for most reasonable needs in an audio/video system. Also, even though the amplifier is not rated for use with very low speaker impedances, it does a very creditable job in that respect as well. The utility of the graphic equalizer depends on your own listening habits and preferences. It is certainly capable of creating a wide variety of response curves, and the EQ-memory feature could be a great convenience. Even the loudness and presence contours are reasonably chosen.

The spectrum analyzer conveys little more information than your own ears can provide, but it does no harm. We noted, incidentally, that the analyzer’s sensitivity is fixed and not necessarily related to any signal level under the user’s control. In other words, it can easily be driven to the top of the scale (and off scale) at modest levels, making its value questionable.

The FM tuner section’s performance, though generally quite good— and nothing less than outstanding in capture ratio and AM rejection— is marginal in respect to image rejection, but unless you live close to a major airport, this might not be a real problem. The AM tuner’s quality is typical of that provided by stereo receivers.

In short, the overall performance of the KVR-A90R, though not exactly outstanding, is certainly adequate. Any criticisms of the receiver should be viewed in relation to its price. While not inexpensive, it is not a high-priced component by today’s standards, and it is attractive, functional, and versatile.

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