JVC R-X500B (1984)
A $650 receiver with a front panel so busy it borders on overwhelming - and nearly every button earns its keep.
Overview
The first thing anyone notices about the JVC R-X500B is the display. Audio (December 1984, p.51) called it "the most elaborate looking front panel I have ever seen." The reviewer admitted that he'd normally criticize such a flashy, video-graphics-like display, but concluded this one clarifies the receiver's features rather than decorating them. It's a 1984 top-of-line JVC receiver that looks like a computer terminal and largely behaves like one, thanks to an advanced microcomputer running both the tuner and the equalizer.
The amplifier is rated at 100 watts per channel, minimum RMS, both channels driven into 8 ohms, from 20 Hz to 20 kHz, with no more than 0.007% total harmonic distortion. That's a conservative spec sheet, and the bench numbers back it up. Audio (December 1984, p.56) measured nearly 110 watts per channel into 8-ohm loads before clipping. At the rated 100 watts the THD for a 1 kHz signal came in at roughly 0.002%, so low the reviewer had to set up his spectrum analyzer specially to read it. At rated output, THD measured about 0.0045% for a 20 kHz test signal and 0.005% at 20 Hz.
The tuner section is a quartz-synthesized digital design governed by that same microcomputer. It stores 15 AM and 15 FM presets for one-touch recall. A "Preset Scan" function samples every stored station for about five seconds each so you can decide what to lock in. Instead of a needle or a bank of LEDs, the R-X500B reads out actual signal strength in dB above 1 µV, in 5 dB increments. JVC's own literature (reproduced in Audio, September 1984, p.23) billed the arrangement as "a tuner as smart as a computer," which is marketing. The independent measurements were strong, though: 50 dB quieting sensitivity at 14.8 dBf in mono and 38.3 dBf in stereo, S/N of 82 dB mono and 73 dB stereo, and capture ratio of 1.5 dB.
The tone control section is where the R-X500B departs hardest from convention. There are no bass and treble knobs. Instead there's a seven-band graphic equalizer, which JVC calls "SEA," for Sound Effects Amplifier, with center frequencies at 63, 160, 400, 1k, 2.5k, 6.3k, and 16 kHz and ±10 dB of control range on each band. The bands are adjusted electronically with Up and Down buttons rather than sliders, and five complete response curves (plus their inverse curves) can be memorized for instant recall. Audio (December 1984, p.51) noted this was the first receiver the reviewer knew of that altered band settings electronically at the touch of a button, and the first to store multiple equalizer responses. In normal use that same display section doubles as a real-time spectrum analyzer. The reviewer's scope photo of the equalizer's full control range showed filter spacing "as accurate as any I have encountered during tests of separate, dedicated graphic equalizers."
A wireless remote is supplied, and it's more than a volume-and-mute affair. It adjusts channel balance, volume, and program source, calls up preset AM or FM stations, and even adjusts the graphic equalizer or selects any stored response setting. The rear panel carries the expected input and output jacks, 75- and 300-ohm FM antenna terminals plus an external AM antenna connection, twin speaker outputs, AM/FM channel-spacing switches for U.S. versus European spacing, a pair of AC convenience outlets, and a DIN connector for a tape-monitor loop. A separate AM loop antenna is packed in and pivots away from the chassis on the rear panel for best AM reception.
The phono stage has both moving-magnet and moving-coil inputs. The MM input measured a signal-to-noise ratio of 84 dB referenced to a 5 mV input and 1 watt out, which the reviewer called "very outstanding." The MC input, referenced to 0.5 mV, managed 69 dB. High-level inputs hit 89 dB referenced to 1 watt. Run the arithmetic on a CD player feeding peaks within 3 dB of rated output and the system delivers a total dynamic range of about 106 dB. The RIAA equalization is specified at ±0.5 dB across 20 Hz to 20 kHz.
There's one quirk. The QSC (Quieting Slope Control) circuit is a blend circuit that reduces noise on weak FM stereo signals while keeping separation at still-acceptable levels. Audio (December 1984, p.56) found that once QSC engages, it doesn't shut off when the station's strength increases again, and there's no direct way to defeat it. The only workaround is to tune away and tune back.
The amplifier itself uses JVC's Dynamic Super-A circuitry, which the company says combines Class-A and Class-B virtues: the output transistors never switch off, so no switching distortion is generated, while efficiency stays closer to Class-B. A second JVC circuit, the Gm Driver, drives the power stage at constant voltage to lower output impedance and flatten frequency response, countering the back-EMF a speaker load throws at the amp. JVC's advertising made much of both.
Damping factor is specified at 45 into 8 ohms. Dimensions are 17-1/8 inches wide, 4-5/8 inches high, and 14-9/16 inches deep. The metric equivalents in the manufacturer's spec sheet read 43.5 cm × 11.7 cm × 37 cm, and the receiver weighs 20-1/2 pounds (9.3 kg). Power draw is listed at 350 watts (450 VA) on 120 V, 60 Hz. The front panel is finished in black with graphics and lettering ranging from yellow through orange to brown. JVC also offered a lower-powered sibling, the R-X400, at 70 watts per channel with a silver-and-black front panel. It resembles the R-X500B in all respects except that its moving-coil phono input.
At $650, Audio (December 1984, p.56) closed its review with "unqualified approval and recommendation," calling it "this true bargain receiver." The reviewer noted that a standalone microprocessor-controlled graphic equalizer with response storage had cost more than $2,000 when first introduced as a separate component, and that the first frequency-synthesized tuner with presets he tested memorized five stations and cost around $2,000. The R-X500B gives you both facilities, plus 30 total tuner presets, in one $650 box. There are a lot of buttons, and the reviewer admitted the receiver takes some getting used to.
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