Rockford Fosgate RF-2000
Thirty-two MOSFETs, a thousand-volt-amp toroid, and a fan you'll never hear. The Arizona car-audio house's first serious bid for the audiophile rack.
Overview
The RF-2000 is heavy in a way that tells you where the money went. It weighs thirty-five pounds, in a chassis 17½ inches wide by 4½ high and 13 deep. Most of that mass is a 1,000-VA toroidal transformer and a pair of 42,000-µF storage capacitors, a low-impedance current reservoir meant to survive musical transients and speaker loads that swing all over the map. Rockford Fosgate rated it at 200 watts per channel into 8 ohms across the full 20 Hz to 20 kHz band, 300 watts per channel into 4 ohms, and 600 watts bridged into an 8-ohm load. Rated THD was 0.05% at 8 ohms and 0.1% at 4, with IM distortion at 0.01% and 0.02% respectively. Slew rate was quoted at 80 V/µS and signal-to-noise at 110 dB referenced to full power. Audio (June 1990, p.83) reproduced those figures in its equipment profile. The same issue's bench work found the amp's dynamic headroom was 2.44 dB into 8 ohms, enough to punch out roughly 350 watts per channel on peaks.
The output stage is the headline. There are thirty-two MOS-FET devices, sixteen per channel, each rated at 4.0 amperes continuous drain at 100° C. The amp is fully rated for 8- and 4-ohm loads and stays stable down to 2 ohms. Protection works by analog computing. Device temperature is continuously calculated against a maximum limit, and if the amp reaches that limit it cuts back automatically and the affected channel's front-panel LED turns red. A pair of thermistors, one per heat sink, measures the input system's temperature, controls fan speed, and triggers thermal shutdown when things get genuinely unsafe. The cooling fan is continuously variable and, by all accounts, extremely quiet. High Fidelity (July 1989, p.27) noted it never came on during that magazine's listening tests, only during high-power bench measurements, and that a servo mechanism keeps it from suddenly firing up. Audio's reviewer, running the amp for extended listening, reported never being bothered by it either.
What separates the RF-2000 from a straight two-channel box is its operating flexibility. It has four modes. Normal stereo is the first. Bridged mono gives higher power. Dual mono drives both channels from the same input signal, useful for biamping a speaker with separate high- and low-pass inputs. The fourth is a stereo-plus-bridged configuration that drives a pair of satellites and a bridged mono subwoofer or center channel from one chassis. The rear panel has left and right input jacks, each with its own gain control adjustable from 0 to 36 dB, color-coded five-way speaker terminals, and individual 5-ampere fuse holders for speaker protection. Mode switching is done by pushbutton, so no internal rewiring is needed. The front panel carries a three-LED multicolor status display per channel. It is dark below about 200 mW of output, green above that so long as distortion stays low, and red when the signal distorts. A separate power LED reads green in normal operation and red when overheat protection engages.
According to the period coverage, the RF-2000 was the first in a series of high-performance audio components from the Tempe, Arizona manufacturer, which had built its reputation in the professional audio field. Audio (June 1990, p.83) noted the home amp is similar in most details to the company's PRF2000 professional model. The chief difference is the input arrangement. The pro version permits balanced or unbalanced operation with XLR or phone-jack terminals, while the home version uses standard RCA phono jacks. Original price was $1,250. A companion RF-200 preamplifier, which Audio tested in the same issue, was priced at $575.
On the bench the amp behaved itself. Audio (June 1990, p.90) described it as remarkably stable and reliable, impervious to failure no matter how hard it was driven. The reviewer popped speaker fuses during testing but never once saw the amp shut down for thermal or any other reason. High Fidelity (July 1989, p.27) measured an extremely high 50 Hz damping factor, evidence of very low output impedance, and described everything about the amplifier as suggesting careful thought and solid design. Listening tests paired it with KEF 105/2 reference loudspeakers and a Sony CDP-650ESD player. Organ recordings and small-ensemble Mozart symphonies came through without strain even in deep bass passages. The reviewer's verdict on the price was that the $1,250 tag had looked a bit high going in, but the total cost of amp and preamp together came in about where it belonged.
For collectors, the RF-2000 is a car-audio company's first home component, built with seriously good parts - the toroid, the MOSFET count, the analog-computing protection - and reviewed favorably by the magazines that mattered at the time. The practical caution is the speaker fuses. Audio's tester found it necessary to substitute higher-amperage fuses to conduct rated-power tests. That means the stock 5-ampere protectors are conservative and will blow before the amp will. That's a design choice, not a fault, but it helps to know before someone concludes the amplifier is cutting out. Units surface rarely enough that pricing is best established by watching completed sales rather than asking prices.
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