Krell KAV-300R
A 150-watt-per-channel stereo receiver from a company that built its reputation on separates.
Overview
The idea of a Krell receiver struck Audio magazine's reviewer as something like a "Porsche minivan" or a "Hasselblad camcorder." It went on the publication's unofficial list of Things We Thought We'd Never See. Yet there it sat on the test bench: a 150-watt-per-channel, analog-input/output, remote-controlled AM/FM stereo receiver. Once the shock wore off, the logic was easy to see. The KAV-300R is Krell's own KAV-300i integrated amplifier, already well regarded in high-end circles, with an AM/FM tuner section added. Krell's own framing, as quoted in the review, was that the receiver gives the audiophile an exceptional two-channel music system in a convenient package that can stand alone or slot into a larger multi-component setup.
What separates this from the flood of high-power receivers that crossed the Atlantic between 1965 and 1985 is the execution. Audio (September 1999, p.75) described it as massively constructed and finished with a precision and care simply not found in the superstore aisles, which is what one should expect from an esoteric maker. The chassis pan is folded from 2-millimeter steel sheet, as are the top and rear wraparound panels. The front is Krell's trademark milled-billet aluminum fascia in gray-flannel anodizing. The hefty toroidal transformer is internally shielded, and the interior heatsinks are finished more carefully than some amplifiers' exterior ones. Three heavy glass-epoxy circuit boards carry tight-tolerance resistors, upmarket capacitors, and mostly discrete transistors. A scattering of ICs handles control and switching chores only. Twelve output transistors appear to serve each channel, stamped "Krell" above their Motorola logo and described as proprietary. A cookie-tin-sized shielding can in the front-right section houses the tuner module, marked as designed and manufactured for Krell by Day/Sequerra. That is an impeccable RF pedigree on paper.
The rated power is 150 watts per channel into 8 ohms, both channels driven, from 20 Hz to 20 kHz, at 0.06% THD. The measured numbers were more generous. Audio's bench tests (September 1999, p.78) found the Krell delivered its rated watts easily and produced a measured 240 watts per channel into 4 ohms with both channels driven, along with a useful 2.3 dB of dynamic headroom into 8 ohms and slightly more at 4 ohms. The magazine noted that Krell rates the receiver's 4-ohm output for one channel driven, which lines up with the both-channels 4-ohm figure observed. Frequency response was almost perfectly flat, channel-to-channel tracking was tight, and channel separation sat close to 70 dB or better at any frequency. Signal-to-noise came in around 84 dBW, A-weighted, described as truly excellent. Factoring in the headroom gives a dynamic potential approaching 110 dB. The 120-Hz hum component was the only notable feature in the noise spectrum, more than 90 dB down in both channels.
One bench result ran against type. THD+N versus frequency came in a bit higher than most conventional solid-state amps: around 0.3% at 1 watt output, which is roughly as specified, and nominally 0.1% at 150 watts. The reviewer's educated guess was that the "high" distortion, still far below audibility, comes from a higher-biased operating mode that keeps the amp closer to Class A well above the 1-watt level. The 150-watt curves show fully Class-AB operation. Damping factor was the other oddity: greater than 20 at low frequencies (output impedance around 0.25 ohms), slightly higher at mid frequencies (about 32), and back to around 20 at 20 kHz. That's low by modern solid-state standards. The reviewer had no immediate explanation beyond a suspicion that Krell's proprietary output devices impose a higher-than-typical output impedance. In practice, a system built around the 300R should hold real-world frequency response well within 0.5 dB as long as speaker-cable resistance stays low and runs stay short. No loss of control or floppy bass was heard.
The receiver is simple enough that the owner's manual is nearly superfluous for basic operation. Pushbuttons handle all control functions - source selection, tuner operation, even volume up/down - and a large blue display supplies tuner mode information, tuning, and signal-strength data. There are four line-level inputs, one on balanced XLR jacks and three on unbalanced RCAs, plus a complete tape loop and the on-board tuner. Output is via five-way binding-post pairs for each channel, solidly panel-mounted. The power cord is a removable IEC type. There's also a single 12-volt trigger and a jack for Philips RC-5 hardwired remote commands, which help with integration into more elaborate systems. The one concession to the A/V age is "Theater Throughput." Hold any input's selector key for four seconds and that input's signal passes at unity gain straight to the power-amp section. That lets the receiver drive the main left/right pair of a multichannel system from a surround processor's line outs.
The tuner is the weak spot. Audio (September 1999, p.78) found FM performance adequate but called the AM section more than a little disappointing. With the supplied indoor dipole, reception was barely better, if at all, than a typical modern table radio, and that held across four trials on four different days. The reviewer's blunt question was why include an AM section at all. For background music, news, weather, or a ball game on strong urban and suburban signals, the tuner does its job.
The amplifier side is where the KAV-300R earns its keep. Audio (September 1999, p.75) judged the amplifying abilities faultless, noting the receiver equaled the reviewer's usual pre/power-amp combo in sound while occupying roughly one-quarter the cubic volume. Through small, low-sensitivity two-way speakers, the Krell produced effortlessly timbre-defined lower octaves even on pianissimo passages. The top end was open, airy and non-forward, which the reviewer simply didn't hear on all but a very few receivers, amplifiers included. Janáček's Lachian Dances (Reference Recordings RR-65CD) sounded superb, with deep, quiet backgrounds from which the music built in intensity. The Sinfonietta's opening fanfares came through punchy and clear, free of congestion or harshness, with reserves left for the timpani entrances. On the Jim Hall & Pat Metheny duo disc (Telarc CD-83442), the close-miked acoustic guitar carried an excitingly real pressure wave on each accented downstroke. The receiver was spectacularly quiet, with not one molecule of audible noise at any sane volume, even at midnight. Randy Newman's Bad Love, with its heavy 40-Hz bass and ultra-loose bass drum, was delivered at high levels without loss of control on a somewhat difficult speaker load, while delicate Dobro definition stayed intact.
At $3,450, it was a lot of money for a stereo amplifier, however capable. The counter-argument, as Audio framed it, is that superbly musical power plus an internal radio, basic preamp functions, Theater Throughput, and a compact footprint rebalance the ledger. The Krell name carries the same kind of assurance for serious sonic performance that Hasselblad or Porsche carry in their fields. The unit measures 19 inches wide by 3½ inches high by 15½ inches deep (48.2 by 9.5 by 39.4 cm) and weighs 27 pounds (12.3 kg). Collectors chasing one today should expect the usual caveats for a late-1990s Krell: the tuner is the weak link and the damping factor is low by modern standards.
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