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This is something we don't see too often: an entirely new approach to power amplifier design. As Quad points out in its literature for the 405, class-A operation of transistors provides the lowest distortion, but drastically limits the amount of power an output transistor can deliver without overheating. (Most transistor amps use class-AB output operation, in which each of a pair of power transistors handles part of each signal cycle and shuts down during the other part. Imperfect synchronism between the two halves causes the familiar "crossover distortion," which accounts for most solid-…
J. Gordon Holt reviewed the Mk.2 version of the 405 in April 1983 (Vol.6 No.4):
Warning to purists: Despite certain qualities about Quad's ESL-63 loudspeakers that you will probably like, Quad equipment is not designed primarily for audiophiles, but for serious-music (call that "classical") listeners who play records more for musical enjoyment than for the sound. Quad's loudspeakers do not reproduce very deep bass and will not play at aurally traumatizing volume levels, and Quad's preamplifier is compromised through the addition of tone controls and filters, all for the purpose of making…
Sam Tellig wrote about the 405-2 in April 1985 (Vol.8 No.4):
"You bought Quads again!"
Now my son really thought the old man was nuts. In my last installment, I told you how I sold my Quad ESL-63 speakers. A little later, I sold my Quad 34 preamplifier and 405-2 power amplifier. Unlike the speakers, however, the 34 preamp and 405-2 power amp were two pieces of equipment I wished I hadn't sold.
Once again, I find myself at odds with other audiophiles (footnote 1). The prevailing wisdom seems to be that the Quad ESL-63 speakers are super (indeed, they are very good) while…
Sidebar: Specifications
Specifications: Two-channel, "current-dumping" solid-state power amplifier. Rated output: 100Wpc into 8 ohms (20dBW). Frequency response: -1dB at 20Hz (12dB/octave subsonic filter), -0.5dB at 20kHz, -3dB at 50kHz. Sensitivity: 500mV in for 100W out. Power bandwidth: 10Hz-20kHz. Damping factor: 80. Channel Separation: 85dB at 1kHz.
Dimensions: 13.4" (340mm) W by 4.5" (115mm) H by 7.7" (195mm) D. Weight: 20 lbs (9kg).
Price: No longer available; $410 (1976), $650 (1985).Manufacturer: Acoustical Manufacturing Co. Ltd. (1976); Quad Electroacoustics (1985); Quad…
Does the modern audiophile want a sleek, compact, powerful, remote-controlled, microprocessor-driven, two-channel integrated amplifier? Perreaux Industries, based in New Zealand, thinks so. They've designed all that, plus good looks and impressive build quality, into the R200i. Despite its relatively small size—4.1" tall by 16.9" wide by 13.4" deep—the R200i packs a punch. It's rated at 200Wpc into 8 ohms and 360Wpc into 4 ohms, yet it weighs just a fraction under 30 lbs.
In addition to power, the dual-mono R200i is packed with performance and convenience features. The…
Unlike with the Chord CPM 3300 integrated amplifier I reviewed in the July 2001 issue, setting up and customizing the R200i was neither confusing nor overly complicated. Rather than go through the entire process, I'll just tell you some of what you can do via the System Setup menu to alter the factory default settings. You can label each input with one of 25 choices (Phono, Tuner, CD, SACD, Computer, etc.) and set a default channel balance, initial and maximum volume (convenient when leaving the babysitter in charge of your stereo), display-screen brightness, and Time Out (which darkens the…
A few days after I started running the R200i in direct mode, Chad Kassem's (of Analogue Productions) personal vinyl test pressing of Dark Side of the Moon arrived. The commercial LP will be pressed in the Netherlands; Chad's was pressed at RTI. It was easy enough to switch the R200i back to integrated operation, audition the disc, then listen again in direct mode, running the Manley Steelhead phono preamp via its variable output. Even through the R200i's preamp stage, the Gray/Hoffman/Sax analog mastered Dark Side smoked the SACD in terms of richness, midband bloom, and sheer palpability.…
Sidebar 1: Specifications
Description: Remote-control integrated amplifier with MOSEFT output stage. Output power: 200Wpc into 8 ohms (23dBW), 360Wpc into 4 ohms (22.6dBW). Frequency response: 5Hz-100kHz, ±0.25dB (preamplifier); 5Hz-30kHz, ±0.5dB (power amplifier). THD: typically 0.0003% at 1kHz into 8 ohms, 0.0004% at 1kHz into 4 ohms. Voltage gain (preamp): 30dB. S/N Ratio (preamp): >95dB. Input impedance: 10k ohms. Input sensitivity: 205mV. Channel separation (preamp): 70dB at 1kHz unbalanced, 90dB at 1kHz balanced. Channel separation (power amp): 120dB. Damping factor: >2000.…
Sidebar 2: Associated Equipment
Analog sources: Simon Yorke S7, V.Y.G.E.R. Atlantis turntables; Immedia RPM-2, Graham 2.2 tonearms; Lyra Titan, Audio Tekne MC-6310, Transfiguration Temper W cartridges.
Digital source: Musical Fidelity Nu-Vista 3D CD player; dCS Elgar Plus/Verdi/Purcell SACD and CD-to-DSD playback system; Alesis Masterlink digital disk recorder.
Preamplification: Hovland HP-100 preamp, Manley Steelhead phono preamp.
Power amplifier: Musical Fidelity Nu-Vista 300.
Loudspeakers: Audio Physic Avanti III.
Cables: Phono: Hovland Music Groove, Graham IC-70.…
Sidebar 3: Measurements
My usual practice when measuring an amplifier is to precondition the device by running it with both channels driven at one-third power into 8 ohms for an hour. Though these conditions are unlikely to be met in real life (other than in the well-known "Party Test"), they maximize the thermal stress on the amplifier if it uses, as do 99.99% of amplifiers brought to market, an output stage biased to run in class-B or -A/B.
The Perreaux R200i's heatsinks got hot very quickly at this power level; the integral heatsink-temperature display showed that, from an…