search
A large toroidal transformer behind the front panel supplies power to three stacked printed-circuit boards behind the transformer. The bottom two boards carry multiple storage capacitors, the top board the relay and housekeeping circuitry. All the audio circuitry, including the 36 output devices, is carried on two six-layer boards mounted either side of the fan tunnel. This allows signal paths to be very short, minimizing any parasitic effects and keeping the amplifier's noise floor very low. The circuit is new rather than developed from earlier Classé designs. Both balanced and unbalanced…
Sidebar 1: Specifications
Description: Solid-state, fan-cooled monoblock power amplifiers. Rated output: 600W into 8 ohms (27.8dBW), 1200W into 4 ohms (27.8dBW). Peak output voltage: 226V p–p, 80V RMS no load; 206V p–p, 73V RMS into 8 ohms. Frequency response, CT-M600: 1Hz–80kHz, +0/–3dB. Frequency response, CA-M600: 1Hz–100kHz, +0/–3dB. Voltage gain: 29dB into 8 ohms, balanced and unbalanced. Input sensitivity: 2.86V for full power. Input impedance: 50k ohms balanced and unbalanced. Output impedance: 0.03 ohm at 1kHz. Harmonic distortion: <0.002% at 1kHz, balanced; <0.004% at 1kHz…
Sidebar 2: Associated Equipment
Digital Sources: Ayre Acoustics C-5xeMP universal player; dCS Puccini SACD player with U-Clock; Apple G4 Mac mini running OS10.5.8, iTunes 10, Pure Music 1.6; Shuttle PC with Lynx AES16 and dual-core AMD Athlon processor running Windows 7, Foobar 2000, Adobe Audition 3.0; dCS Debussy, Esoteric D-07, Benchmark DAC1, Logitech Transporter D/A converters; Halide S/PDIF Bridge USB-S/PDIF converter.
Preamplifier: Simaudio Moon Evolution P-8.
Power Amplifiers: Parasound Halo JC 1 monoblocks, Simaudio Moon Evolution W-7, NAD M2.
Loudspeakers: Harbeth…
Sidebar 3: Measurements
I carried out a complete set of tests on the Classé CT-M600, repeating some of the tests on the CA-M600. (The CA-M600 basically performed identically, other than a very slightly wider small-signal bandwidth.) To perform the measurements, I used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and www.ap.com). Before doing the testing, I ran the Classé CT-M600 at one-third its rated power for 60 minutes, which thermally is the worst case for an amplifier with a class-A/B output stage. At the end of…
The latest two offerings from Music Matters Jazz—Lee Morgan's Indeed! and Jackie McLean's Destination Out!—are the company's best in a while: most worthy of the exclamation points.
MMJ, of course, is the jazz-loving audiophile-house that reissues classic Blue Note albums, spread out on two slabs of 180gm vinyl, mastered at 45rpm, and tucked inside gatefold packages featuring high-rez studio photos on the inside and pristine reproductions of the original covers on the outside.
Indeed! was Morgan's debut, recorded in 1956, when the trumpeter was a mere 18 and already wowing Dizzy…
Boston Acoustics A Series loudspeakers—on the beach, which is where I'd like to be right now.
Is it just me or are we really experiencing the beginnings of a new stereo renaissance, a return to dedicated, high-quality, two-channel sound? Could it be that the home theater sector has become almost entirely commoditized so that little besides cost and availability are important to the consumer? In an age when craftsmanship and dedication have become clouded by convenience and fashion, hi-fi—good, old-fashioned, two-channel hi-fi—symbolizes the importance of quality…
In my review of Krell's FBI integrated amplifier in the July 2007 issue, I noted that $16,500 (it now costs $18,000) seemed an astonishing chunk of change to spend on a product category generally associated with "budget" gear. Now, the 2011 edition of the Stereophile Buyer's Guide lists no fewer than 19 companies selling integrated amps for five figures—one goes for $100,000!—which perhaps suggests that economic slumps prod even the well-heeled to alter their habits. There are, after all, advantages to cramming a preamplifier and a power amplifier into a single box: you need one less pair…
The bottom line: The Krell has a slight edge in deep bass, dynamics, and capturing the forward edge of transients—the initial whack of a drum, the pluck of a string, the sss of a sibilant—while the Moon had a slight edge in getting the tonal colors of an instrument or ensemble, the flow of a rhythm, and a seamlessness across the audioband, from bass to midrange to airiest highs. A crude and perhaps overdramatic way of summarizing it: The Krell is a bit more lively, the Moon a bit more lifelike.
Notice my qualifiers: "a slight edge" in this or that, "a bit more" lively or lifelike. The…
Sidebar 1: Specifications
Description: Two-channel, solid-state integrated amplifier. Inputs: 1 pair balanced (XLR), 5 pairs single-ended (RCA). Speaker outputs: 2 on gold-plated binding posts. Preamp output: 1 pair single-ended (RCA). Preamplifier section: Frequency response: 10Hz–100kHz, ±3dB. Signal/noise ratio: 120dB, 20Hz–20kHz. Power amplifier section: Maximum output power: 175Wpc into 8 ohms (22.43dBW), 300Wpc into 4 ohms (22.43dBW). Maximum output voltage: 45V. Gain: 37dB. Signal/noise: 105dB at full power. THD: <0.015% at 1W, <0.04% at 150W, 20Hz–20kHz. Damping factor:…
Sidebar 2: Associated Equipment
Analog Source: VPI Classic turntable with VPI JMW Memorial tonearm, Lyra Delos cartridge.
Digital Source: Krell Evolution 505 SACD/CD player.
Phono Preamplifier: Nagra BPS (battery-powered).
Integrated Amplifier: Krell FBI.
Loudspeakers: Revel Ultima Studio2.
Cables: Interconnect: Nirvana, Krell CAST (with Krell FBI). Speaker: Nirvana.
Accessories: Bybee Technologies Signature Power Purifier (except for amps), Black Diamond Mk.4 Racing Cones, VPI HW-19 record-cleaning machine.—Fred Kaplan