再贴一篇《steorophile》的评论
Mark Levinson No.383 integrated amplifier
Larry Greenhill, July, 2000
When I learned that Madrigal Audio Labs was marketing their first integrated amplifier, the Mark Levinson No.383, I felt this was a big change for the Connecticut company. Mark Levinson literally started the high-end marketing revolution back in the early 1970s by manufacturing cost-no-object separate amplifiers and preamplifiers. The purist designs had one overriding rule: employ the simplest circuit path possible. Each amplifier or preamplifier used only individual circuit-board components (no integrated circuits) and had a minimal number of controls, eschewing elaborate switches and tone controls. Mark Levinson Audio Systems and its successor, Madrigal Audio Laboratories, has continued this philosophy of separate components for the past 25 years.
But the integrated amplifier—preamplifier and two-channel amplifier built on the same chassis—has recently become a hot item in the High End.
Just read Sam Tellig, who's been turning in raves about integrateds: the Bel Canto SETi40 (Vol.22 No.3), the Bryston B-60 (Vol.20 No.5), the Conrad-Johnson CAV-50 (Vol.21 No.8), the Jadis Orchestra (Vol.20 No.1), the Pathos Acoustics Twin Towers (Vol.22 No.1), and the YBA Integré DR (Vol.19 No.12).
Chip Stern, the magazine's eminent jazz expert and all-around music-lover, has been doing his own integrated thing, praising the EAR V20 (Vol.22 No.10), the Manley Stingray (Vol.22 No.12), the Mesa Tigris (Vol.22 No.8), and the VAC Avatar (Vol.23 No.4). As a result, the "Integrated Amplifiers" section of Stereophile's "Recommended Components" (RC) listings has swollen to six Class A and 11 Class B amplifiers.
Why have two-channel integrated amplifiers taken the High End by storm, when the rest of the massmarket industry is obsessed with 5.1-channel A/V receivers? Three little words say it all: price, price, and price. The Class A integrateds in RC are priced from $2395 to $5200, just a fraction of the cost of a comparable combo of separate, top-quality power amplifier, preamplifier, and interconnects.
Why is the integrated more economical? It's less expensive to build, having just one chassis and shipping carton compared with up to four of each for high-end separates, such as the combination of a Mark Levinson No.32 preamplifier (control chassis and preamplifier chassis) and two No.33H monoblocks. Each chassis and its carton add greatly to the cost. Current integrated designs get rid of internal phono stages and achieve further savings with a closed design that doesn't interface with other amplifiers or preamplifiers. This eliminates the circuits for a preamplifier output buffer and power-amp input buffer.
There are other savings. Packing a stereo preamplifier and two amplifier channels into one chassis saves space. Hum is reduced because amplifier and preamplifier now share exactly the same ground voltage, so less shielding is required. And an integrated weighs less—when did you last own a basic amplifier that fit on a shelf, or, for that matter, could even be lifted by one person? No more tripping over massive, sharp-finned amplifiers in the dark. Equipment clutter goes down, and the spouse acceptance factor goes up. This "sweet spot" of compact size and affordability keeps the integrated alive.
All this contributed to my surprise and glee when I first read about the No.383. I wasn't alone. Jon Herron, manager of product development at Madrigal, was beaming (I could tell, even over the telephone) about the new No.383's economics, ergonomics, build quality, and user-friendliness. "Sonically, it's as close as we could make it to the performance of a No.334 driven by a No.380 preamplifier," he said. "And if you fail to use the best interconnect, a No.383 will be better. Its repeatable gain settings and user-friendliness also make it an excellent reviewer's tool." User-friendly and a better reviewer's tool? I couldn't wait.
Ergonomic Heaven
That user-friendliness begins with the No.383's size and weight. At 65 lbs, this baby is the lightest and smallest ML amplifier. The 112-lb No.334 ($5900), the 155-lb, 250Wpc No.335 ($7900), and the 165-lb, 350Wpc No.336 ($9500) are so massive that they require two people—both wearing Madrigal's white-ribbed protective gloves, of course—to safely unpack them.
Stacking the No.383 atop a Mark Levinson No.334 made this point convincingly. The No.383 shares most of the No.334's physical dimensions, including its width and depth. It, too, has the rounded heatsink edges and curved silver faceplate trim, as well as the Mark Levinson massiveness and silver-accented art deco curves. Only the No.383's height—less than half the No.334's—suggests that it's the "entry-level" Levinson amp.
Even so, its front panel is a dead ringer for the No.32 Reference stereo preamplifier ($14,000), which so impressed Jonathan Scull (Vol.22 No.1). An AC mains switch sits to the right of the red alphanumeric display, and a standby switch to the left. When in standby, all circuits up to the output stage remain powered, decreasing warmup time and extending average component life. Two large rotary controls—for setting the volume and performing input selection—frame the display. Below the display is a row of pushbuttons for Display intensity, Setup, Enter (for saving setup changes), Balance, and Mute.
But these switches aren't the main user interface. The No.383 is best controlled by its classy remote, ergonomically sculpted from aluminum. This soapbar-shaped device switches the No.383 in and out of Standby mode and adjusts balance, volume, display intensity, polarity, source, and mute. For the first time, from 12' away in my listening chair, I had complete command over source selection, system volume, channel balance, polarity, and mute.
Installation involves running the No.383's setup routine. Like the top-of-the-line No.32, the integrated amplifier is built around a software-based operating system that can be upgraded by loading the update through its RS-232 port. In fact, it's the same operating system as runs the No.32. Stepping through the menus on the front-panel display designates each source plugged into a back-panel input, assigns it a display name, and sets the gain level. Optimum performance settings for each source can be adjusted, titled for the display, and saved. Each line-level input can be customized by name (26 name options included, plus 7-character user-defined names), gain (0dB, +6dB, +12dB, or +18dB), offset (relative gain adjustments of ±20dB in 0.1dB increments), and record output. Only active inputs are included, so that the choices include only those line sources actually plugged into the back of the No.383. Once named on the alphanumeric display, the source can be selected from the remote, which can then control its gain, polarity, and mono/stereo settings. And the Mute mode's drop in volume level can be set anywhere from -10dB to -70dB in 0.1dB increments.
From the start, I liked the No.383's sophisticated operational features. Besides increasing or decreasing the gain from 0dB to +72dB in 0.1dB steps, the control adjusts the rate of volume change, according to the starting gain level and the rate of change in level. Turning the control quickly by hand accelerates the volume change, yet if the knob is spun too quickly, the rate of change decreases, to keep from jacking up the volume too rapidly.
These elements—the operating system's many custom features, individual 0.1dB control over gain, balance, and input offset, full remote control, the ability to work with learning remotes, and the "smart" volume control—make the No.383's user interface a real breakthrough in ease of use, flexibility, and control.
Circuitry and Construction
The No.383's back panel features five analog input pairs, for use with sources single-ended (three pairs of Madrigal-designed RCA inputs) or balanced (two pairs of Swiss-made XLR inputs). The No.383's rear handles protect the interconnect cables if the unit is upended onto its rear panel. All the sockets mount directly to the printed-circuit board (PCB), and inputs are independently buffered. Unselected inputs have their ground connections lifted, eliminating a path by which noise might enter the chassis. All single-ended signals are converted to balanced at the input and remain balanced up to the final current stage. A separately buffered, single-ended record output monitors the selected source. This fixed-level output can be switched off.
Four types of control ports give the No.383 many options. There is one 3.5mm mini-jack for an external infrared receiver module if the unit is placed in a cabinet. DC trigger voltage in and out are handled by separate 3.5mm mini-jacks. The 6-pin RJ-11 RS-232 port allows the operating system's software to be updated, and can also be used for external control by a master control system such as an AMX or Crestron. The No.383 supports communications via two 8-pin RJ-45 PHAST-compatible Mark Levinson Link communications ports for two-way communication with a home automation system. This is offered for future integration with PHAST-controlled systems by installing an optional PHAST control board.
Three power supplies dominate the No.383's circuit board. All communication and control circuits are powered from a separate, low-voltage DC supply with its own transformer—a small, gray block in the front of the chassis. DC regulators are used to provide stable power and to prevent noise generated by the control and communications circuits from finding its way into the audio circuits.
The second and third power supplies are actually two independent DC supplies devoted to the left- and right-channel audio circuits. This duplication ensures that demand from one channel does not modulate the other's power supply. Two large, custom-designed toroidal transformers reduce the AC mains voltage to the ±60V rails. Independent rectification and filtering are followed by active regulation for the voltage-gain and volume-control circuits. High-frequency AC line noise is filtered by common-mode and differential filtering capacitors. Metal-oxide varistors are used for surge and spike protection on the AC line, and prevent excessive inrush current from damaging expensive power-supply components at power-on.
The preamplifier section begins with the gain control. Solid-state stepped attenuators offer precision control of balanced analog signal volume. Local supply regulation and passive bypass components are fine-tuned during the design compensation process to optimize the No.383's sonics during listening tests. Overall gain for the preamplifier section can be adjusted to optimize the volume-control range for loudspeakers of differing voltage sensitivity. Unity gain occurs when the display reads 67dB.
The No.383's amplifier section employs the same output-stage devices (12 per channel) as are found in Mark Levinson's 300-series dual-mono amplifiers. These bipolar power transistors are packaged in small plastic cases—rather than in the more microphonic-prone metal TO3 cans—and are clamped to the heatsinks with an aluminum bar. The end result is an output stage with low noise, low THD and IMD, and excellent squarewave performance. This stage runs at relatively low temperatures due to the wide spacing of output transistors along the current-gain circuit board and the custom heatsink extrusions mounted on the side of the chassis. Even with its compact chassis, the No.383 delivers 100Wpc at 8 ohms and 200Wpc at 4 ohms continuous, both channels driven, 20Hz-20kHz.
Extensive protection from internal and external component failures is provided. Fuses and a mains relay, driven by AC line voltage and frequency-sniffing sensing circuitry, protect the unit from under- and over-voltage conditions. Four sensors mounted on each rail of the left- and right-channel output stages provide thermal protection. Other switches, located inside each transformer housing, disconnect power if the transformer overheats. Soft-clip circuits are used to prevent high-energy, high-frequency ringing artifacts from reaching and damaging loudspeakers. Overdriving the amplifier for long periods or shorting its output switches it off.
Even with these features, Madrigal's engineers kept the No.383's costs down. As the preamp and power-amp sections don't have to deal with unknown situations, the respective output and input buffers can be eliminated. There is no headphone plug on the front panel, as is sometimes found in other integrated amplifiers. Rather than using exotic materials for the PCB, such as the No.334's avocado-colored cyanate-ester voltage-gain boards, the No.383 uses grade 10 FR-4 glass epoxy PCBs at one eighth the cost.
Madrigal designed the '383 to be operated only into 8 and 4 ohm loads, not for costly continuous 2 ohm capability. There is no separate Record/Monitor path, and no phono stage. These would have added considerable cost in shielding and advanced low-level circuitry. There is only one pair of propeller-wing speaker binding posts per channel, rather than the dual pairs found on all Mark Levinson power amplifiers. The circuit uses standard components, not cost-no-object Vishay resistors and WonderCaps. This isn't necessarily a bad thing. For example, ML found that inserting a local bypass in the current-to-voltage-converter circuit led to bigger sonic benefits than did the use of an expensive resistor or capacitor.
Listening
Most listening was done in the nearfield of my current reference loudspeakers, the Revel Salons. These sat on a circular area rug, 63" from the rear wall and 36" from the sidewalls. Imaging and soundstaging were optimized when speakers and listening chair described an 8' equilateral triangle, measured from the tweeter centers.
The good news is that the No.383 played with clarity, transparency, liquid mids and highs, and an ability to render dynamic contrasts second only to that of the Mark Levinson No.334. Whether driving the Dynaudio Contour 3.0s, Quad ESL-63s, B&W 805 Nautiluses, Dynaudio Evidences, or Revel Salons, the No.383 sounded powerful, fast, smooth, articulate, and dynamic—clear and in complete control. The midbass and midrange were smooth and grain-free. Driving the huge Evidences that I reviewed in May, their sound was fast, detailed, and smooth, with extended highs.
The No.383 delivered solid, dynamic sound without being edgy or analytic, and with a bass response that was both controlled and detailed. The bass notes in Massive Attack's Unfinished Symphony (Circa WBRX2) were driving, taut, solid, and punchy. The soundtrack from My Cousin Vinny (Varese Sarabande VSD 5364) had slam, punch, and drive. Deep synthesizer notes, such as the entrance of the ghosts in the Casper soundtrack (MCA-11240), were solid and ultra-deep with great pitch definition, all set against a deep, wide soundstage. The substantial weight of the distant bass synthesizer on "Silk Road," from I Ching's Of the Marsh and the Moon (Chesky WO144), was offset by the song's soft, rainy acoustic landscape.
Then there were the deep, defined bass notes I heard on Patricia Barber's Companion (Premonition/Blue Note 5 22963 2), recorded live at the Green Mill in Chicago. The stand-up bass on "Use Me" vibrated all my cabinets. "Like LJ," the album's instrumental, was stunning in bass drive and tautness, and the pitch definition of Michael Annope's string bass, Ruben Alvarez's bongos, and Eric Montzka's drums. My notes: "This bass swept me away..."
Big-band drumming was as good as it gets. The No.383 put me in the catbird seat when I listened to Buddy Rich wail on his drum kit during his 1961 recording of "West Side Story Medley" (on Swinging New Big Band, Pacific Jazz CDP 8 35232 2). Backed by Jim Trimble's hot, brassy trombone solo and the front line of Bobby Shaw, Sohn Sottile, and Yoshito Mohrakami, Rich's kick drum races ahead, propelled at a much, much faster tempo than contemporary solos.
Vocal and jazz recordings were precise, defined, and smooth. Harry Connick, Jr.'s voice on "I Don't Get Around Much Anymore" (from the When Harry Met Sally... soundtrack, Columbia CK 45319) was smooth and pure without sounding tubby or nasal. The stunning, realistic rimshot that closes this song has to be heard to be believed. Whether it was Marc Anthony's clear, pure tenor blending with Ruben Blades' baritone in "Time is an Ocean" (from Songs from The Capeman, Warner Bros. 46814-2), the blending of Emmylou Harris' and Buddy Miller's voices in "The Maker" (from Spyboy, Eminent EM-25001-2) as they sing the words "Cold river rise from your sea," the distinctness of each singer's voice, contrasted with the other, made for a highly realistic and involving listening experience.
The No.383's extended, transparent upper register allowed me to hear both the cymbal sheen on Wynton Marsalis' "The Resolution of Romance" (Marsalis Standard Time, Vol.3, Columbia CK 46143) and the shimmering sound of the opening cymbal work from "The Mooche" (Rendezvous: Jerome Harris Quintet Plays Jazz, Stereophile STPH013-2). Piedmont blues guitarist Etta Baker's "I Get the Blues When It Rains" (Railroad Bill, Cello Music Maker 91006-2) transfixed me with the rich harmonies of the guitar's metallic strings. The No.383 helped the Revel Salons create a realistic illusion of a waterfall spilling into a pool when playing I Ching's "Running Water" (Of the Marsh and the Moon). The image—so three-dimensional and real—was typical of the No.383's detailed soundstaging.
Although I greatly enjoyed listening to the No.383, one thing was missing: more power. The integrated was perfectly capable of driving the Revel Salons, but not to disco levels. Only powerful separate amplifiers like the Bryston 7B-ST could re-create full-volume percussion in my large listening room without compression. To its credit, the No.383 smoothly limited rather than clipping audibly when I cranked up the volume during the opening timbale solo of "Tito," from Arturo Sandoval's Hothouse (N2K 10023). Tito Puente's explosive rimshots softened but did not choke or blur.
Conclusions
At $5990, the Mark Levinson No.383 is expensive. But if you're looking for a solid-state integrated amplifier that's well-built, flexible (six inputs, balanced and single-ended), and engineered to pay careful attention to the purity of the incoming line-level signal, the No.383 merits serious consideration, whether or not its cost is an issue. It's that good.
It's such a good value because it combines the user-friendliness and customizability of the Mark Levinson No.32's software interface with the ultra-rugged, over-designed dual-mono power amplifiers of the company's 300 series. Add the compact size, excellent sound, and a five-year warranty, and you have one very desirable product.
Madrigal's gamble of going against their traditional product image is likely to pay off. Be sure to get in on this sea-change: Audition the No.383 integrated amplifier.
Sidebar 1: Specifications
Description: Solid-state integrated stereo amplifier.
Preamplifier section: Line-level inputs: two pairs balanced (XLR), three pairs single-ended (RCA, optional). Outputs: one pair record outputs (RCA), one IEC AC mains receptacle, one ground terminal. Controller connections: three 3.5mm mini-jacks (IR input, DC trigger out/in), one Mark Levinson Link communications connector, one 6-pin RJ-11 RS-232 port, two 8-pin RJ-45 control ports (PHASTLink-compatible). Voltage gain: 0, 6, 12, or 18dB in line stage (26.9dB in amplifier stage). Volume control range: 72.2dB. Gain resolution: 0.1dB steps above 38.5 in display (-34.7dB). Input overload: 4V on XLR, 2V on RCA (gain set to +12dB); 16V on XLR, 8V on RCA (gain set to 0dB). Frequency response: 10Hz-40kHz, ±1.0dB. Input impedance: 100k ohms. THD+noise: ±0.3%. Mains voltage: 100V, 120V, 220V, 230V, or 240VAC at 50 or 60Hz (factory set). Power consumption: typically 100W at standby, 200W at idle, 1200W at 4 ohms at rated output.
Amplifier section: Rated output power: 20Hz-20kHz, less than 0.3% THD (FTC): 100Wpc into 8 ohms (20dBW), 200W minimum continuous into 4 ohms (20dBW). Frequency response: 20Hz-20kHz, ±0.1dB. Output impedance: ±0.05 ohms, 20Hz-20kHz. Damping factor: greater than 800, 20Hz-20kHz into 8 ohms. Speaker connections: one pair Madrigal-designed speaker binding posts.
Dimensions: 17.56" (446mm) W by 6.55" (166mm) H by 19.5" (495.3mm) D. Shipping weight: 80 lbs (36.6kg).
Serial number of unit reviewed: 1054.
Price: $5900. Approximate number of dealers: 75. Warranty: 5 years.
Manufacturer: Madrigal Audio Laboratories, 2081 South Main Street, Middletown, CT 06457. Tel: (860) 346-0896. Fax: (860) 346-1540. Web: www.madrigal.com.
Sidebar 2: Associated Equipment
Analog source: Linn Sondek LP12/Lingo turntable with Ittok tonearm, Spectral moving-coil cartridge.
Digital source: Sony MZ-R90 MiniDisc player, Krell MD-1 CD transport, Denon DVD-3700 DVD player, Adcom GDA-700 D/A processor.
Tuners: Day-Sequerra FM Reference Classic, Rotel RH-10, Magnum Dynalab MD-102 with 205 Sleuth RF amplifier.
Preamplification: Krell KBL, Mark Levinson ML-7A with L-2 phono section, Duntech MX-10 moving-coil preamplifier.
Power amplifiers: Mark Levinson No.334, Bryston 7B-ST monoblocks.
Loudspeakers: Dynaudio Contour 3.0, Dynaudio Evidence, Revel Salon, B&W 805 Nautilus, Quad ESL-63.
Cables: Interconnects: Bryston, Krell Cogelco Yellow, PSC Pristine R30 silver-alloy (all three balanced), Randall Research and Mark Levinson HFC (with Camac connectors) single-ended, 75 ohm Silver Starlight digital coax. Speaker: Mark Levinson HFC-10, PSC Pristine R-50 biwired double ribbons.—Larry Greenhill
Sidebar 3: Measurements
A one-hour preconditioning warmup at one-third full power exerts maximal thermal stress on an amplifier with a class-B output stage, and after that hour the No.383 was indeed warm to the touch—but not so hot that I couldn't keep my hand on its heatsink.
The amplifier didn't invert absolute polarity. (The XLR inputs appear to be wired with pin 2 hot.) The input impedance was 19k ohms balanced and 10k ohms unbalanced at 1kHz, both lower than the specified 100k ohms. The tape output source impedance was a low 50 ohms. With the line-stage gain set to "6dB," which was how LG had it set up, and the volume control to its maximum "73.2" setting, the overall voltage gain into 8 ohms was 33.6dB, suggesting a power-amplifier gain of 27.6dB. The power-amplifier output impedance was very low at approximately 0.055 ohms across most of the audioband, this rising to a still negligible 0.065 ohms at 20kHz.
Because of this very low source impedance, there was virtually no change in frequency response as the load varied (fig.1). The response was flat from 10Hz to 20kHz, with then a 1dB drop at 90kHz and a 3dB drop at 180kHz. As a result, the amplifier's reproduction of a small-signal 10kHz squarewave was virtually perfect (fig.2). Channel separation (fig.3) was superb, at better than 110dB below 500Hz. There was a smooth increase in crosstalk at higher frequencies due to capacitive coupling. Nevertheless, channel separation was still around an excellent 80dB at 20kHz.
Fig.1 Mark Levinson No.383, frequency response at 1W into 8 ohms, 2W into 4 ohms, and 2.83V into dummy loudspeaker load (5dB/vertical div.).
Fig.2 Mark Levinson No.383, small-signal 10kHz squarewave into 8 ohms.
Fig.3 Mark Levinson No.383, crosstalk (10dB/vertical div., L-R dashed).
Small-signal THD was very low over most of the audioband, rising slightly in the top audio octave and into lower impedances (fig.4). The actual harmonic content was buried in noise at reasonable power levels; fig.5 shows that it is fundamentally third harmonic. At high powers (fig.6), the third harmonic rose to a still low 0.05% (-66dB) and was joined by the fifth at 0.01% (-80dB). Intermodulation levels were also respectably low, even just below visible clipping into a 4 ohm load (fig.7).
Fig.4 Mark Levinson No.383, THD+noise (%) vs frequency at (from top to bottom at 4kHz): 4W into 2 ohms; 2.83V into simulated loudspeaker load; 2W into 4 ohms; and 1W into 8 ohms (right channel dashed).
Fig.5 Mark Levinson No.383, 1kHz waveform at 12.5W into 8 ohms (top), distortion and noise waveform with fundamental notched out (bottom, not to scale).
Fig.6 Mark Levinson No.383, spectrum of 50Hz sinewave, DC-1kHz, at 145W into 4 ohms (linear frequency scale).
Fig.7 Mark Levinson No.383, HF intermodulation spectrum, DC-22kHz, 19+20kHz at 120W into 4 ohms (linear frequency scale).
Fig.8 shows the continuous output power with both channels driven into 8 ohms and 4 ohms. (When I tried this test into 2 ohms, the No.383 muted and displayed the message "Amp Fault" on its front panel.) The Levinson comfortably exceeds its specification, giving 145W into 8 ohms (23.9dBW) and 230W into 4 ohms (20.6dBW), both at the standard 1% THD+noise definition of clipping.
Fig.8 Mark Levinson No.383, distortion (%) vs continuous output power into (from bottom to top at 2kHz) 8 ohms and 4 ohms.
Repeating this test with one channel driven using a low-duty-cycle 1kHz toneburst of 10 cycles on, 400 cycles off—this better approximates a music signal—revealed the No.383 to be a powerhouse (fig.9). No less than 182.6W were delivered into 8 ohms with this signal (black trace) at clipping (horizontal magenta line). The 4 ohm delivery was 356W (red trace), the 2 ohm delivery 665W (blue)! Only into the punishing 1 ohm load did the amplifier falter, its output at clipping dropping to 75W (green trace), with a significant rise in distortion below that power.
Fig.9 Mark Levinson No.383, distortion (%) vs 1kHz burst output power into 8 ohms (black trace), 4 ohms (red), 2 ohms (blue), and 1 ohm (green).
But Madrigal doesn't specify the No.383 for continuous output into loads lower than 4 ohms. If you want an amplifier to behave as a voltage source down to 1 ohm, you should consider buying one of their separate power amplifiers.—John Atkinson
