Mark Levinson No.334 power amplifier Page 2

Space doesn't allow a full description of the design features shared by the Nos.331 and 334; for that, consult the original review in Vol.19 No.1. Briefly, the dual-mono configuration features large independent power supplies with two 801VA toroidal transformers, one for each channel, oriented to cancel stray magnetic fields; and balanced circuit technology derived from the No.33 and No.33H reference monoblocks. The circuitry includes two triple-bypassed, 44,000µF, low-ESR electrolytic filter capacitors per channel; a soft-clipping circuit to reduce the audible effects of amplifier clipping or overload; adaptively biased output stages that are intended to provide much of the benefits of class-A operation without generating huge amounts of heat; and independent regulation of all voltage gain-stages.

The No.334 includes the exotic "S"-series printed circuit board material—a cyanate-ester composite—used in Madrigal's Reference No.33 and No.33H amplifiers. These PCBs have a lower and more stable dielectric constant, resulting in better electrical isolation of circuit stages and improved sound. Madrigal's David Nauber explained that if the dielectric constant is too high—as it is with fiberglass—the PCB signal traces, separated by dielectric configuration, can store energy like a capacitor and cause the circuit board "to sing along with the music." The two avocado-green cyanate-ester voltage-gain (VG) PCBs that lie just under the 334's top cover cost Madrigal 10 times more than the No.331's original dark-green fiberglass VG boards. Because Madrigal attributes much of the No.334's sonic improvements to the new boards, they are available as a dealer-installed upgrade kit to No.331-333 owners for $1950 (see sidebar).

I began listening the day the first No.334, a pre-production model (serial no.1194), arrived. Two weeks later, Madrigal shipped me a full production model (serial no.1252) that differed only in the addition of two diodes to its soft-clipping circuit. Because one can never have too many amplifiers, I expanded my listening tests to include both amplifiers, used in bridged or biamped mode.

Setting up most two-channel stereo amplifiers doesn't require reading a manual. Not so with the No.334. If you don't read p.6 of the 38-page manual—and you should before unpacking this amplifier—you won't know that Madrigal strongly advises a minimum of two people remove it from its shipping carton. The manual warns that the No.334 should be "handled with extreme care to avoid injury." I completely agree—this dense, sharp-finned, handleless, 108-lb mass of steel proved very tricky to steer behind speakers without lots of planning. That's why two pairs of white knit gloves—for two unpackers—are shipped with each new 300-series amplifier. These gloves bear the Madrigal insignia on the back, and have a rough, nubbled-rubber palm surface that gives them terrific gripping power while protecting hands from being cut by the heatsinks.

Turning on the amplifier properly also requires a study of the manual, which explains on p.15 that the No.334 needs a minimum of 10 seconds—about four cycles of the slowly blinking front-panel indicator light—before its power supply is fully charged and its circuits are stabilized. The No.334 ignores those who repeatedly push its front-panel standby button—like my 21-year-old son, who tried to play his didgeridoo album while I was at work (footnote 2). Turning off the amp by its rear-panel AC mains switch instead of using the standby button generated a spray of static in the speaker from the pre-production No.334, but not in the production model.

The 100A-rated, insulated loudspeaker terminals didn't accept my Qudos QED speaker cables, which terminate in banana plugs (footnote 3). As a result, I had to use spade-lug-tipped PSC Pristine R50 biwired speaker cables. The amplifier was driven in single-ended mode from a Mark Levinson ML-7A preamplifier using Levinson interconnects via RCA inputs, and in balanced mode from a Krell KBL preamplifier using balanced PSC Pristine R30 Silver Alloy interconnects via XLR inputs.

The good news is that the No.334 played with clarity, liquid mids and highs, stunning transparency, and an ability to render dynamic contrasts not evident in listening to the No.331. Whether driving the Dynaudio Contour 3.0, Quad ESL-63, B&W 805 Nautilus, or Revel Salon speakers, both Mark Levinson No.334s did a superb job—I heard no differences between the pilot and production units. The No.334 was ultra-clear, transparent, and in complete control. Midbass, midrange, and highs were very, very smooth. Slightly brighter with the Quads than comparison amplifiers, the No.334 was second to none in infusing them with dynamic impact, transparency, and low-frequency solidity.

The biggest improvement the No.334 wrought in dynamic loudspeaker systems was in bass impact. Up till then, along with the discontinued Krell KSA-250, the Bryston 4B-ST stereo amplifier had been my bassmaster, coaxing slam and bass heft from just about any dynamic loudspeaker. All of a sudden, I knew there was a new kid on the block. Powered by the No.334, even the diminutive B&W 805 Nautilus two-way bookshelf speaker tracked the deepest synthesizer notes, producing powerful, subterranean bass from I Ching's "Silk Road," from Of the Marsh and the Moon (Chesky WO144).

Its bass slam and definition enabled the No.334 to convey jaw-dropping dynamic contrasts. This effect was much more than just extra headroom. Through the Revel Salons, the No.334 resolved what seemed to be the most subtle dynamic differences, whether the speakers were driven to lease-breaking levels or played softly. When I listened to "The Hand-Off," from the Sneakers soundtrack CD (Columbia CK 53146), explosive piano scales jumped out of dead-black silence to send chills up my spine.

Footnote 2: According to the manual: Switch on rear-panel AC mains; push the front-panel Standby button to bring the amplifier from Off to Standby; wait 10 seconds as the indicator light slowly flashes; then push the Standby button a second time. If this procedure has been followed, the internal relays will make a number of soft cricket clicks, after which music can be played.

Footnote 3: "CE-certified" products are designed so that speaker terminals will not accept dual banana plugs. The AC mains cables some European countries use resemble dual bananas, which means that they can be accidentally—and disastrously—plugged into amplifier speaker terminals.