Marantz SM-11S1 Reference power amplifier
While their individual histories, and how each managed to survive more or less intact for all these years, couldn't be more different, today both McIntosh and Marantz are parts of D&M Holdings, a Japanese corporation that also owns Denon, Boston Acoustics, and Snell, among other familiar brands.
But rather than exploit, degrade, and commoditize these venerable names (can you believe that the guy who bought Polaroid stopped making instant film?), D&M Holdings seems to be encouraging these companies to devote their resources to core products and traditions while at the same time taking into account marketplace realities. Not all of the brands' previous owners were as forward thinking, which may explain why a full decade (1984–1994) passed during which Marantz offered no high-quality separate components, instead designing and selling only low- and mid-priced integrated amplifiers and receivers.
Marantz re-entered the High End in 1994, with the introduction of the SC-5 preamplifier and SM-5 power amplifier, both products part of the company's "Reference" line. Continual refinements and upgrades followed, and by 2006 the two models had morphed into the SC-7S2 Reference preamp ($7499.99) and the MA-9S2 Reference monoblock ($7499.99 each). The $22,500 needed to buy a preamp and a pair of amps put them out of the reach of all but a few audiophiles. To attract more customers, Marantz then introduced the PM-11S1 Reference ($3599.99), a high-quality integrated amplifier that included circuit elements from both separates, though neither its build quality nor its performance could compare.
The new SM-11S1 Reference amplifier ($3999.99) and matching SC-11S1 Reference preamplifier ($2999.99), Marantz's first midpriced separates in 24 years, offer an upgrade for audiophiles looking to graduate from more modest electronics without draining their bank accounts, and serve as sophisticated core components for newcomers with the money to comfortably spend upward of $20,000 on a complete first system.
Though the SM-11S1 and SC-11S1 use basic circuit technology derived from the SC-7S2 and MA9S2, both are entirely new products built to levels of inner and outer quality that make their relatively low prices all the more remarkable. Even adding a second SM-11S1 and running the pair as bridged monoblocks costs only half as much as the SC-7S2 and two MA-9S2s. Marantz's evident optimism about the midprice segment of the current two-channel marketplace should be shared by stereo enthusiasts.
Inside the copper-clad chassis
The SM-11S1, reminiscent in styling of Marantz's classic Model 9, is rated at 110Wpc into 8 ohms or 220Wpc into 4 ohms, 20Hz–20kHz, both with both channels driven.
Marantz claims that its symmetrical Parallel Line Layout, which you can see when you remove the thick, nonferrous aluminum cover, minimizes the current loop's path, and so improves the circuit's ability to reject external noise and limits the amount of noise it generates itself.
A large, 14.5-lb toroidal transformer is encased in an aluminum enclosure and bolted to the chassis through a 10mm-thick aluminum base plate. The transformer has a double core of silicon-steel sheet; acoustic-isolation plates and spacers between the primary and secondary coils are claimed to improve its rejection of high-frequency noise.
The transformer's bifilar-wound (parallel) coils, permit separate rectification of the left and right, positive and negative voltage rails. That and other power-supply innovations are claimed by Marantz to eliminate capacitive coupling, and produce degrees of channel separation and ambience retrieval comparable to those of separate monoblocks. The power supply's two custom-designed 15,000µF filter caps per channel are similar to those used in the MA-9S2 and were chosen for their sound quality.
High-quality components, including high-speed Schottky diodes and the same Blue Star caps used in the SC-7S2 and MA-9S2, are used throughout the SM-11S1, which also uses no fewer than 34 compact HDAM SA3 ultra-high-speed amplifier modules. The SA3, the latest iteration of Marantz's High Definition Amplifier Module (HDAM) complementary cascade push-pull circuit, is a compact arrangement containing high-precision, surface-mount metal-film resistors said to be stable and to remain within spec throughout a wide range of temperatures.
The SM-11S1 uses two stages of output amplification: a 13dB voltage amplifier, and a 10dB power-buffer amplifier capable of providing sufficient instantaneous high-current drive to counteract back EMF from the drive-unit and thus better control the speaker cones' excursions. The first stage of this two-stage amplifier is a fully balanced, current-feedback voltage amplifier that lowers the signal impedance and is identical to the one used in the more expensive MA-9S2. HDAM SA3 modules handle the differential input, with each input independently buffered. The second stage, a current-feedback power-buffer amp incorporating the aforesaid complementary cascade push-pull circuit, drives the speakers directly.
Is it important that you know this stuff? Perhaps not, but surely many readers understand the terms push-pull, complementary, and cascade, though the SM-11S1's incorporation of "Wilson current mirror" and "cascade bootstrap" circuits probably does push the knowledge envelope. The important thing to know about these buzz words is that they are claimed to improve the SM-11S1's ultra-high-frequency performance while lowering distortion, which should be important in the reproduction of music from SACD and DVD-Audio discs.
Among the SM-11S1's modern conveniences are balanced and unbalanced inputs, each with independent gain setting, –6dB , 0dB, or +6dB. This allows you to use the amp, for example, with both the SC-11S1 preamp in balanced mode, and with an A/V receiver via the latter's front L/R channel unbalanced preamp output. The balanced-mode input can be set to 0dB, while the gain of the unbalanced input can be set higher or lower to better match it with other channels driven by the receiver.
The SM-11S1's digital power meter lets you monitor power output in two modes: updated once per second, or only when the highest-registering output is surpassed. The meter operates independently of the output to the speakers, via a Hall sensor that detects the current output magnetically, with no effect on sound quality.
The SM-11S1's rear panel includes a trigger input jack that permits remote power control when linked with the SC-11S1 or other trigger-operated Marantz electronics. Switchable dual sets of WBT speaker terminals (of the vile, EU-compliant, plastic-sheathed ilk) can be used for biwiring, or for connection to two pairs of speakers. There is also a bridging switch and a ground-lifted IEC jack.
On the sculpted front panel, six small pushbuttons, each illuminated with a blue LED, are tucked into creases to either side of the raised central faceplate, which contains the illuminated power meter and a large On/Off button. The three buttons on the left control the Display illumination and choice of speaker outputs, the three on the right the meter mode and balanced or unbalanced input.
Sound: fast, clean, exciting
You'd think that replacing my accurately named kW monoblocks from Musical Fidelity with a puny stereo amp rated at only 110Wpc would produce an across-the-board sonic letdown. That's what I expected, too, even considering the Marantz SM-11S1's claimed output of 200Wpc into 4 ohms, which happens to be the nominal impedance rating of my Wilson Audio Specialties MAXX 2 loudspeakers.