Arcam FMJ P49 power amplifier

I first met electronics engineer John Dawson in 1979, at a British audio show. The company he'd co-founded, A&R Cambridge, had just launched the A60, a slim, elegant-looking, 40Wpc integrated amplifier costing only £99 (then equivalent to $217).

By the time I reviewed the Mk.2 version, in the October 1984 issue of Hi-Fi News & Record Review, the A60's price had risen to £199 ($248), the company was now called Arcam, and more than 22,000 A60s had been sold, making it one of the best-selling amplifiers in England. While preparing that review I had visited Arcam's factory, near the English town of Ely, where Dawson had shown me filing cabinets containing a separate manufacturing report for each and every one of those A60s.

Arcam's designer John Dawson (center) with managing director Charlie Brennan (left) and Sound&Vision editor-in-chief Rob Sabin (right). Photo: John Atkinson

In the 30 years since, Arcam's products have endured as a mainstay of the affordable-audio market—its budget-priced Alpha and Solo models and its somewhat more expensive FMJ series have been very favorably reviewed in Stereophile—so it came as a surprise to learn from Dawson, on a November 2013 visit to the company's new Cambridge-area headquarters, that Arcam was about to introduce a relatively cost-no-object amplifier, to be built in North America: Following their 2012 acquisition by Montreal-based JAM Industries—primarily a manufacturer and distributor of pro-audio gear—Arcam's design and engineering remained in the UK, with production of the affordable product lines offshored to China, and with the intent to manufacture Arcam's higher-end products at a JAM-owned plant in New York State.

Those new products—the FMJ C49 preamplifier, FMJ A49 integrated amplifier, and FMJ P49 stereo power amplifier—made their US consumer debut at the 2014 Rocky Mountain Audio Fest, where Jason Victor Serinus enthused over the sound the P49 was producing with Canton 2.3 Reference loudspeakers: "as full-range as can be, completely under control, and nail-me-to-the-wall fabulous," he wrote.

I signed myself up to review the FMJ P49 amplifier, which costs $4999 and is specified to deliver 200Wpc into 8 ohms or 400W into 4 ohms.

The FMJ P49
The FMJ P49's plain-looking aluminum front panel, finished in dark gray, is almost featureless: On it are only a power button; one pushbutton each to activate the two pairs of speaker outputs; and, at the bottom, a discreet slot that runs almost the full width of the amp, to provide cooling air to the internal heatsinks. The acoustically damped steel case is also finished in dark gray, with vents in the top and bottom panels to aid cooling. As well as the two pairs of speaker terminals, the rear panel offers balanced (XLR) and unbalanced (RCA) inputs, with a slide switch to choose between them. There is also a pair of Preamplifier Output RCAs that mirror the input signal. Two other slide switches select voltage gain (25 or 31dB) and Stereo or Bridged-Mono operation.

The P49 can thus be used as: a conventional stereo amplifier, with one of the speaker outputs active; biwired, with both speaker outputs active; a biamped mono amplifier, with the stereo outputs independently feeding a speaker's high and low sections; or a high-power monoblock, with the two amplifier channels in series. The excellent manual gives full details on how to operate the P49 in each of these modes.

Plain on the outside, the P49 is elegant within. A large toroidal power transformer lies behind the left-hand side of the front panel, the heatsink next to it taking up the rest of the width. Mounted on the sink are three pairs of ON Semiconductor ThermalTrack 200W complementary bipolar devices for each channel's output stage, with built-in temperature sensing.

The output stages are operated in class-G, meaning that there are actually two pairs of positive and negative voltage rails feeding the output transistors. These transistors are usually powered from ±35V rails, but when the input signal voltage would lead to clipping—at around 50W into 8 ohms— MOSFET "lifters" switch to ±65V rails, allowing the signal to be amplified by the same devices up to the specified 200W without clipping. (These lifters are said to be capable of turning on and off with as much as 60A peak current in less than a microsecond.) Class-G allows the power supply to be more economically designed, as the higher voltage rails have only to be able to supply current for a fraction of the signal's duty cycle, the lower voltage rails supplying the bulk of the continuous current demanded by the loudspeakers.

A superficial reading of Arcam's literature suggests that the output devices are biased into class-A. But with an 8 ohm load, that would mean a standing current of 1.75A for each channel and a very hot-running amplifier, even if the heatsinks were much larger. Closer reading reveals that the output circuit "includes a proprietary error correction circuit that modulates the modest standing currents in the output stage and ensures a near-constant output impedance for peak currents of up to about ±4 amps, corresponding to well over 50W into 8 ohms. The P49 thus behaves exactly like a classical class-A amplifier up to this power level in terms of performance but without the heat penalty."

Listening
I wouldn't say that the Arcam FMJ P49 offers the ultimate in clarity, transparency, call it what you will—but at just under $5000, it meets a high standard in this respect. While preparing this review, I was compelled, by Fred Kaplan's piece on Stereophile.com, to buy Miles Davis's At Newport 1955–1975: The Bootleg Series Vol.4 (4 CDs, Columbia/Legacy 88750 8195 2). Disc 2 features a set from July 1966 featuring Davis's "second great quintet": Wayne Shorter, tenor sax; Herbie Hancock, piano; Ron Carter, double bass; and Tony Williams, drums. Carter starts "All Blues" at a breakneck one-in-the-bar, triple-time pace. Miles's trumpet is way out front in the mix, with kick drum and bass a little suppressed. But with the Arcam in the system, all was appropriately audible—even some print-through on the 50-year-old mono master tape.

I could readily hear the difference between Beethoven's Violin Sonata 10 in G, Op.96, performed by violinist David Abel and pianist Julie Steinberg (24-bit/192kHz ALAC needle drop from LP, Wilson Audiophile W-8315) and the duo's recording of Brahms's Violin Sonata 1 in G, Op.78 (DSD64 file, Wilson Audiophile W-8722). Both performances had been recorded with a spaced pair of Schoeps omni mikes; through the Arcam P49, both very effectively placed the musicians in the room. However, the Beethoven, made with a ReVox A77 tape deck, had a clearly warmer balance and a more amorphous stereo image than the Brahms, which was made with the John Curl–designed Ultramaster recorder.

COMPANY INFO
Arcam
US distributor: The Sound Organisation
159 Leslie Street
Dallas, TX 75207
(972) 234-0182
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COMMENTS
James.Seeds's picture

A look inside reveals sparseness I expected for $5000 US a little more meat this is something right out of an Outlaw Audio catalogue

JimCorbet's picture

Just bought this unit. For 3400 pounds you would think Arcam would be able to put some nice proper black screws on the unit. Some on my unit are discoloured and other are scratched up. Who know how the unit looks inside?

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