Audio Research Reference 250 Monoblock Amplifier

Solid-state power amplifiers,
Tubed power amplifiers
Audio Research Reference 250 Monoblock Amplifier

William Zane Johnson, God bless him, may be gone and his path-breaking company, the Audio Research Corporation, may now be owned by an Italian holding company, but in spite of the loss of its founder and the change in proprietorship (which, let me be clear, has not affected the way things are done at Audio Research—all of whose products are still manufactured in the good ol’ USA), ARC has done anything but lose its way over the last few years. Indeed, its electronics are better than ever.

Take the Reference 250 monoblock amplifier for example.

ARC has been designing, building, and marketing a roughly 200W amp for decades (its reputation was, in part, made by the D150, the first “high-powered” Audio Research amplifier), but it has never built a better one (I've heard) than the new Ref 250, which is everything that its most recent predecessors—including the Reference 210—were not.

I reviewed the Reference 210 and, like all contemporary Audio Research amplifiers, it was an excellent pentode power amplifier. It had the traditional ARC virtues of neutral balance, lifelike bloom, and mid-to-treble range air and light, plus, like all ARC products from the SP-3 on, it was able to “breathe” life into instruments and voices in the midband and top end (almost like an acoustic bellows), changing image size, projection, and presence with the ebb and flow of dynamics (just as instruments and voices do in a concert hall).

However, all you had to do was compare the Ref 210 side by side (as I did) with a really good triode amplifier, like the then-current Convergent Audio Technology, to hear what the ARC amp didn’t do. In spite of the fact that at 90W the CAT amp was, on paper at least, half as powerful as the Ref 210, it simply blew the ARC out of the water when it came to transient speed, dynamic range, mid and low bass definition and slam, density of tone color top to bottom, image focus, and ultimate SPLs. Of course, Class A triode and Class AB pentode amplifiers (and the different tubes they use) have fundamentally different presentations (the CAT for all its dynamo-like power and gorgeous tone color lacked the midrange-to-treble bloom, air, and lifelike “action” that I just commented on); nonetheless, the Ref 210 sounded like a wimp beside the CAT. It was also considerably grainier than the triode amplifier, producing sonic images that sounded the way “half-tone” photographs look (where the CAT’s images sounded the way “continuous tone” images look).

If you were to combine the virtues of the CAT amp with those of the Reference 210, while subtracting the flaws of each and adding even higher resolution of low-level detail and lower noise than either was then capable of, you would end up with something very close to the sound of the new Reference 250. Everything that I didn’t like about the Reference 210—its dynamic wimpiness (which made it sound a lot less powerful than its on-paper watts would suggest), its graininess, its washed-out tone colors (particularly in the crucial power range from about 100Hz to 500Hz), its slightly sluggish (by comparison) transient response, its lack of bottom-bass definition and slam, its ill-focused images (too big with too little edge definition), its inability to play really loud without bumping its head against an SPL ceiling—is gone. Everything I liked about the Reference 210 (and other pentode ARC amplifiers)—their neutrality, their bloom, their air, their light, their incredibly expansive soundstage, and, above all else, their realistic way of breathing life into instruments and vocals (now including bass-range instruments, as well)—has been improved upon.

The net result is simply marvelous—an amp that comes closer to sounding “realistic” on more instruments and on more kinds of music than any previous ARC amp I’ve heard (and I’ve heard them all, save one). Indeed, I would have to say that, ultimate power levels aside, the Reference 250 is a substantially better amp than the Reference 610T that was my reference for many years.

What’s changed? A whole bunch of things, chief among which are the power tubes (now KT120s), the power supply (greatly beefed-up in capacitance), the capacitors ARC is now using (Teflon), and the circuit designs (which, like the Reference 5 SE—another great step forward for ARC—borrow heavily from the all-too-short-lived, two-chassis Reference 40 Anniversary preamp that was one of ARC’s great masterpieces).

I will have a lot more to say about the Reference 250 (and the Reference 5 SE) when I review both in an upcoming issue of TAS. But until then, take my word for it: This is an amp that you need to audition, whether you’re in the tube camp or the solid-state one. It competes fully with the best examples of either gain strategy, even in those areas (bass, low-level detail, speed of attack, noise) where solid-state has traditionally reigned supreme. This does not mean that the Reference 250 is the only great amp out there—we are, in case you missed it, living through a new Golden Age of High Fidelity that, particularly when it comes to low noise and high resolution, leaves most of the products from that first Golden Age in the dust. What it does mean is that when it comes to contemporary tube amplification and preamplification, ARC is the marquee to beat. But then what’s new about that?