Audio Research DAC2 Digital to Analog Converter Reviewed

Audio-Research-dac2-review.gifDeath, taxes and the Audio Research Corporation — the three things I can count on no matter what. Ever since I first coveted an SP-3, reviewed a D-70, acquired an SP-9, then an SP-14 and a DAC1, I’ve found the presence of at least one of the Minnetonka Marvels to be something reassuring and constant. Which is amusing when you consider that ARC was once so guilty of upgrade-itis that the list of model suffixes read like alphabet soup. Then again, that was when high-end audio was such an active, controversial hobby that you could do all sorts of silly things, like pander to unstable gurus. Now that the high-end has matured and toughened in the face of economic realities, ARC has emerged as one of its more dependable elements. You can almost imagine the staff attending anti-political rallies, actively fighting the perilous path of fashion which gives a rating in hi-fi’s Top 10 about as much shelf-life as a doner kebab.

Which means that ARC hardware can be thought of as an investment, and you don’t really have to rush down to your local hi-fi emporium if and when the company does announce an upgrade. My SP-14 is a very early one, changed after three-and-a-half years only by the substitution of a new valve for the original. And yet I have no desire to part with the ’14 or trade it in for a newer one. The point I’m making is that ARC, once upon a time exhibiting as much of the high-end’s self-destructive tendencies as any other brand, has become one of only four or five makes which have risen above high-end lunacy. Which leads us to a complete ARC system which illustrates this (almost) conservative approach to perfection.

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Remember that ARC has a long history as the most valve-supporting of all the serious manufacturers. And yet it employs transistors when necessary. Talk to Terry Dorn or Bill Johnson and you won’t detect a trace of religious fervour when you mention tubes. The attitude is simply ‘Use a tube if it’s the best solution to the problem.’ So the middle-of-the-catalogue package under scrutiny is two-thirds solid-state — but you wouldn’t know that if you weren’t told so. The sound is pure valve.

Externally, this is all classic ARC: silver with black handles, recessed knobs, delicate toggle switches, green tell-tale LEDs, laboratory-chic right down to the…whoa, there. Something has changed. Gone are the pre-drilled slots for 19in rack-mounting. Not to worry; I’m probably the only jerk in the hi-fi community who ever used them, even without owning one of the company’s gorgeous, bespoke rack units.

For £3840, you get no nonsense; the DAC2 is about as simple as they come. Its front panel contains only an on-off switch and indicator, polarity inversion, a ‘lock’ indicator and a selector for one of the three sources and therefore identical to the now-discontinued the DAC1-20. At the back, things have progressed to accommodate both the latest transports and balanced operation. The three inputs include AT&T and TOSlink optical for inputs 1 and 2, while input 3 is switchable for either BNC or AES/EBU non-optical data transmission. Digital output is via TOSlink. The line-level output is accomplished with either RCA unbalanced or XLR balanced. (I was not able to use the latter because the LS3B has only unbalanced inputs.)

Firmly a multi-bit device, the DAC2 features an UltraAnalog 20-bit DAC with x8 oversampling as used in the DAC1-20. It differs from its predecessor with an all-new digital receiver for better jitter control and an all-new analogue section using the company’s latest approaches to power supply regulation; this is what makes an uprated DAC1-20 a Mark II and not a DAC2.

Austerity does not apply to the affordable LS3B, which — from ten paces — is hard to distinguish from other ARC line-level-only pre-amps. Across the top, four rotaries for gain, balance, mono/stereo and a selector to choose from five main inputs. Below the knobs is the recess containing on-off, mute/operate, a green tell-tale, direct/normal input and source/tape monitor. The direct switch accesses a wholly separate, sixth input which bypasses much of the control circuitry for purist listening. Around the back, it’s all-gold phono socketry, but with two sets of main outputs as well as the XLR ‘balanced’ output which makes this an LS3B selling for £2149 instead of an unbalanced LS3 for £1593.

The LS3/3B replaces the popular LS1as ARC’s entry level line-amp. It’s a solid-state design in which simplicity has been made a prime concern. The result? Ultra-short signal paths and a minimum of wiring. DC-coupled inputs and a tightly regulated power supply are also part of the recipe as is the company’s patented Decoupled Electrolytic Capacitor circuitry first featured in the dearer models. Yet that ‘B’ suffix doesn’t mean true balanced operation but balanced-style output socketry. The LS3, unlike the truly balanced LS2, is a single-ended design; ARC added a phase splitter, whacked on the XLRs and thus made the LS3 suitable for use with XLR-input-only power amps, such as the new V-Series units. But it’s not just an expensive socket change, for the LS3B does enjoy an extra 6dB gain in output and it is quieter — if not so quiet as a fully-balanced design. (I did my RCA vs XLR listening through the Classe DR-10 just to make certain that the extra dosh paid for more than sexy hardware.)

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Audio-Research-dac2-review.gif

And you will want to use something suitable for the V70 power
amplifier because it just may be the best amp the company has ever
produced. I can’t remember who noticed it first, but there’s a belief in
certain high-end circles that the best-sounding amps of all-time have
tended to be sweet little 60-100 watters. Power doesn’t enter into it,
and you’re faced with natural restrictions regarding speaker choice, but
there’s much to support that argument. Whatever, the V70 — rated as
’60W minimum continuous at 16 ohms from 15Hz to 20kHz — is sized and
priced ( 4299) as a middle-to-esoteric model, unable even to look at 2
ohm behemoths, nor can it fill a room much larger than ‘normal’ unless
it’s wired to a hypersensitive speaker such as a true horn.

Its power comes from eight KT90s (though I could have sworn that the
review unit’s tubes said ‘KT91’), representing the latest generation of
substitutes for the 6550 and KT88. And I’m mildly concerned about this
profusion of KT-prefixed ‘new’ tubes. Why? Because Americans have
embraced them with open arms while every UK tube maven I’ve spoken to
has been cynical to say the least, with stories about container-loads of
pre-Serb/Croat War Yugo-tubes needing to be cleared out of certain
California warehouses. Suffice to say that the V70 sounded wonderful, so
I don’t give a toss what numbers appear on the glass. Amusingly, the
company allows for tube substitutions with bias adjusted accordingly;
alternatives listed include the 6550, 6550A, KT88 and KT100.

Using hybrid circuitry, Audio Research has produced this mid-power
design as a lineal descendant of the Classic Series models of a couple
years ago. In addition to using triode operation and ARC’s cross-coupled
circuitry, the V70 is balanced throughout. J-FETs make up the input
section with MOSFET followers feeding 6FQ7 dual triodes directly driving
the output valves. Soft-start switch-on and shut-off prevent any
unwanted thumping; you’re reminded of this by the 30-second delay which
allows the tube heaters to rise to the correct voltage while the bias
supply stabilises. Then there’s a two-second ‘ramp up’ of the B+ supply
voltage for normal operation; the sequence operates in reverse at
switch-off for negligible strain on the tubes.

User interaction with the V70 is minimal. The fascia bears an on-off
switch, flanked by tell-tales for power-on indicators (one of which
flashes while the switch-on delay occurs) and fuse caps. At the back are
the XLR inputs and screw terminals for the speakers, which ARC
continues to prefer over binding posts. Your only intimate moments with
the V70 will occur when you unpack it, unless your dealer has enough
class to install it for you. The tubes are packed separately, along with
a basic toolkit. Unscrew the cage, fit the numbered valves, connect the
cooling fans and you’re ready to rock. That’s it.

Well, not quite. Even the solid-state DAC and line amp benefitted
from a reasonable warm-up period, a good 30 minutes being sufficient.
Amusingly, the gains over that first half-hour are minimal, and even
ice-cold this set-up sounds special. The DAC2 betters its predecessor in
one key area, that of delicacy and all it implies. Its benefits include
clearer resolution of fine detail and ambience and some of the best
‘3D’ I’ve ever heard. But be warned: the DAC2 is not an in-your-face
performer and other DACs may be preferred for their greater weight and
impact. What makes the DAC2 a stand-out among similarly-priced
converters is its overall coherence; transistions from bass to mid to
treble were smooth and consistent, with no change of character. And
it’s a natural for the LS3B, which possesses a nearly identical
personality.

Even though this collection of components is being assessed as a
system, I had to employ other devices for comparison’s sake. Transports
included the Krell MD20, the Marantz CD12 and — for a laugh — the
transport section of the budget Marantz CD52 Mk IISE. Which acquitted
itself beautifully, by the way. Although the LS3B sounded most
comfortable when fed by the DAC2, interesting ‘tailoring’ was possible
with the Vimak DS1800 DAC (greater impact) or the Krell Studio (richer,
smoother lower registers), which I used as necessary…according to
speaker selection. And this is important in the context of the V70,
because it has extremely limited operating parameters. Which means
limited speaker selection.

In a nutshell, the V70 hates low impedances. I assumed that the 4ohm
Sonus Faber Minima Amator would prove a perfect mate. I was wrong. When
the V70 clips, it sounds spongy, the bottom end falling apart before the
treble. And with powerful bass from pieces such as Mel & Tim’s
‘Carry Me’, the limits were reached even though the listening levels
were far from Wayne’s World suitability. So I moved to the Apogee Stage.
Another mistake. Then the JBL L1. Sweet as a nut, but not quite up to
the mark for resolving the imaging I heard the V70 yield through the
Minimas. What to do?

Hmm…the spec sheet said 16 ohms. There’s even a tap for this
rarely-used impedance. And there, not three feet from my desk, are the
LS3/5As. Dare I audition a 10k-plus system, less CD transport, with a
speaker selling for under 500? The NBS cables used throughout cost more
than the baby Beebs. Aah, what the hell. Who’s it gonna upset?

Put another way: anyone who doesn’t grin in admiration from ear to
ear upon hearing the V70-plus-LS3/5A should go buy a Sega. Talk about
sweet soul music — Arthur Conley, where are you in this hour of need?
Despite cabinets small enough to stack in the stockroom with Nikes and
Reeboks, despite a basic design nearing its majority, the LS3/5As let
the V70 work without worry, like not asking a road car to compete in a
Grand Prix.

Plenty of level for this non-headbanger. Sympathetic lower registers.
A friendly impedance. So much for the practicalities. But the sound?
The midband was simply gorgeous, working so well with male and female
vocals that I left the Starting All Over Again CD on repeat play for
three hours. The girl-group backing in ‘Wheelin’ and Dealin” came
through loud and clear and positioned behind the frontmen. Off at an
angle, no less. Moving to B.B. King’s ‘Don’t Get Around Much Anymore’,
the system dealt with the wide dynamics despite specs which say that it
just can’t happen. Are we talking about miracles when a 2x60W tube amp
and some tiny monitors put B.B. King right in your room?

I think not. Miracles have nothing to do with it. We’re talking,
instead, about a package you’re unlikely ever to be offered by a
conventional, nervous, tradition-bound retailer, a combination as
bizarre as a peanut-butter-and-banana sandwich. Which anyone who’s ever
tried it will tell you is absolutely delicious. What this system
represents is true high-end performance without size penalties,
superlative use of digital hardware dovetailing with the romance of
tubes. There are other ways to spend five figures, most of which will be
regarded as more ‘sane’; I reckon this ARC set-up will become something
of a fave with users of ‘easy’ electrostatics. But an ARC set-up with
LS3/5As is one that’s guaranteed to bring a glow to your cheeks. And I
don’t mean by having you rest your chin on the tube cage.

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