Audio Research LS2 Line Stage Preamp Reviewed

Published On: February 13, 1991
Last Updated on: October 31, 2020
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Audio Research LS2 Line Stage Preamp Reviewed

A hybrid preamp that uses a single 6DJ8 tube and FET devices, the LS2 is one of the preamps that helped define Audio Research's reputation as the premier tube electronics manufacturer. Superb-sounding and ergonomically austere, the LS2 is a special preamp.

Audio Research LS2 Line Stage Preamp Reviewed

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Price points plummetting like pebbles in a pond. Okay, maybe I forced the alliteration, but you've just gotta wax poetic when the cost of audio ecstasy drops -- and substantially to boot. The remaining digits on the sticker are still four figures, still beyond the reach of many, but I consider the halving of the tariff for the state of the art to be something worth celebrating.

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And which company is the source of this largesse? Would you believe Audio Research, every valve lover's champion? Cautious and slow the company may have been before addressing the needs of the Digital Age, but they've shown what a wonderful DAC they could produce, along with line level pre-amps which best serve those who've moved to digital (or line level) sources. And the LS2, the company's second line-level-only pre-amp, re-writes the books.

Sure, there's only a lone tube under the lid, and those who still won't give up their glass-filled SP-10s and SP-11s will probably think of it as something close to heresy. But Audio Research has always denied any tube-mania. The company line is that it'll use whatever is necessary to build the best products it can.

So the LS2 is a hybrid, all solid-state save for a 6DJ8 (ECC88) dual-triode. The power supply is all solid-state, while the rest of the audio circuit is of the FET persuasion. But that one bottle is enough for some of us who like to think in incandescent terms, so let's leave it at that. Despite what a certain other organ has suggested, tubes still have an important role to play in the high end, and that's not open to debate.

The LS2 is quite simply the best sounding pre-amp Audio Research has ever produced. This does not mean that its predecessors are therefore obsolete (I'd give up even my '52 IWC Royal Navy Chronometer for a mint SP-10...well, almost) nor that ARC should dump the '9, '14' or '15. That's because the LS2 is minimalist and I know plenty of sane hi-fi users who couldn't live with the austerity. I know that I couldn't because my life as a reviewer would be made all the more dificult if I had to shed even one of the facilities on the 'almost loaded' SP-14.

What remains on the uncluttered fascia are only a bit more than the barest of essentials. The loud pedal is a rotary, metal-film control with 41 steps and it feels nice and precise. The input selector

chooses between tape, tuner, CD, video and auxiliary, the selected signal talking to the tape outputs when the tape/defeat toggle is set to 'record'. Another toggle controls power on/off, while a mute/operate toggle shorts the main outputs of the line stage; I always useI forced the alliter

the mute when turning the LS2 on or off, 'just in case'. As with the SP-14, a two-stage green LED indicates operating status, a dim glow right after switch-on or when mute is engaged and a bright glow when the LS2 has been on for around 45 seconds or mute is disengaged.

The defeat/normal switch is a handy hot rod device which allows the user to select between convenience and optimum performance. The direct inputs at the back bypass the selector; the rest travel through it. This switch chooses between the wholly independent inputs (which cannot be fed to the tape loop) and the conventional inputs.

All socketry at the back is gold-plated and of audiophile standard, as you'd expect. In addition to phono-type outputs, the LS2 also offers balanced operation via XLR connectors. I'm still not entirely convinced that balanced operation is as major a leap forward as, say, caffeine-free cola or coloured condoms, and I know it won't make me popular with such esteemed designers as Jeff Rowland, Dan D'Agostino, Flemming Rasmussen, Glen Grue or any of the other high end honchos. But I did use balanced configuration when running the LS2 with the Classé DR-10s, so at least gimme 'A' for effort.

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Slotting the LS2 into the same spot as occupied by its sibling, the SP-14, was a revelation. Running it with CAL Tempest II SE and Marantz CD-12 CD players, Day-Sequerra tuner, Aragon 4004s, Classé DR-10s and Apogee Divas, I experienced, first and foremost, a gain in transparency greater than from any other pre-amp swap in my experience. No, I'm not saying that a leap from an aged Dynaco PAS-3 to a Gryphon wouldn't be drastic; I'm talking about products of similar merit. The LS2 made my treasured SP-14 appear slightly cloudy -- it is, after all, no slouch when it comes to clarity -- and the overall consistency of the LS2 seemed more 'of a whole'. Why this should be I'm at a loss to say, but it suggests that Audio Research's ongoing research into component quality, power supply development and topology is paying off in spades. Indeed, topology refinement is one of the key areas which separates this product from the LS1.

The LS2 is hard to describe because it lacks a distinctive sonic fingerprint, which is as it should be: the better a hi-fi product, the less it will impose on the signal. The LS2 is in no way a throwback to the flawed but lovely sound which exemplifies valve equipment. And because of this, it reinforces ARC's attitude about using what's best for the job rather than aligning one's designs with a particular school of thought.

But however much one might wish to down-play the thermionics, this is one high-emotion performer. For all of the precision, detail and 'colourlessness', the LS2 
laughs and cries and sighs and wails with abandon. Naturally, no concoction of nuts'n'bolts'n'resistors'n'wires comes complete with its own soul; the secret is in not stripping the music signal of the subtleties which contain the emotion within the performance. Far from stripping the music of ambience and warmth, it showcases these aspects.

Which is a bloody pretentious way of saying that the LS2 does less to the signal than any other pre-amp I've ever used. It quite simply amplifies it for driving a power amp, not getting in the way. Every single parameter by which we judge stereo reproduction 
for the job rather than limitingto a philosophy. With ech we judge stereo reproduction, the LS2 is something of a champion. The soundstage is wider, deeper, more open and more focussed. Dynamics? Unbridled. Frequency balance? Consistent from top to bottom -- so much so that I could readjust the Apogee DAX crossover to even flatter settings.

The opening paragraph and the promise of lower pricing refers to the LS2 versus the SP-15. This baby is #2790, roughly half the cost of the SP-15. When the recently launched phono section is added to it for systems blessed with LP playback, the cost is still below that of the phono-equipped SP-15. The '15, one of my all-time faves, will stay in the catalogue because it offers operational niceties which many still appreciate. But I think the die-hard, minimalist purists are gonna make the change. And in droves.

Don't kid around. Please tell me that 'LS' stands for 'luscious sound'.

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