Audio Research LS8 Pre-Amplifier Review

All-tubed, classically ARC-styled and featuring a few touches which have filtered down from the dearer models, the LS8 joins the (thankfully) ever-lengthening list of entry-level high-end goodies…just in case you were afraid the Ref 1 pre-amp and Ref 600 monoblocks were the new norm for ARC. Which you know isn’t so if you also remembered the CA50 integrated.

It’s not that the LS8 appears to be derived from the CA50, per se. It’s neither remote-controlled nor brimming with lights, and – unlike dearer ARC pre-amps – it lacks balanced inputs or outputs. But quite where the economies were made is hard to determine. Nothing suggests that it is anything less than pure Audio Research.

Just what ‘pure Audio Research’ means in the ever-changing world of valve hardware is easy enough to define. The company is traditionalist, and has – so far – resisted the attraction of the single-ended triode; as such it embodies a sort of conservatism that contrasts with its forward-looking use of, say, microprocessors in the control sections. The LS8 is all-tube (except for its solid-state power supply), line-level-only and fundamentally minimalist. But while it lacks a balance control, record-out facility and other non-essentials, it still manages to feature an over-the-top muting arrangement, black tube damping rings are supplied as standard and it even comes with a particularly nice cross-head screwdriver for removing the lid so you can fit its four 6922/E88CC dual triodes.

With the lid removed, you see a well-made, single motherboard, carefully routed cabling and a profusion of designer components like Wonder Caps, InfiniCaps and Rel-Caps. They’ve been installed in specific locations to indicated that the caps were chosen according to their sonic suitability in a particular point in the circuit, rather than the company simply sticking to one politically-correct brand throughout.

And you will have to open the pre-amp, unless your dealer is doing the installation, because the LS8 arrives with the valves packed in a dense foam cube, placed inside the voluminous chassis. They’re marked V1 through V4, even though they’re all the same type, and a road map tells you where they go because the units are assembled and tested with a specific valve in a specific position. (I didn’t swap the tubes around to check if there was any change in performance because I’m such a trusting soul.)

Don’t worry if you lose the sheet; a close examination of the circuit board also reveals which tube base is which. Another sheet indicates that, since October 1996, all ARC products using 6922s feature valves with silver rather than grey centre sections, and each sports the aforementioned black rubbery damping ring – one only per tube! – located precisely 28mm from the bottom of the valve.

Given the overall simplicity of the LS8, the rear panel is utterly uncluttered: five pairs of substantial, gold-plated phono sockets for line-level inputs marked tape, tuner, CD, video and auxiliary, and two pairs of phono-socketed outputs marked tape and main. An IEC-style socket accepts the mains input and there’s a user-accessible fuse fitted near the AC input. That’s it.

The front panel is equally free of clutter, but the controls need some explaining. Between the black handles are two toggle switches, two rotary controls and a pilot lamp. The toggles flank the green light, the left switching the unit on or off, the right choosing between operate and mute, the mute action preventing any signal from reaching the outputs. The rotary to the left is the volume control, with its own form of muting, while the right-hand rotary chooses between the five sources.

Minimalist or not, the user should read the owner’s manual lest impatience cause a brief moment of worry due to unexpected silences. The LS8’s muting ritual begins with switch-on, when the green light flashes for around 30sec. Assuming that you’ve been a good boy or girl and made sure that the muting toggle was in the ‘mute’ rather than ‘operate’ position before you switched on, the green lamp will revert to its half-illuminated state when the flashing stops, indicating that all of the circuitry has stabilised. Flick the muting toggle to ‘operate’ and the light illuminates fully. And you hear an internal relay’s click each time the muting is activated or deactivated.

But that’s not all. The volume control also elicits a relay click when you rotate it from full off in a clockwise direction, or return it to the ‘off’ position. The click occurs around the 7 o’clock position, and there’s no way you can silence the pre-amp completely without activating this ‘back-up’ mute. With this secondary form of muting – proper muting as opposed to a volume control merely set to its lowest position – the green light stays fully illuminated, but you do still hear that same relay click as per the toggle-applied muting.

Another point worth noting about the volume control is that it’s detent-free, so you don’t feel the position where the muting kicks in; you have to listen for the relay. Additionally, ARC actually describes the volume control as providing 64 steps of gain, in 0.5dB increments for 40 steps, but the control rotates smoothly there’s no actual step-indication.

In practice, provided you follow a regime of using both the manual and automatic muting states provided respectively by the toggle switch and full anti-clockwise rotation of the volume control, you need never worry about ‘unexpected transient signal pulses’ reaching your power amplifier.

As one who’s always swapping equipment and who’s intrinsically impatient, I prefer the LS8’s offer of total muting to switching off a pre-amp at the mains every time. Note, though, that if you do switch it off, even after the LS8 has been warmed up and in use for hours, it will still go through the 30sec flashing light period when you switch it on again.

Like the company’s dearer models, the LS8 uses microprocessors to control the front panel actions. Your attention is called as well to the need to avoid discharging static when touching the LS8, which could render the controls inoperable. Should static cause the microprocessors to lock up, all you have to do is mute the LS8, switch off the power, disconnect the AC cable and wait a few seconds before plugging it in again and powering it on.

Fortunately, I didn’t get the opportunity to test this because the phenomenon never occurred during the weeks I had the unit at home, despite carpeting of dubious origin and weather (mid-December to early January) so cold that I expected flashes of static every time I made contact with anything in the room.

All of the LS8’s inputs are specified as 50k Ohm, the output impedance is 200 ohms, the unit’s gain is 12.2dB and it’s non-inverting. And while I did connect it to a variety of tubed and solid-state amplifiers, I preferred to use it with the power amp most likely to be its mate, the VT60. And for a couple of reasons.

The first is that the VT60 is one of my all-time favourite amplifiers, definitely on my shortlist if I was in the market for a sublime, medium-powered, push-pull tube amp and I couldn’t locate a mint D-70. Even in its non-SE, uglier-than-sin form, I still love the VT60. And I knew it would match electrically the LS8.

More important, though, was its accordance with the LS8’s main selling point: price. The VT60 has just had its price lowered to £1999, to reflect the only good thing that’s come from those Labour cretins getting elected: a strong pound sterling. As Audio Research’s entry-level all-tube power amp, the VT60 is a natural partner for the company’s entry-level all-tube pre-amp. Which brings us to the best news of all:

The LS8 retails for £1449. And if you’ve read this far, then it’s likely you’re not the hair-shirt fantasist sort who thinks that a pint still costs a shilling. At today’s prices, £1449 is way below the average for an all-tube, imported-from-the-USA pre-amp, especially one which behaves like the LS8.

I slipped the LS8/VT60 pairing between a Krell KAV300cd CD player and a pair of Quad ESL63s, using Discovery interconnects and Harmonix speaker wires. After switching everything on, I disappeared for an hour into the kitchen, had a cup of tea, did some writing – anything to make me forget about warm-up, having heard that the LS8 doesn’t sound good until it’s been tasting the AC for at least 30 minutes.

The results? The kind of system you only ever assemble by accident. OK, OK, so there are bound to be Krell CD players feeding Audio Research pre-amps somewhere on the planet, but Quad ESL63s don’t seem to be a fashion item except for a core of totally dissimilar UK reviewers. Normally, I prefer the Quads to be driven by tubes, so the stretch to the LS8/VT60 wasn’t all that great. But most of the time, I use the ’63s with elder British tube amps of the sub-25W variety. The VT60, with over three times the power of Quad IIs, matched rather than threatened the now-venerable electrostatic, and the cohesion from Krell to ARC to Quad was nothing short of revelatory.

It’s all down to smoothness and control. If the ESLs are abused, they complain audibly and immediately. The Audio Research components cosseted the Quads, the LS8’s acting as both an intermediary and a conductor. As the Krell is sublimely neutral and unexpectedly friendly toward tube pre-amps, all the LS8 had to do was amplify or attenuate the incoming signal.

What did it add to the Krell? Surprisingly little. As I’ve been using the KAV300cd for some time, I ‘know’ its sound and can ‘subtract’ it from the LS8. What was added was nothing more than a shade of warmth to an already ‘human’ midband, with no constraining of the Krell’s dynamic capabilities.

However tube-like the midrange, the overall sound is clean’n’lean, but never over-etched. Given that the VT60 possesses a touch of the richness which endears vintage valve amps to some of us, it was with blessed relief I noted that the very warmth the LS8 adds to the Krell’s middle did not tip the overall sound toward the overly lush. Better still, the LS8 always sounds big and wide-open, if not quite as impressive in scale or transparency as the Ref 1.

What sold me on the LS8, what makes it stand out in its price class is refinement, pure and simple. And this was an instantly revealed quality, detectable the moment the first sounds emerged. Keep in mind that I’m talking about its role in a specific system; I have no doubt that the Quad ESL63s had more than a little to do with the overall effect.

What captivated me was a silkiness, a smoothness present even when it should or might have been overwhelmed by the music. Admittedly, I kicked off my listening session with Big Daddy’s positively cuddly ‘With A Little Help From My Friends’, which out-Mathises Johnny, but the gossamer delicacy and the sense of air was present in over-engineered studio confections, live material and even mono transfers.

It is to my probable shame that what I’m describing, what I’m praising is a form of artifice, of niceness, of aw, shucks-Jimmy-Stewart affability which results in the easiest of listening. Given the stresses of Christmas, the pressure of getting ready for CES and the worst winds since ’87, maybe I needed it like a cup of Ovaltine on a cold night. But so what? It sounded just as sweet the morning after and in a radically different system using tranny amps and small dynamic speakers. So, by my reckoning, the Audio Research LS8 is – this early into 1998 – one of the bargains of the year. And probably the sweetest way yet to move from being an ARC wannabe to an ARC proud-to-be.

(Hi-Fi News, April 1998)