Audio Research SP16 Tube Preamp Reviewed

Published On: January 4, 2009
Last Updated on: October 31, 2020
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Audio Research SP16 Tube Preamp Reviewed

The SP16 from Audio Research is a bit of a departure for the Minneapolis based brand in that it lacks a lot of Audio Research's trademark visual style, possessing no chunky black rack handles or WWII era control knobs. However it does sport a fancy new remote and connection options not usually seen on a tube based preamplifier at its price.

Audio Research SP16 Tube Preamp Reviewed

By Author: Home Theater Review
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Audio_Research_SP16_preamp_Reviewed.gifThree words to warm to cockles of any tube lover's heart: Bill Is Back. William Z. Johnson, the mastermind behind some of the greatest valve amps and pre-amps of all-time, has come out of retirement, and the good news starts here. Among the first products of the ARC rebirth are two 'affordables', both of which hark back to earlier models without reeking of retro. And both tackle the cries from the faithful, particularly those who simply ain't aspiring to Reference 600s.

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This month, we look at the pre-amp; next month, the matching power amp. Trust me: your patience will be rewarded, for the two products - despite dealing with 21st Century concerns - were designed with both analogue and cost-effectiveness in mind. It's been nearly six years since the last affordable, phono-equipped ARC pre-amp was discontinued, the fondly-remembered SP9, and I've been reassured that there's been a clamour for an affordable, full-function Audio Research preamplifier with an integral phono stage to replace it. Enter the SP16, and a bit of 'Importer's Two-Step' to address the psychotic British fixation with price points.

As if to contradict the analogue goals which inspired it, while addressing at the same time an era in which CD and other digital sources dominate, the SP16 will also be available in line-stage-only form as the SP16L. Sensible, you might rightly think, given that plenty of people don't even know what an LP is, but that would be to ignore the stupidity which rules the British market. In order to keep the package price of an SP16 preamp and its partnering power amplifier £100 below a nice, round figure, the SP16 in line form saves a crucial £400 over its phono'd sister. Considering that the majority will fly out of the shops with the phono section - Audio Research customers tend to prefer music to digitalia - that round figure will be exceeded in most cases by £300 regardless. Aaah, the mysteries of pricing!

As this product and its sibling represent a form of 'comeback', the company was careful in its juggling of old and new, starting with the nomenclature. 'Our rationale for labelling this unit the SP16 is simple: it is the first new full-function preamplifier, with an integral phono stage, introduced since the SP14 and SP15.' The SP16 incorporates 'classic tube architectures for both line and phono sections', while at the same time offering enough flexibility, and enough in the way of modernity to fit into multi-role systems which also deal with, say, extra zones or home theatre. The SP16 is equipped with five sets of inputs marked Phono, CD, Tuner, Video and Aux, two sets of main outputs, tape out and a processor pass-through - something which seems mandatory these days for two-channel products. Additionally, there's a 12V trigger to turn on power amps or other equipment, and full remote control of power, input selection, stereo/mono, volume, and muting.

There are - I must admit - two things that I miss about earlier SP-series units: rotary controls and toggle switches. OK, OK, wanting to twist a control instead of tap-tapping to increase or decrease level is something to get used to, and having to scroll through inputs isn't as big a sin as, say, dual-mono volume controls à la Croft. But one thing I didn't know, something which is crucial to the understanding of the SP16 design goals, is that rotary controls (of ARC's standard that is) would add substantially to the price. And while everything has been pared down with cost-effectiveness in mind, the quality of the components and the performance have not been compromised. So, bye-bye costly rotaries, bye-bye handles, bye-bye toggle switches.

On the right side of the front panel are the six 'soft-touch' buttons for Power, Mute, Processor, Input and Volume Up/Down, matching the control buttons on the CD3 - a likely partner for the SP16. In an identical cut-out on the left, where the CD3's tray would be, is an LED display indicating which input was selected, and whether or not processor, mono and mute are in use. Below it is a visible-across-the-room row of LEDs numbered 1-20, illuminated one at a time, for volume indication. Despite the lack of handles, toggles and rotaries, it's still unmistakeably an ARC product. And at 17.75x5.2x10in (WHD), it's unusually compact for an ARC product.

Inside, you could be looking at a pint-sized version of one of the much dearer units. The outer trappings may have been minimised, but the innards include the same expensive PCBs with extra-thick copper circuit traces, point-to-point wiring and hand-soldering. The SP16 is a pure Class-A design with all-valve gain in the line and phono sections, via a half-dozen selected 12AX7 tubes - three in each circuit. Audio Research tells us that these are a newly released type of which they '...are enamoured' because of their sonic abilities, and because 'they allow the circuit topology to remain simple while providing high gain.' Other circuit details include regulated power supplies with a total of eight high- and low-voltage regulators, high-energy storage plate supply, the company's patented DEC filter cap decoupling, high performance input-selection relays to allow for short signal paths and a very precise, digitally-controlled, analogue-switch, 70-step volume control.

Low-impedance, cathode-follower main outputs allow the user to drive two power amplifiers simultaneously - great for bi-amping or running a second zone. The gain for the line inputs is 12db, while the total gain from the phono input to the main outputs is 54db. Although suitable for moving-magnet and high-output moving coil cartridges, it falls just short of providing the requisite oomph needed for low-output types. I used it with a high-output Grado, but added an Ortofon transformer to the mix when using the Linn LP12/Ekos/Arkiv combination.

While the SP16 was inserted into my regular system consisting of Wilson WATT Puppy System 6 and Marantz CD12/DA12 (in addition to the Linn front-end), with power amps including the Quad II-fortys, Radford STA-25 and Dynaco ST70, something wonderfully unexpected happened purely by coincidence. For whatever reason, a pile of review components arrived all at once, some four months' worth; clearly, the Editor wanted me to write reviews in advance of the summer holidays. And, sure, it was a no-brainer that I would hook up the SP16's matching amp - the VS55 - and it was all I had hoped it would be. The added shocker was Sonus Faber's Cremona, which isn't even scheduled for review until September. But it was An Audio Moment, one of those rare instances when a mating you couldn't foresee just, well, happens, like Krell/Apogee or Campari/soda or Laurel/Hardy.

Everything simply fell into place, utterly complementary in every respect. Tonally, spatially - even the VS55's wattage suited the Cremonas to perfection. Reeling from this discovery (just add a CD3 and you'll hear why ARC/Sonus Faber dealers are gonna have an easy time of it), I found it hard to return to the discipline of isolating the pre-amp's performance from the whole. But needs must, so I also tried the Quad QC-twenty-four, Radford SC22, Dyna PAS3 and Musical Fidelity Nu-Vista.

What I thought I knew about Audio Research pre-amps fell by the wayside. Even though I had recently been treated to sessions with the latest Reference 2 in the SME room, I wasn't quite ready for the sound of the SP16. Would it be lush and vintage? Achingly, nakedly modern? Somewhere inbetween?

Let's dispense with the operational elements: I quickly stopped missing the toggle switches and the rotaries, though they remain my preferred modes of access. I left the unit powered but in stand-by during the breaks between sessions, so warm-up took little more than the 30 seconds of the muting period prior to the unit going 'active'. But it does get better as it warms up even further; only you can decide whether or not, as the owner's manual instructs, to leave it on at all times and thus shorten tube life.

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So far, so good: a painless pre-amp with a helluva fine phono section. Even allowing for the need for medium-or-higher output cartridges, the phono stage has plenty in the way of dynamic range, with a low noise floor, a freedom from tube artefacts and lots speed. Transparency matched that of the line sections, so it's clear that Audio Research paid extra attention to modernising the phono section to appeal to 21st Century ears. It's worth noting, however, that the transparency is of so high a calibre that you will notice the intrusion of a step-up - extra leads not the least part of the compromise - so SP16 owners will probably gravitate toward high output cartridges by natural selection.

Key elements of ARC-ness found readily in the SP16 are openness, coupled to a sweet top end, the latter leading me to feed it disc after disc of female vocals. As I'm currently suffering a bluegrass jag, it meant loads of Dolly Parton and Alison Krauss, with forays into country warblers such as Crystal Gayle. In every case, these voices demand clarity, and this pre-amp is so exceptionally texture-free that it put me off my fave vintage pre-amps. An unexpected benefit, however, especially odd given my loathing for cable testing, was the way that the unit's behaviour showed up cable differences with almost breathtaking immediacy. And to discern differences between, say, two grades of Kimber within a 10 seconds play is something to covet.

And yet there's nothing at all clinical about the experience. Modern-sounding and analytical it may be, but without the martinet stance of today's best solid-state pre-amps: you simply cannot accuse it of being hygienic. But here's the burning question: Is the SP16 reminiscent of the ARC preamps which inspired it? Suffice it to say, audio memory ain't all that reliable, but I would suggest that the SP16 leapfrogs backwards, over the SP9, SP14 and SP15 to Johnson's greatest achievements: the SP10 and SP11. It shows traces of their warmth and emulates their glorious soundstages, while emulating their precision.

So am I describing a missing link between the highly collectible SP10/11 and the current LS25...let alone the Reference 2? 'Fraid so. Which makes the phono version of the SP16 a astonishing bargain at 2499, and the line version SP16L a veritable steal at 2199. So, join with me on a count of three: Welcome back, Bill.

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