TAS 194: Naim Audio SuperLine Reference Phonostage

Equipment report
Naim Audio Superline Phonostage
TAS 194: Naim Audio SuperLine Reference Phonostage

It could be argued that high-end audio components have personality traits similar to those of their companies’ founders. While specific examples abound, let’s consider just a few from our most auteur-driven companies. Even if the founder wasn’t always the actual or sole designer, who can think of the finest Audio Research gear without also thinking of William Z. Johnson; a massive Krell amp conjures Dan D’Agostino; Magico speakers certainly reflect Alon Wolf’s perfectionist streak; while Dave Wilson’s background as a recording engineer and quest for excellence is apparent in every Wilson Audio design.

And nearly a decade after his death from cancer, the gear built by Naim Audio continues to reflect the imprint of founder Julian Vereker. Although he had a forceful personality and a wide-ranging love of life that drew him to non-audio activities such as auto racing, sailing, and bicycling, Vereker’s Naim electronics never seemed to draw attention to themselves, but instead always seemed to exist in order to serve the music. Indeed, with their ultra-minimalist black-box chassis, one could say they were designed to be the functional opposite of the proverbially perfect child—heard but not seen.

But looks can be deceiving. Nestled within these plain albeit handsome-looking boxes is some serious engineering that extends across Naim’s surprisingly vast product range. While most TAS readers are familiar with the hugely popular and terrific-sounding Nait integrated amp (the latest version, the 5i-2, sells for $1450), Naim components hit many price levels before stopping at the relatively lesser-known Reference series, which can reach $20k per component. That’s a lot of jack under the best of times, let alone one in which that figure might equal the latest hole blown out of your 401(k). Of course, Naim’s price points are complicated by the fact that, unlike most gear, Naim’s can be upgraded by a choice of outboard power-supply options. And trust me, as you step up the level of power supply the sonic rewards are not only easily audible, they spell the difference between good and frickin’ wonderful.

If we apply this thinking to the company’s $2950 SuperLine Reference Phonostage, which, in order to isolate noise, contains no built-in main power supply, owners have four options for siphoning in electrical juice. One is by way of piggybacking the SuperLine to a Naim component of similar performance; either a preamplifier or the SuperNait integrated amp ($4450) via Naim’s SNAIC-5 connecting cable. The other is to mate the SuperLine with one of three standalone Naim power supplies: the FlatCap2x ($1100), the HiCap2 ($1900), or the SuperCap2 ($5950).

For my evaluation, Naim USA, which recently became part of the Audiophile Systems Group, supplied a HiCap2 and SuperCap2 for evaluation purposes. And while $5950 for a power-supply upgrade may have you questioning its value, the SuperCap2 transforms the SuperLine from very good into one of today’s finest phonostages, right up there with perennials like the Manley Steelhead and the battery-powered Sutherland PhD. But before we talk sound, let’s take a peek inside.

In a chassis measuring 8" wide by 12" deep, and just over 3" tall, the SuperLine contains a key feature that Naim borrowed from its upper-end CD players and preamps, a weighted floating circuit board—or “high-Q spring suspension system”—that isolates the design from environmental vibrations. Naim says this is a first in a phono preamp. A pair of transit screws ensures stability during shipping; I suggest leaving them in place while connecting your cables, because it’s much easier to plug things in and out when the rear panel isn’t jiggling around.

The unit’s RIAA phono equalization is semi-passive, while amplification is delivered via a two-stage, single-ended discrete Class A circuit coupled to what Naim’s literature calls 25 “internally regulated” power supplies.

Impedance matching for different moving-coil cartridges is handled at the back of the chassis, by means of four resistive and three capacitive load plugs, which provide twenty total load combinations. In the unlikely case that these won’t match your needs, custom configurations can be ordered through your Naim dealer.

Tonearm connections are provided for both RCA and BNC connectors, and, in an ultra-minimalist touch, there are no controls whatsoever on the SuperLine’s front or backside, not even an on/off switch. That control, of course, is to be found on whichever power supply you choose.

By the way, it should be noted that the SuperLine accepts only moving-coil cartridges, which for the majority of high-end turntable-users out there should not prove to be a limitation.

It should be further noted that the SuperLine takes an unusually long period of time to “break in.” While it sounds nice enough from the get-go, it grows noticeably better over the first three-to-four weeks. And I don’t think I’m exaggerating to say that the sound continues to bloom for several months before settling into its own. (For more details on the design, see my sidebar interview with Naim’s chief engineer, Stephen Sells.)

One thing you will hear right away, whether it is fully “broken-in” or not, is the SuperLine’s most immediately notable trait: a very low noise floor. Other reviews have touched on this deep sense of silence; this lack of electronic grunge and hash is a characteristic shared by most of today’s top-tier components. I would go so far as to term the SuperLine’s silence as “CD-like,” in that dynamic shifts can literally be startling.

So for instance, when Claude Desurmont’s birdsong-like clarinet announces the opening movement of Messiaen’s Quartet for the End of Time [Deutsche Grammophon], weaving an otherworldly theme with Daniel Barenboim’s piano, the sense of mystery, of sound almost being born anew out of thin air, is immediately riveting as well as slightly jarring. The dynamics here shift delicately, so when the piano crashes down at the start of the second movement it’s enough to make you jump from your seat, even if you already know this beautiful composition.

Of course, all music benefits from being played against such almost spookily silent backgrounds, and with such a wide range of dynamic expression. Check out Classic Records’ thrillingly realized reissue of The Who’s Tommy. As the acoustic guitar-driven “Overture” unfolds, layering rich instrumental textures as it builds—horn, organ, piano, voices, bass, and Keith Moon’s incomparable drumming—you may find yourself, as I did, pulled into the drama of this rock chestnut in a way you never imagined you would be ever again. And as the ending flourish yields to Pete Townshend’s intense acoustic guitar break, its presence is such that his blisteringly hammered instrument seems to be the only thing in the room, tightly focused and yet occupying a cavernous stage­ to the right—until Roger Daltrey’s voice pops out of nowhere, hard stage left.

We audiophiles sometimes place too much importance on soundstaging, especially since what’s captured on records is largely an artifact of the recording/mastering process itself. Yet there’s no doubt that a large, open, and three-dimensional sense of an acoustic space occupied by a virtual band or orchestra can not only be a very exciting thing to hear, but can also make our stereo system’s magic trick that much more magical.

So be it something like Tommy, Roberto Gerhard’s astonishingly well recorded Astrological Series [Decca], an LP whose sense of layered space and instrumental “thereness” will cause your jaw to drop, or the intensely present-sounding recent ORG reissue of Coltrane at the Village Vanguard, the SuperLine does a most impressive job conjuring these events in your listening room.

In addition to its silence, transparency, and dynamic excellence, the SuperLine’s tonal balance sounds pretty spot-on—neutral in the best sense of the word. While it’s certainly not as lush or richly colored as, say, an MBL component, or as surgically precise as, say, Spectral’s best designs, the SuperLine’s presentation doesn’t leave one thinking of either warmly glowing tubes or coolly cooking transistors, but instead invites the listener to lose himself in whatever the music happens to be.

It’s time for me to clarify that the sound I’m describing is with the “Full Monty” SuperLine, meaning hooked up to the SuperCap power supply. That makes this an $8500 rig—vs. $4850 when outfitted with the HiCap or the base price of $2950 if you tag-team it with another Naim component. And while none of these is an inexpensive proposition, and the SuperLine is super enough to consider owning at any level, be warned that the final choice is an almost foregone inevitability—assuming, that is, that you have a chance to compare the SuperCap with the other power-supply options.

I’ll admit that for the first month of this audition I was perfectly happy with the SuperLine/HiCap combo. While it didn’t quite float my boat when compared to a few other top-end phono preamps, it came close. But the moment the SuperCap was inserted into the system—even cold, cold, cold—the difference was obvious, and not subtle. Heifetz playing Bach’s A minor Sonata No. 2 [RCA] showcased the dramatically lower noise floor I’ve raved about, along with a much greater feeling of transparency and immediacy, and a greater degree of dynamic nuance and phrasing. In an e-mail to a friend who already owned a SuperLine/SuperCap, and who was eager to hear my findings, I wrote: “The result made listening to records so much more like eavesdropping on a moment in time, on real music-making taking place, as opposed to listening from a much greater distance in time and space. Also more richly textured, tonally complex, and ‘meaty.’ And it’s only the first five minutes!”

In an age when iPod playlists and single-song downloads are the norm, here’s another reminder that LP playback, as “long playing” implies, is about sitting down and enjoying albums—in their entirety. With Naim’s SuperLine, you’d better carve out the time to do just that, because once the needle drops you’re going to have one hell of a time leaving that chair.


Naim Superline Phonostage

Cartridge compatibility: 100mV to 500mV
Gain: 64dB
Input load options: 10k Ohms (no plug), 1k Ohm, 500 Ohms, 220 Ohms, 100 Ohms (resistive), 100pF (no plug), 1nF, 5.6nF, 10nF (capacitive)
Max output: 7.5V RMS
Inputs: One BNC, one RCA
Outputs: Naim SNAIC (w/HiCap2), Naim Burndy (w/SuperCap2)
Dimensions: 3.4" x 8.1" x 12.3"
Weight: 17.3 lbs.
Price: $2950

Naim HiCap2 Power Supply

Dimensions: 3.4" x 8.1" x 12.3"
Weight: 16.4 lbs.
Price: $1900

Naim SuperCap2 Power Supply

Dimensions:3.4" x 17" x 12.3"
Weight: 26.1 lbs.
Price: $5950 (plus $675 for the Burndy SNAIC cable)

ASL Group
8709 Castle Park Drive
Indianapolis, Indiana 46256
(317) 841-4100

Associated Equipment

TW-Acustic Raven One turntable; Tri-Planar Ultimate VII arm; Transfiguration Orpheus and Phoenix moving-coil cartridges; Artemis Labs PL-1 phonostage and LA-1 linestage; Sim Audio Moon CD-1 CD player; Chord SPM 1050 stereo power amplifier; Kharma MP150 monoblock amplifiers and Mini Exquisite loudspeakers, Tara Labs Zero interconnects, Omega speaker cables, The One power cords; Audience Adept Response Power Conditioner; Finite Elemente Spider equipment racks


 An Interview with Stephen Sells, Chief Engineer, Naim Audio

TAS: What specific design goals did you have for the SuperLine?

Stephen Sells: The goal was to design a phonostage that complemented our high-end systems. Our preamps, power amplifiers, and CD players have been continually updated and improved over the years. The SuperLine evolved using techniques from products such as the NAC552 preamplifier.

There were no limitations on size and features. The budget was okay too, so long as everything was realistic, justifiable, and not totally outrageous. For best performance unnecessary features were removed, so there’s no moving-magnet input, no variable gain, just a pure moving-coil preamplifier. I wanted to offer variable loading to get the best performance from all cartridges. Switches aren’t great for this level of performance and offer limited steps for loading. So after trying a few ideas the external DIN plug was chosen, which gives as much flexibility as you could ever want.

We also increased the voltage gain so that level balance was better when switching between CD and phono. This had become important as more low-output very high quality mc cartridges came on to the market. Noise was also a target, so we improved the signal-to-noise ratio.

TAS: What did you learn from earlier designs that you either used or discarded in the SuperLine?

Stephen Sells: The basic structure of our previous phono design is good, and the SuperLine shares the same “block diagram,” but new power supplies, cascades, and compound output devices increase the performance.

Another shared idea from previous designs is the component selection and how they are soldered to the PCB. Many SuperLine components are pre-selected to ensure that bias and equalization are spot on. Many components are also lifted away from the PCB and hand-soldered. This is also for sound quality. The PCB design has been very carefully designed to minimize inter-component capacitance and to take advantage of star-grounding, and no DC currents run in the ground where AC currents run.

During the initial design process, SPICE analysis was used with Monte Carlo analysis to ensure that the worst-case tolerance stack-up would not cause equalization errors. We achieve 0.1 dB with no problems. The equalization curve is true RIAA but with a 10Hz roll-off.

TAS: The SuperLine strikes me as unusually quiet. What were some of the things you did to achieve such low noise?

Stephen Sells: With microvolt signals, the noise performance is a guiding factor to all aspects of the design, including local power-supply regulation, amplifier circuits, component choices, microphonic and thermal. The circuit topology gives good measured S/N ratio, but it’s the microphonic and power-supply treatment that gives the perceived improvement.

The SuperLine uses two gain stages, a low noise head-amplifier and an equalization amplifier coupled together via a 75µS passive equalization stage.

The head-amplifier has a flat response, a gain of 36.7dB and is designed for extremely low noise. The common emitter input comprises four low-noise selected NPN transistors, all connected in parallel (this lowers noise), with the current and voltage optimized for low noise. This is covered with a plastic cap to lower microphonic noise; also under the cover to prevent low-frequency thermal noise is a thermal sensor, which maintains bias irrespective of temperature. Gain is set using two resistors, a selected metal-film resistor and a low-noise 0.1% wire-wound resistor, both chosen in the listening room.

The 75µS passive stage performs the high-frequency part of the RIAA equalization. This uses selected metal-film resistors and polypropylene capacitors.

The passive stage theoretically works to an infinite frequency as opposed to putting the pole in the feedback of a gain stage where it would stop as the gain approached 1x. Perfect for a controlled transient response.

It has 25 internal zero-feedback ultra-low-noise power supplies. Some are simple emitter-followers and some are constant-current sources feeding RC networks. This makes a big difference! Both have a very low time constant, which is why it takes two minutes to un-mute when turned on.

TAS: Tell us about Naim’s “floating” circuit boards?

Stephen Sells: The floating circuit board idea already features in our high-end CD players and preamplifier. It consists of a 3.4kg brass weight with six springs to form a subsonic suspension system. This is great for sound but quite expensive. There’s no dB measurement for this, just listening tests. If you tap the input capacitors or transistors you can hear it through the speakers (the input cap was subsequently directly glued down to the brass).

The unit is hand-wired to the sockets to allow the suspension to work, and the wires give great low-impedance power-supply connection.

Initially it takes a few days to run in and is fully run in after three weeks. After this time all capacitors have formed and leakage is low. Each production unit is measured and documented, then run in for 48 hours and finally listened to prior to shipping.