Nagra BPS Battery-Powered Phonostage (TAS 198)

Equipment report
Nagra Battery-Powered Phonostage
Nagra BPS Battery-Powered Phonostage (TAS 198)

In his excellent biography of the Swiss-born sculptor and painter Alberto Giacometti, James Lord relates a charming story from a difficult time. It was 1939, the Germans had just invaded Czechoslovakia, and the Swiss government decided to hold a National Exhibition to reaffirm “traditional values” (whatever those were). Giacometti, whose slender figurines were at the time becoming increasingly miniaturized, was invited to exhibit a major sculpture in the central courtyard of the textile pavilion. When greeted by the guy in charge of installing the artwork, who had a truck ready to haul it from the train station, Giacometti reportedly replied, “There’s no need for the truck. I have the statue with me.” At which point he pulled a large matchbox from his coat pocket and produced a tiny plaster statuette no more than two inches high. To say that those in charge of this patriotic event were not amused would be putting it mildly.

I had a similar—though not unpleasant—surprise recently, when my UPS driver delivered a somewhat different Swiss-made object to my doorstep. The carton I signed for was small and lightweight, and I assumed it contained a book I’d ordered on-line. Without even looking at the shipping label I grabbed a utility knife and sliced through the packing tape. Of course, I’ve already spoiled the punch line, because what I found inside was no book but Nagra’s latest phonostage, the battery-powered BPS.

While Nagra’s gear is typically modestly sized, at a miniscule 4.25" x 1" x 6.25", and a featherweight 16.9 ounces, the BPS takes modest size to a Giacometti-esque level. Moreover, the company’s superbly engineered and built products usually command very high prices. So it’s refreshing to report that the BPS is priced at a relatively affordable $2399.

Interestingly, the BPS (which stands for Bipolar Phono Stage) is only the second standalone phono preamp from Nagra. It comes on the heels of the VPS (Valve Phono Stage, $5995), which was released in 2008. Indeed, Nagra’s development report for the BPS says it was based on the circuit of the VPS—itself derived from the firm’s $12,795 PL-P preamp—but revised and adapted for transistorized circuitry. Nagra’s work with low-level signals in microphone preamps and digital recorders led the company’s engineers to focus on a unit that would be very compact in size, utilize the shortest possible signal paths with no internally wired connections (resulting, Nagra says, in strong immunity to RFI), use highly efficient circuits that could operate from a simple very-low-noise power supply fed by a single 9V battery, have sufficient gain for low-output moving coils, and employ the modular impedance-loading circuit found in the VPS and PL-P.

Keeping with Nagra’s professional vibe, the top plate of the anodized, brushed aluminum chassis is decorated with screen prints of diagrams for the main circuit, power supply, phono load, and in/out connections. Given my lack of technical chops, I could only decipher the latter. Otherwise, these squiggly circuit renderings brought to mind another Swiss artist, Paul Klee, whose playful drawings I recently viewed at San Francisco’s Museum of Modern Art.

The 9V battery nests inside its own tiny compartment, and accessing the BPS’s interior to insert that battery, change load values and gain, and so on reveals a splendidly built, miniature, double-sided, gold-plated circuit board, complete with a pair of tiny Nagra-made transformers for boosting the output of moving-coil cartridges. As mentioned, all connections are wired directly to the board; carefully sorted and matched bipolar transistors provide amplification. And should you encounter hum or RFI, as I did, living not far from our city’s main broadcast tower, you may switch the BPS from its standard unbalanced mode to balanced via internal jumpers, which works like a charm to eliminate noise.

Aside from the RCA inputs and outputs and grounding lug round back, the only control on the BPS is a three-way toggle on the front plate, which serves as an On/Off switch and battery tester (a glowing bright red LED indicates a healthy battery).

Rather than your standard cardboard box or fancy Bordeaux-style wooden crate, the BPS comes packaged in a small plastic-anvil-like case, with protective foam inserts carved out for the phonostage, two Allen keys, a 9V battery, and a set of six mc load modules (three resistive, three capacitive).

Because battery life is estimated at 100 hours and also because, like most solid-state circuits, the BPS will sound its best when left continuously on, Nagra has also placed a socket on the unit’s rear that accepts a 7–10V wall-wart-type power supply with a direct current of 10 milliamperes. While the power supply is not included, you can pick one up at your local Radio Shack. The twelve bucks or so spent will not only easily pay for itself in spared battery life (the battery engages or disengages when the supply is plugged in and out), it will also ensure that your BPS is always at its best, since it can sound a little bright and edgy before it is warmed up. If you operate the unit by battery only, switching it on and off, that’s the sound you’re likely to get all the time (unless you wish to burn though a pile of 9-volts). Using the wall-wart, leaving the BPS in the On position, and simply disconnecting the wall-wart’s plug before a listening session to let the battery take over gives you a far cleaner, warmer, smoother, more dynamic, and much more musical sound.

Come to think of it, it’s a winning combination of the pristine and the warm that defines the BPS’s sonic signature. Now, “pristine” and “warm” may sound at odds with each other, but they aren’t, really, as I’ll try to describe.

By pristine I mean that the BPS is accurate—transparent to the source. Record after record, track after track, the individual strengths, weaknesses, beauty marks, and (slightly airbrushed) flaws of each LP make their ways through the BPS in the most relaxed, straightforward ways. If the Nagra imposes any sonic signature of its own, and of course it does, it’s that, while every record sounds wholly like itself, it also sounds exquisitely composed, beautiful, and ultimately musical—and that’s what I mean by warm.

Pulling out an old chestnut, Ella Fitzgerald’s Clap Hands, Here Comes Charlie! [Verve], and putting on the track “Good Morning Heartache” readily demonstrate my point. One of Fitzgerald’s most beautiful and emotionally infused ballads, the tune begins with descending and then ascending piano, bass, and guitar lines, with a delicately tapped triangle as percussive accent. Through the BPS, the music hangs in the air with a rare sense of immediacy. All instruments are richly toned and textured, superbly focused without sounding artificially outlined. And when Fitzgerald begins to sing, she seems so present, in voice and spirit, that the heartbreak she sings about has the impact of listening to a friend in despair, not simply a distant voice on a 50-year-old slab of vinyl.

This transparency also beautifully serves a small-scale orchestral piece such as Luigi Nono’s Polifonica-Monodia-Ritmica (1951), played by the English Chamber Orchestra under Bruno Maderna [Mainstream Records]. This work of subtly shifting rhythms and dynamics begins with a quiet dialog between various wind instruments, against a gently shimmering cymbal. The BPS really brought instruments and ensemble to life—its low noise floor, pinpoint focus, and superb microdynamic resolution emphasizing the rhythmic and emotional tension Nono builds up between the players. And because the ensemble emerges from deep silence, the instruments sound remarkably “there,” flickering in and out like stars in a country-clear night sky.

While the BPS’s beauty, low-level dynamic precision, and transparency are exceptionally fine for smaller-scale stuff, the unit lacks the ultimate power and bottom-end heft many find desirable for, say, a Mahler symphony or other pull-out-the-stops orchestral pieces, or for power rock. Playing the Classic Records reissue of The Who’s Live at Leeds, I was impressed by the BPS’s ability to peer into the musical event, but missed the final degrees of bottom-end weight I like to hear from Keith Moon’s pummeled double-kick-drum kit, the ox-like chug of John Entwistle’s bass, and the windmilled chords of Townshend’s electric guitar. These, and the sheer drive of the band, weren’t exactly “polite,” but they were perhaps a bit too refined.            

In this regard the BPS is not alone. To various degrees this reticence has long been observed with battery-powered gear. And given that the BPS draws power from but a single 9-volt, a noticeable lack of sheer power was to be expected.

Whether this is a deal-breaker or not will depend entirely on where your musical preferences fall. If I lived on a steady diet of Nine Inch Nails, Neil Young with Crazy Horse, and Ring cycles, I might think twice. If, on the other hand, I spent most hours spinning jazz, vocals, moderately scaled rock and classical—solo violin and piano are likewise a knockout through the BPS—then I would heartily recommend Nagra’s BPS as one of the most satisfying phonostages I’ve heard. The fact that it’s practically a pocket edition audio component, and also a most reasonably priced one, only sweetens the deal.


Nagra BPS Battery-Powered Phonostage

Gain: 62dB (mc), 51dB (mm)
Supplied load options: 100 ohms, 220 ohms, 330 ohms, 100pF, 220pF, 470pF
Battery type: 9V
Output: 2V
Inputs/outputs: RCA
Dimensions: 4.25" x 1" x 6.25"
Weight: 16.9 ounces
Price: $2399

Nagra USA
180 N. Belvedere Drive,
Unit 5A

Gallatin, TN 37066
(615) 451-4168

Tempo Sales & Marketing
Waltham, Massachusetts
(617) 314-9296

Associated Equipment

TW-Acustic Raven One turntable; Tri-Planar Ultimate VII arm; Transfiguration Orpheus moving-coil cartridge; Artemis Labs PL-1 phonostage and LA-1 linestage; Kharma MP150 monoblock amplifiers and Mini Exquisite loudspeakers, Tara Labs Zero interconnects, Omega speaker cables, The One power cords, and BP-10 Power Screen; Finite Elemente Spider equipment racks