Thursday, May 1, 2008

Parasound Halo JC 2 line preamplifier

Hi-Fi, Audio, Amplifier Parasound Halo JC 2 line preamplifier Parasound Halo JC 2 line preamplifier Parasound Halo JC 2 line preamplifier Parasound Halo JC 2 line preamplifier Parasound Halo JC 2 line preamplifier Parasound Halo JC 2 line preamplifier Parasound Halo JC 2 line preamplifier Parasound Halo JC 2 line preamplifier Parasound Halo JC 2 line preamplifier Parasound Halo JC 2 line preamplifier

My very first review of a preamplifier, for British magazine Hi-Fi News & Record Review in May 1984, was of the Audio Research SP-10. In my opening to that review, I wrote that, "more than any other component," a preamplifier "should approximate to the late Peter Walker's 'Straight Wire with Gain.'" By this I meant that a preamplifier should not be in the business of effecting dramatic changes, and in any case, dramatic changes are not the kind that prove to be of lasting value. However, I also wrote back then that what I became increasingly aware of while using the SP-10 "was the fact that 'neutrality' is a positive virtue rather than just an absence of aberration."

I still have that review sample of the SP-10, which I purchased following the review and used for many years. Since then, I have made the acquaintance of some preamplifiers that are even more neutral than the positively neutral SP-10. But in the years since the publication of that review, I have also become increasingly aware of the paradox that while loudspeakers in general have more character than preamplifiers, I can accommodate to a loudspeaker's sonic signature far more easily than I can to a preamplifier's.

So even though I've been content with my long-term preamplifier reference, a decade-old Mark Levinson No.380S, I've kept a corner of my eye open for a possible successor. I had been impressed with Parasound's Halo JC 1 monoblock, which I had measured for Michael Fremer's review in the February 2003 Stereophile (Vol.26 No.2). And I'd had enormous respect for the Halo JC 1's designer, John Curl, ever since the early 1990s, when I'd used and enjoyed one of his Vendetta SCP-2 phono preamplifiers. So when Parasound prexy Richard Schram e-mailed me, after last year's Home Entertainment Show, to ask if he could drop round with a sample of his new, Curl-designed Halo JC 2 line preamplifier, he didn't need to twist my arm too much.

The Halo JC 2

Costing a not-unreasonable $4000, the Halo JC 2 is manufactured, like the JC 1, in Taiwan. But its design, circuit layout, and parts choice are unabashedly American. John Curl began designing the JC 2 while working on the JC 1, and optimization of the design was performed by him, with the late Bob Crump choosing the parts and Carl Thompson laying out the boards. "Designed by CTC Builders John Curl, Carl Thompson & Bob Crump," it states at the top of the rear panel—a nice touch.

Styled to match the JC 1 and finished in the same brushed, natural aluminum, the JC 2 is a smart if rather bulky-looking component. The front panel is dominated by a rectangular red logo at the top center that glows bright red when the amp is operated, and by a volume knob at the far right. An inset panel at the bottom contains an aluminum pushbutton at each end, these softly backlit in blue; between them runs a row of six blue LEDs, to indicate which source has been selected. The source-selector button is the one on the right; pushing it repeatedly scrolls through the inputs from left to right. The button on the left wakes the preamp from Standby. A red LED flashes when the preamp is muted with the remote. There is no balance control as such, but two small knobs adjust the two channel gains by up to –10dB.

The rear panel is dominated by the two rows of input and output jacks, one row for each channel. There are six pairs of unbalanced inputs, two of which can be switched to balanced mode. As well as a pair of fixed-level Record Out RCAs, there are inverting and non-inverting main unbalanced outputs on RCAs and a pair of balanced outputs on XLRs, these wired with pin 2 hot. The gold-plated RCA jacks are all sourced from Vampire, the XLRs from Neutrik.

Internally, vertical 3/8"-thick aluminum panels separate the chassis into three shielded regions. On the left is the inductor-smoothed power supply, based on an R-core transformer and fast, soft-recovery bridge rectifiers and diodes. There is a separate supply for the relay coils, triggers, LEDs, and control circuitry, this carried on a vertical board behind the front panel.

The audio circuitry, shielded from the power supply and control sections, is carried on a separate board for each channel, and is based on hand-matched complementary FETs, a feature of John Curl's designs for a quarter-century now. The circuit is direct-coupled, with no capacitors in the signal path, and with DC offset controlled by a servo circuit. Following the short signal path, the input jacks feed a relay driven by the input-select switch. A four-gang, motor-driven potentiometer adjusts volume and polarity inversion of the output signal is performed with gold-on-silver–contact relays.

The Halo JC 2's construction is to a high standard. The only disappointment was its rather flimsy and resonant top plate and its plastic remote.


I have never been one to believe in long break-in periods—or even break-in, period, for anything other than loudspeakers. But to my surprise, the Halo JC 2 definitely improved in sound quality during the first week it was plugged in. Not that this Parasound will ever be mistaken for a mellow-balanced component, but it took a few days of being left on for the initial brashness of its mid-treble to slowly recede until it was properly balanced with the midrange and top octave. Then I began to appreciate how much it did right and how little it did wrong.

Take soundstaging. Many audiophiles dismiss the ability of a component to render a believable soundstage as being a superficial indicator of its quality. But ever since I first heard a system that could paint a stable, accurate, solid picture of the recorded event, I have placed a high value on this aspect of sound reproduction—as long as it is not achieved at the expense of similarly great performance elsewhere.

Kal Rubinson recently gave me a copy of Marianne Thorsen's performance of the Mozart Violin Concertos 3–5, with Oyvind Grimse conducting the Trondheime Solistene (SACD, 2L 2L38SACD), which he listed as one of his "Records To Die For" in the February issue. Recorded in a small church, the sound is quite close, but the Halo JC 2's ability to resolve spatial information allowed me to detect the subtle dome of ambience surrounding the musicians, especially in Thorsen's unaccompanied cadenza in the Adagio of Concerto 3. The balance was somewhat light in weight, but there was enough lower-midrange energy to flesh out the delicate scoring.

Compared with my long-term reference preamp, the Mark Levinson No.380S—also a soundstaging champ—the JC 2's lighter balance allowed more of the recorded detail to be resolved without thrusting it forward at me. On the 96kHz-sampled version of Neil Young's Chrome Dreams II (DVD/CD twofer package, Reprise 340220-2), the Parasound's superb definition on the drums and bass guitar was highlighted by the hints of the recording studio acoustic illuminated by the drums. The hushed, luminous backwash of strings that presages the entrance of Hilary Hahn's solo violin in Vaughan Williams' The Lark Ascending (SACD, Deutsche Grammophon 28947-48732-6) was spread from far left to far right, yet the central image of Hahn's violin remained small and vulnerable, stable, and free from bloat.

During the review period, I was working on the remastering of Stereophile's latest CD release, a reissue of Robert Silverman performing the two Rachmaninoff piano sonatas (STPH019-2). When I played the 16-bit WAV master files from my Slim Devices Transporter, the transparency of the JC 2 allowed me to hear slight low-level glitches that I needed to clean up in the mastering. But to my surprise, I heard a very slight improvement in the sound's tangibility when my WiFi network was down for a while for updating and I used a hardwired Ethernet connection from my Mac mini to the Transporter. But I shall say no more—that way lies madness.

The Halo JC 2's ability to reproduce space was even evident on monophonic recordings. I bought the reissue of Miles in Berlin, the first live recording of the great 1960s Miles Davis quintet (CD, Columbia/Legacy 2796-93594-2), back when it was released in 2005. But I hadn't played it much, both because it was mono and because I found off-putting the breakneck tempo with which bass player Ron Carter begins "So What." But giving the disc a second chance one night when I had the Magico V3 loudspeakers set up with the JC 2 and JC 1s, I was surprised to be able to hear deep into the mono image, the instruments sufficiently separated in space that I could now start to make sense of the music-making during this tune, and begin to comprehend the interplay of Carter, drummer Tony Williams, and pianist Herbie Hancock. In "Stella by Starlight," I could hear Miles backing away from the mike during his solo to emphasize the dynamics, and tenor-sax player Wayne Shorter approaching the mike to take his solo in the same song.

Yes, the Parasound could do space. But the first aspect of the Halo JC 2 that I noticed was the definition and the weight of its low frequencies. It grabbed my attention when I was finishing up my review of the KEF Reference 207/2 loudspeaker (February 2008), and the battery of my iPod had given up just as I was leaving the office for the night. "Borrow mine," said Stephen Mejias—a generous gesture, considering that listening to someone else's iPod is like listening into his soul.

Suitable amplifiers

I did much of my auditioning of the Halo JC 2 with the Mark Levinson No.33H monoblocks I purchased 10 years ago. But I also had on hand the Musical Fidelity 550k Superchargers that Mikey Fremer reviewed last September, and the Boulder 860 stereo amplifier that Fred Kaplan reviewed in December. And Parasound's Richard Schram had sent along a pair of Halo JC 1 monoblocks for me to use with the JC 2.

Depending on the speakers, the JC 2's sonic personality worked better with the softer, warmer amplifiers, such as the Boulder and the Levinson monoblocks. When all things are considered, transparency is a two-edged sword! Like the Halo JC 2, the Musical Fidelity Superchargers have tight, powerful low frequencies; the pairing worked well with the big-hearted, ported KEF R207/2s. But with the sealed-box Magico V3s, the combination of Parasound and Superchargers was just too lean, even though the bass definition was to die for. These speakers worked best with the Mark Levinson No.380S and No.33Hs. By contrast, the Levinsons sounded bloated and somewhat slow with the KEFs. The best overall balance I achieved with the Sonus Faber Cremona Elipsa speakers was with the JC 2 driving the Boulder 860. Yes, the lows still lacked ultimate definition with the Boulder, but this was compensated for by the huge soundstage and silky highs.

The Halo JC 1

With Parasound's own Halo JC 1 monos ($7000/pair), once they'd broken in, I was reminded of Mikey's comment in his February 2003 review: "The JC 1's ability to separate the vocal from the subtle artificial reverb, both in time and layered behind in space, was a revelation. And it was done without spotlighting or added brightness. The overall lack of smear helped create an impressively coherent, transparent, and detailed soundstage, with the kind of air and reverberant presentation I usually associate with tubes." The JC 2 took this ability of the JC 1s further along the road to the system opening a clean, transparent, rectangular window on the original acoustic of the recording.

Although Live at Merkin Hall (CD, Stereophile STPH018-2), my ultimate recorded statement of Bob Reina's free-jazz ensemble Attention Screen, is multimiked, over the past 18 months I have also recorded the band with just two mikes in a variety of New York jazz clubs. Though the musical balance is rarely well served, there is something magical about the sound of recordings made with such a purist technique. Listening to the original 24-bit/88.2kHz files of the club recordings with the Parasound Halo preamp and power amps driving the Magico V3 speakers, there was an almost holographic sense of being at the original event, so clearly could the positions of the musicians be discerned within the space of each club—whether the deep recess of the Knitting Factory's Tap Room, or the drier but paradoxically more supportive acoustic of the back room at Otto's Shrunken Head. Going back to the Merkin Hall concert, and again playing the 24/88.2 masters on the same system, I wasn't displeased with the mix. The individual sounds of the instruments were better served than with the purist recordings, and the hall's rich ambience was coherent. But the Parasound pairing revealed how close I was sailing to the edge with the multichannel mix, how close I was to the seams in the illusion starting to show.

This ability to let the listener hear deep into the recesses of a recording's genesis was not restricted to purist, private-label recordings. I recently picked up the reissue of a recording I played to death when it was first released in 1982, La Folia de la Spagna, from Atrium Musicae de Madrid under Gregorio Paniagua (CD, Harmonia Mundi HMA1951050). As well as the usual settings of this baroque-era "hit song" for traditional broken consorts of various kinds, there are such joys as a version of the tune "performed" on control-line model airplanes accompanied by tabla, and even a clarinet, punctuated by car horn, unable to resist wandering off into Pink Panther territory. There are starter-pistol shots and whipcracks to test a system's dynamics, and such subtleties of soundstaging and acoustic as a close-miked thumb piano, a distantly miked hammered dulcimer, an outdoors ensemble of two-stroke leaf blowers, and a drive-by of what sounds like an antique Land Rover, complete with honking horn—in all, a sonic smorgasbord that tests to its limits a system's appetite for punishment. The combination of Parasound preamp and power amps unveiled the depths of the soundstage, maximally differentiated every quirky tone color, and dispatched the dynamics without breaking a sweat. And set to run with its maximum output-stage bias current, the Halo JC 1s kept my listening room nicely warm through the usual holiday cold snap!

Summing up

I had a quibble with the Halo JC 2's plastic remote, which, with its concave bottom and the weight of the batteries all at one end, proved adept at falling off whatever I placed it on. The remote's Volume Up and Down buttons were also a bit trigger-happy; I often over- or undershot the level I wanted, until I became accustomed to the necessary technique: a succession of quick jabs rather than a prolonged press.

But when, in a review of a high-end component, a writer is reduced to criticizing the remote control, for goodness' sake, it's a sign that everything else is pretty much beyond criticism. No, you don't want to pair the Halo JC 2 with lean-sounding power amplifiers or loudspeakers, but otherwise, Sam Tellig called it in his column in the December 2007 issue (p.24–27): "The JC 2 allows music to emerge intact—with body, bloom, and dynamics, with definition and detail—from an utterly silent background....[T]he JC 2 excels at the reproduction of space." Nothing in my auditioning persuaded me that the inestimable Mr. T. had gotten it wrong. In fact, he—and Parasound and John Curl—got it very right. And at a price that will be within the reach of real-world audiophiles.

Sidebar 1: Specifications

Description: Remote-controlled, solid-state preamplifier with switchable absolute polarity, rear-panel IR repeater input and loop out jacks, four 12V trigger output jacks, and two-way RS-232 serial port. Inputs: 6 unbalanced (RCA), 2 usable in balanced mode (XLR pin 2 hot). Outputs (1 pair each): balanced XLR (main); unbalanced RCA (main); inverted unbalanced (main); normal-polarity, fixed-output, unbalanced (tape). Left/right gain-control range: –10dB. Frequency response: 5Hz–100kHz, +0/–3dB. Maximum gain: 14dB. Maximum output: 8V. Input sensitivity: 200mV for 1V output. Distortion: <0.003% THD at 100Hz, <0.005% THD at 20kHz, <0.003% IMD. Signal/noise: >116dB, input shorted, IHF A-weighted; >104dB, input shorted, unweighted. Channel separation: >100dB at 10kHz, >90dB at 20kHz. Input impedance: 30k ohms unbalanced, 30k ohms per phase balanced. Output impedance: <60 ohms unbalanced, <60 ohms per phase balanced. Power consumption: 25W standby, 30W in operation. Optional accessory: HRA 3 rack-mount handles (can be purchased separately).

Dimensions: 17 1/4" W (437mm) by 5 7/8" (150mm) H by 16" (406mm) D. Weight: 24 lbs (11kg).

Serial Number Of Unit Reviewed: 689076914765. Price: $4000. Approximate number of dealers: 20. Warranty: 10 years parts, 5 years labor (US, Canada).

Manufacturer: Parasound Products, Inc., 950 Battery St., San Francisco, CA 94111. Tel: (415) 397-7100. Fax: (415) 397-0144.

Related Links...