- Category: Full-Length Equipment Reviews
- Created on Friday, 15 July 2011 01:00
- Written by Peter Roth
One name that stands tall in solid-state circuit design is John Curl. From proving, with the release of the Mark Levinson JC-2 preamplifier in 1975, that transistors and high-quality sound were not mutually exclusive, Curl has made a series of formidable achievements. Perhaps most revered is the Vendetta Research SCP-2 phono preamplifier, which, despite total production of only some 200 units from the late 1980s to the early 1990s, has inspired a cult-like following.
The year 2011 heralds the release of two new phono preamplifiers designed by Curl: the two-chassis, everything-but-the-kitchen-sink Orion from Constellation Audio ($40,000 USD); and Parasound’s Halo JC 3, a no-frills alternative with a no-frills price ($2350). Curl commenced working with Parasound in 1989, and his designs for the company have generated accolades for high performance and high value ever since. Two products at the very top of Parasound’s premium Halo line even wear Curl's initials -- the JC 1 monoblock power amplifier and JC 2 stereo line preamplifier, components which make a run at reference-level performance while keeping at least one foot on the value side of the fence. That well-established pair is now joined by the Halo JC 3. My task: Substantiate or disprove this phono preamplifier’s position as a worthy descendant to the Vendetta SCP-2, and certify whether or not it deserves to bear the initials of its illustrious designer.
She wears blue velvet
It’s always interesting to see how a manufacturer protects its wares for shipping around the world. The really expensive gear tends to arrive in a crate or flight case. Standard consumer-electronic fare makes do with a box of single-ply cardboard, with more attention paid to cosmetics than to structural integrity. Most high-end companies, however, use the tried-and-true system of two boxes of single-ply cardboard. I regularly see one of two versions of this approach: the floater (i.e., one box floating within a larger box, separated by some type of cushion or Styrofoam); or the double wall (i.e., two boxes nested to make a single, extra-strong, double-walled box). Parasound uses this second method, combining two robust, conjoined cardboard boxes with a thick interior layer of polystyrene to encapsulate the JC 3. The component is double-bagged as well: The presentation pouch of blue velvet is a classy touch, and inside that is a thick poly bag. So nestled, the JC 3 should be safeguarded from all but the most violent drop, shock, perforation, or scratch. An interior cutout for the separately sheathed accessories completes the packaging -- purposeful, with a touch of class. The very clear and concise instruction manual exudes professionalism.
The blue-velvet theme is continued on the JC 3’s Spartan front plate, which is adorned by only two pushbuttons, one toward either end of a narrow groove that runs nearly the entire width of the panel, just above its bottom edge. Both buttons are backlit blue in normal operation: On/Standby on the left, Stereo/Mono on the right (when Mono mode is activated, the backlight changes to amber). There is no display, but the Parasound logo at top center glows a faint red to indicate that the rear AC power toggle is on, and brighter when the JC 3 is switched from Standby to On.
The JC 3’s austere outward appearance is continued on the aluminum rear panel, which is in three sections. At the far right are the IEC inlet (a heavy-duty power cord is supplied); toggle switches for on/off and AC Polarity Invert/Normal (which can reduce hum in many systems); and a switch enabling the JC 3 to be turned on automatically when connected to a preamp with 12V triggers (there are adjacent In and Loop jacks). At the panel’s left and center are two recesses (one per channel), each about 4”W x 1.5”H and housing a cluster of connections: from left to right, a single-ended RCA input, a three-position toggle for setting gain and loading (47k ohms MC, MM, and 100 ohms MC), and unbalanced and balanced outputs. Between these recesses is a lone, gold-plated chassis ground terminal.
The brushed-aluminum case is liveried in two-toned silver -- two slightly darker endcaps (each about 1.5”W) contrast smartly with the rest of the faceplate. There are no color options. Rather large at 17.25"W x 4.125"H x 13.75"D, and weighing 18 pounds, this heavyweight seems ready to take on all challengers -- and, true to Parasound’s professional lineage, the 2u Halo JC 3 can be mounted in a rack with the optional HRA2 kit.
The inside story
While the Halo JC 3 may be seen as an heir to the Vendetta SCP-2, that earlier effort was a handmade, built-to-order, four-box design (with separate enclosures for each channel and its power supply), utilizing completely discrete circuitry. Built in Taiwan in batches of 100 or so, the JC 3 is more appropriately identified by Parasound as a direct descendant of the essential design elements of its Halo JC 1 monoblock and JC 2 preamplifier. Applied to all is John Curl’s consistent approach to circuit design, which he summarized as follows:
My direction in circuit design is to make direct-coupled, class-A, push-pull complementary circuitry, that is low noise on the input and with low-order distortion only [as opposed to higher-order harmonic distortion] at the output. . . . Audio design is a progression of learning what works, and using it, rather than doggedly sticking to some pre-programmed idea of what is important and not. Also, it is not an arbitrary assembly of different parts that go in and out of favor. Like tubes this year, solid-state last year, and a hybrid design of both next year.
Only solid-state devices are employed in the JC 3, primarily integrated circuits (ICs). True to Curl’s philosophy, the circuit is a truly balanced, dual-differential design, with vanishingly low noise being of paramount importance. Global and local feedback loops ensure exceptional linearity and eliminate all but the lowest measurable distortions. The design avoids the use of coupling capacitors because, according to Curl, any capacitors in the signal path -- even exotic, high-priced ones -- impose on the sound their own character. Rather, the circuit is DC servo-coupled. RIAA equalization is passive, using parts identical to those found in the Vendetta SCP-2, and takes place between the first and second stages of amplification. Circuit gain is 68dB for moving-coil cartridges (which can be loaded with 100 or 47k ohms), and 47dB for moving-magnet cartridges (47k ohms only). By limiting the choices of loading and gain, Curl has obeyed the mantra of “Keep it simple, stupid” and maximized cost-effective performance.
While it’s easy to focus on the designer’s legendary status, Curl himself is quick to sing the praises of longtime collaborator Carl Thompson, whose artistry in circuit-board layout Curl considers an element essential to achieving the best sound. The compact Curl-Thompson audio circuits, which require only a few square inches of circuit-board, reside in two independent phono-stage modules, one per channel, each housed in a subenclosure of extruded aluminum designed to protect the sensitive circuitry within from any potential channel crosstalk. The design is truly dual-mono -- the two modules are linked, via a relay-based umbilical, only when the user chooses to merge them for mono output. Further, these subenclosures constitute the second “box” in the chassis’ dual-box system of isolation, which strives to prevent any extraneous RFI or EMI from contaminating the musical signal.
The dual-mono design of the Halo JC 3 is carried through to the power supply. Laid out on a single circuit board in mirror-image fashion on either side of the center-located rectifier, the power supply board is fed by an R-core transformer. Each channel’s power regulation is autonomous. As noted above, compartmentalization and the electrical segregation of sensitive audio circuits have been given the utmost attention -- to scrutinize the internal arrangement of the JC 3 is tantamount to auditing a master class in form following function. Essentially, three zones are created by carbon-steel partitions within the substantial chassis, which is otherwise made of aluminum. The first zone -- the left, rear portion of the JC 3’s interior -- contains the IEC power input and onboard power conditioner. Residing in the second zone, which comprises the interior’s forward third, are the transformer (on the left, linked to the power-input chamber), the dual-mono power supply (occupying most of the space), and the control software. The third zone contains the two single-channel phono-stage subenclosures detailed above. All three areas are large enough to provide elbow room for their resident subassemblies, thus creating buffer zones of further isolation.
From talking with Parasound president Richard Schram at the 2011 Consumer Electronics Show, subsequent conversations with John Curl, and the intelligent design evident from my close examination of the Halo JC 3, I had high expectations despite one apprehension. I have often been disappointed when high-fidelity aspirations are coupled with ICs and global feedback. Nonetheless, I always try to remember that it is implementation, not dogma, that makes or breaks a product’s sound. It’s obvious that tremendous amounts of thought and expertise have been expended in the development and manufacture of the Halo JC 3. Was it a hit or a miss?
It is alive!
While the Halo JC 3 is anything but a Frankenstein’s monster (it looks just great), the phrase that came to mind when I dropped the tonearm the first time was “It is alive!” Bam -- the JC 3 was ready to rock with a standout “jump” factor. Part of that initial reaction was undoubtedly attributable to the high gain of the Halo’s MC stage -- 68dB is plenty enough to handle almost any cartridge, even those with output levels below 0.1mV. Nevertheless, even after I’d recalibrated the volume with my trusty RadioShack analog sound-pressure-level meter, it was clear that the JC 3 lacked for nothing in dynamics.
Richard Schram recommended several hundred hours of break-in, but suggested that most of the expected improvement will be on hand after only 50 hours of play. Accordingly, I spent the first few weeks just logging hours and enjoying records. During that time I was reminded of how convenient it can be to have a solid-state phono stage constantly on and ready to go. Whenever I found an extra five or ten minutes, I could sneak in an impromptu track or two.
One track I returned to again and again while getting a handle on the JC 3’s performance was “Cry Me a River,” from Julie London’s seminal Julie Is Her Name, Vol. 1 (45rpm, Liberty/Boxstar 3006). This is a mono recording, and the musicians lined up dead center, as they should when a cartridge’s azimuth has been properly set (and confirmed by Fozgometer) in my Spiral Groove Centroid tonearm. But even with this mono recording, a real sense of space and layered depth was revealed through the JC 3. Further, the presence and sultry sensuality of London’s phrasing were never less than palpable, setting the mood and proving anything but plebeian.
After about 100 hours of play, it became clear that the JC 3’s fortes were pace, pizzazz, and punch. This phono stage was a superb conduit for rock and up-tempo jazz. The title track of A Night in Tunisia, by Art Blakey & the Jazz Messengers (45rpm, Blue Note/Music Matters MMBST-84049), exemplified the Halo’s strengths. A real barnburner, this breakneck arrangement can play havoc with lesser equipment, and turn artistry into cacophony. Not so the JC 3, through which the music’s controlled velocity never collapsed or became confused. The track’s tempo played to the Halo’s strengths, as did the incredible energy evoked by the ensemble in general, and specifically by the power of Blakey’s percussive pyrotechnics.
Without question, the JC 3 showed itself to be an accomplished and deserving participant in my analog front end. But how would it stack up against my longtime reference phono preamplifier, the tubed Aesthetix Rhea Signature ($7000) -- or its predecessor, the solid-state Ayre Acoustics P-5xe ($2500)?
Compare and contrast
As mentioned above, the Halo JC 3 has only three choices of cartridge gain and loading, those chosen as the essential settings necessary to accommodate the vast majority of cartridges. For MCs, changing the loading from 100 ohms to a wide-open 47k ohms is only a flip of a switch away. By contrast, the Ayre P-5xe and the Aesthetix Rhea Signature offer dozens of combinations of load and gain, the better to fine-tune to the user’s taste and the particular characteristics/interactions of cartridge, cable, and phono stage. The Aesthetix even offers full remote control, to make a snap of dialing it in from the listening seat, not to mention three inputs, multiple outputs, and a built-in cartridge demagnetizer (although so many features should be expected at three times the Halo’s price).
One of those features is the Rhea’s ability to compete with solid-state designs in producing a black, low-noise background. Compete it may, but it couldn’t match the absolute silence of the JC 3 (or the Ayre P-5xe) at rest. The difference between such true silence and the noise floor inherent to spinning vinyl was almost startling when the needle dropped into the lead-in groove. The Rhea Signature has a very dynamic, toe-tapping sound, but even with an equivalent gain setting of 68dB and run wide open (47k ohms loading), it couldn’t quite match the Parasound’s sense of immediacy. By contrast, the Ayre offered a more relaxed, mellow sound. All three phono stages maintained a secure grip on the proceedings, maintaining composure regardless of source material.
The JC 3 matched the Rhea’s ability to project a rock-solid soundstage from left to right, but where the Rhea really shone was in front-to-back dimensionality. The tubed phono preamp fleshed out instruments with senses of heft, depth, and height; the solid-state JC 3 left them rather more two-dimensional. What was true for particular instruments in this regard was even more pronounced for the soundfield as a whole -- there was simply more there there through the Aesthetix. While the Ayre P-5xe couldn’t quite match such pinpoint, locked’n’loaded lateral staging, it produced a depth of both instrument and stage that was fuller and more substantial than its solid-state compatriot, though still several shades paler than what the Rhea Signature delivers.
The Rhea also produces a musical flow that is more like a live performance -- natural and organic -- than either solid-state contender could capture. While some may ascribe these differences to a euphonic bloom or editorializing due to the use of tubes, I don’t agree. Tubes, especially the triodes used by such high-end stalwarts as Aesthetix and Audio Research, are inherently linear devices that permit the design of simpler circuits with fewer devices in the signal path, and less reliance on feedback loops. This was most evident with classical music. In Mussorgsky’s Night on Bare Mountain, with René Leibowitz conducting the Royal Philharmonic Orchestra on The Power of the Orchestra (45rpm, RCA Living Stereo/Analogue Productions AAPC 2659-45), the dynamic horsepower of the orchestra was evident via both the Halo and the Aesthetix, but the scope, scale, and substance of the massed players was better served by the dynamic torque exerted by the Rhea.
At the end of the day, the Halo JC 3 and Ayre P-5xe are both excellent designs and high-value propositions. Nevertheless, each has a distinct sound that will best serve a different sort of master. I would short-list both for audition, and handicap the JC 3 for those who favor up-tempo jazz and rock, while giving the P-5xe the nod for more classical sensibilities. In temperament and talent, the Parasound more closely parallels the Aesthetix, which clearly distinguishes itself as the most accomplished of the three. In any event, that the one-third-the-price Halo JC 3 couldn’t quite match the heft and body of the Rhea Signature shouldn’t surprise. What is somewhat shocking is just how close John Curl’s latest design comes to doing so. For a grand less than the cost of the Rhea Signature alone, an animated and engaging analog front-end could be assembled. I believe that the Halo JC 3, a VPI Classic turntable, and a Lyra Delos MC cartridge would be a choice combination that would put to shame most digital alternatives, regardless of cost.
John Curl and Parasound have done it again -- the Halo JC 3 is a worthy sibling to the other John Curl signature components of Parasound’s Halo line. I commend Parasound and Curl for transporting much of the legendary sonic achievements of the Vendetta phono stage across more than two decades and into such an accessible and cost-effective product. The Halo JC 3, with its absurdly reasonable price of $2350, sets the performance/price ratio ridiculously high. Does it provide unlimited customization, or that nth degree of three-dimensionality and natural flow achieved by the best tubed circuits? Perhaps not, but be prepared to spend many multiples of its retail price to achieve even marginal increases in sound from solid-state or tubed alternatives.
. . . Peter Roth
- Speakers -- Vandersteen 5A
- Analog source -- Spiral Groove SG-2 turntable, Centroid tonearm, Lyra Kleos MC cartridge; Aesthetix Rhea Signature, Ayre Acoustics P-5xe phono stages
- Digital sources -- Ayre Acoustics DX-5 Universal A/V Engine; Apple MacBook Pro; Amarra 2.2; AudioQuest 0.75m Diamond USB cable
- Preamplifiers -- Ayre Acoustics KX-R, Audio Research Reference 5
- Power amplifiers -- Ayre Acoustics MX-R monoblocks
- Interconnects -- AudioQuest Wild Blue Yonder
- Speaker cables -- AudioQuest WEL
- Power cables and conditioners -- AudioQuest NRG-100 power cables; Ayre L-5xe, Furman IT-Reference 20i power conditioners
- Support platforms -- Harmonic Resolution Systems MXR rack with M3X shelves
Parasound Halo JC 3 Phono Stage
Price: $2350 USD.
Warranty: Five years parts and labor.
Parasound Products, Inc.
2250 McKinnon Avenue
San Francisco, CA 94124
Phone: (415) 397-7100
Fax: (415) 397-0144