Parasound Halo JC 1
High value at a low(ish)
Review By Wayne Donnelly
here to e-mail reviewer.
reader may be somewhat surprised at finding a Parasound product reviewed
in Superior Audio. This San Francisco-based company has for years offered
well made, good-value products that compete principally with other
value-priced marques such as Adcom, B&K and Rotel. Since 1989
Parasound has retained the services of John Curl, for three decades one of
the industry's preeminent solid-state designer/engineers, But the
realizations of Curl's elegant circuits have typically been compromised by
cost-cutting parts substitutions-and sometimes, believe it not, by
unauthorized parts additions(!) -- at Parasound's manufacturing facility
But this time things would be different. Parasound CEO
Richard Schram, eager to produce a bulls-to-the-wall flagship amplifier,
commissioned John Curl to bring in Bob Crump and Carl Thompson, his
partners in CTC Builders, to create a truly great amplifier that could
sell for a less-than-stratospheric price tag. CTC Builders might be
thought of as a three-headed design superhero -- Curl designs the
circuits, Thompson engineers the board layouts, and Crump selects all of
the parts, wires, etc., and voices the final product.
CTC had already generated considerable buzz among
audiophiles with their no-holds-barred, custom-made-to-order Blowtorch
pre-amplifier (at $18,000). This writer had the privilege of reviewing the
Blowtorch for the late Ultimate Audio magazine. I, proud owner of the
tube-based Thor TA-1000 line and TA-3000 phono preamplifiers -- which had
for several years withstood comparisons to various ambitious competitors,
found the Blowtorch to be king of the mountain -- the finest audio
component in any category that I had ever experienced. Had finances
permitted I would have bought one right there.
Following the Blowtorch experience, I was most eager to
see what the CTC team could do with the mission of building monster
400-watt monoblocks that would retail for one-third the price of their
amazing preamplifier. I lobbied Curl, Crump and Schram, and in due course
a sweating UPS driver wrestled two large and heavy boxes into my garage.
"Beautiful brutes." That phrase popped into my
head after the JC 1s were unpacked, connected and powered up. The blue
front panel ON light was softly evanescent against the beautifully
finished silver-toned fascia. Why brutes? A closer inspection revealed
signs of amplifiers intended for serious business. The twin banks of
sharp-cornered heavy-duty heat sinks occupying both sides of the chassis
are impressive. Then there are the RCA and XLR input jacks, the bi-wire
loudspeaker terminals, and an unusual complement of back panel toggle
switches, for high/low bias selection, and trigger switches for automated
power up and down -- all aimed, I suppose, at the home theater market that
is a primary target for Parasound. Altogether, the visual presentation
belies the $6,000/pair retail price of the JC 1s. Had I just seen the
amplifiers with no preparatory information I would have figured the price
to be at least double, and possibly more.
The Epic Nobody Wants To
Break-In for the JC 1s was the longest and hardest I have
ever experienced, easily surpassing the former record holder, the
Meadowlark Blue Heron loudspeakers. Bob Crump had warned that I would have
to break in the RCA and XLR inputs separately, but that was the tip of the
iceberg. I ran the JC 1s 24/7 (with occasional power down and rest
intervals), into massive load resistors that got very warm to the touch,
for two months before attempting any critical listening. To my ear they
were not nearly ready. Subsequently, stopping to listen every few days, I
was increasingly puzzled not to hear the typical linear progression from
tight, stiff presentation to more relaxed musicality typically experienced
with new amplifiers. Rather, the JC 1s were chameleon-like, ever changing
- one time sounding wiry and edgy, another time flabby and bass-heavy.
These bizarre fluctuations reminded me of a conversation
years ago with Francis Mahoney, co-founder of Carneros Creek Winery and a
pioneer in upgrading the quality of California Pinot Noir. After I
complained that one of his three-year-old Pinots I had just opened had
lost the vibrant flavors it exhibited at release, Mahoney explained that
many Pinot Noirs go through a "dumb stage" before finally
settling into their characteristic flavors. Sure enough, a year later
another bottle of the same vintage drank beautifully. Altogether, I spent
four solid months of continuous break-in, especially through the balanced
inputs, before the JC 1s' sonic presentation became consistent enough for
Later, John Curl told me the first batch of JC 1s from
Taiwan had come over with steel XLR jacks rather than the specified
Neutriks, as well as a few other unauthorized departures from spec (To John's credit, he didn't ask me
to re-audition the JC 1s. As far as I know, other reviewers have not
experienced the extreme break-in duration I have described, and it may be
that my review samples indeed had some unique handicaps.
Life After Break-In!
Finally, the exasperating wait was worth it. It was
apparent from the first night of listening to the well-seasoned JC 1s that
here were extraordinary amplifiers. The JC 1s control loudspeakers as well
as any amplifier I have heard. They pump out seemingly effortless power no
matter how insanely loud I push them, with never any sense of strain such
as you hear when an amplifier is running out of gas. In that sense of
unlimited headroom the JC 1s are very similar to my 750-watt VTL Reference
The JC 1s are also capable of wondrous delicacy, and the
kind of transparency that makes you feel that you're hearing every
instrument, every voice, but never at the expense of the musical whole.
Tonality and amplitude are seamless from top to bottom. The bass
presentation, to my ear, is flawless -- all the transient speed and slam I
could ask for, coupled with a revelatory degree of subtle instrumental
differentiation -- able, for instance, to distinguish clearly the
combination of soft bass drum strikes, double basses and contrabassoon
playing in unison. At the other end of the spectrum, the top octaves seem
to extend virtually forever, with no distracting editorial brightness
imposed by the amplifiers.
Tube-like? Yes and no. The JC 1s, like the upscale
Blowtorch preamplifier, are free from the tonal and harmonic
characteristics so commonly ascribed to both tube (romantic lushness,
too-soft high frequencies) and transistor (leaner-than-life harmonic
structure, mid-treble grain and glare) designs. They serve the music
without imposing any distinctive sonic signature.
The JC 1s rank with the best amplifiers I have heard in
recreating a multidimensional sound field. Within the performance space
they render, individual vocals and instrumentals are stable and
consistent. For example, with these amplifiers I do not perceive the
Boston Symphony brass edging forward in full cry during the nonpareil 1962
Charles Munch Symphonie Fantastique (beautifully remastered on JVC
XRCD2 -- essential). Equally impressive is the impeccable scaling of
baroque virtuoso Andrew Manze playing Tartini's Devil's Sonata -- a
thrilling evocation of the single instrument interacting with a moderately
sized but reverberant space.
Unsurprisingly, the JC 1s are equally happy with
rock-'n-roll and other popular genres. I don't remember ever having more
fun with the Rolling Stones' great live album Get Yer Ya-Yas Out,
or becoming more absorbed into Miles Davis' landmark Kind of Blue (Classic
Records 2-LP reissue).
As I have suggested already, the JC 1s are great
amplifiers. To be able to buy these robust, delicate, emotionally
involving, brilliantly conceived and executed music recreators for $6,000
seems to me little short of a miracle. If I choose to stay with my beloved
($20,000) VTLs, that says more about me -- and my already owning them --
than about the JC 1s. Were I building an elite system from scratch, the JC
1s would be tough to pass up.
I would love to hear the JC 1s against some of the big
solid-state muscle amps going for three to six times their price -- Krells,
Levinsons, Rowlands, and the current hot-ticket favorite Halros. Who would
win? I dunno, But I have little doubt about who would win on
bang-for-the-buck. So, do these $6K monoblocks really belong in Superior
Audio? Believe me, the honor is ours.
Now that all that subjective opinion is out of the way,
let's take a different look at what CTC hath wrought. Note: the following
technical highlights are redacted from the considerably longer and more
detailed descriptions available from Parasound on the Web.
The JC 1 design is based on a complementary differential
J-FET input stage followed by two stages of selected push-pull MOSFETs,
ultimately driving 9 pairs of the most powerful complementary bipolar
power transistors available today. This produces 400 watts into 8 ohms,
800 watts into 4 ohms, and 1,200 watts into 2 ohms, without compromise.
In a sense, the JC 1 started in 1989 with the Parasound
HCA-2200 amplifier, which after a number of prototypes and modifications
over the years evolved into the HCA-3500. This amplifier is very powerful,
but it lacks the JC 1's much larger heat sinks, twice the power supply,
and better connectors, wiring, and circuit layout. The JC 1's "Class
A" output is over 25W, so that in normal listening the amplifier
operates entirely in Class A, extending to Class AB only during very loud
passages, large bass transients, etc.
Bob Crump asserts that the sonic excellence of the parts
selected for the JC 1 is unprecedented in an amplifier anywhere near its
price range. Those parts include Vampire Direct gold-plated OFC RCA jacks,
Neutrik XLR connectors, Reliable RT DC bypass and Zobel capacitors,
Superior Electric binding posts, Vampire continuous cast copper signal and
DC wiring, Nichicon Great Supply raw DC capacitors (132,000uF in the
high-current supply), Nichicon Muse DC and local bypass capacitors, Harris
hyperfast soft-recovery diodes for all bridge rectifiers, and Sanken
output transistors, the most powerful complementary transistors available.
The JC 1 has separate power supplies for the input/driver section, making
it immune to fluctuations in AC line voltage.
Circuit functions are divided between four separate,
carefully oriented circuit boards and their associated wiring to minimize
unwanted circuit interactions. System signal flow emphasizes overall
system grounding. The final main board can handle double the very
substantial current the JC 1 can deliver. This capacity requires very wide
matched circuit paths in 2 oz. copper on both sides of the board for
Audible strain due to layout-generated resistance is
negligible. The beefy layout accommodates the huge power supply, which
comprises four large filter capacitors, plus the separate input stage
power supply on the main circuit board. The separate dedicated input board
is thus more immune to power supply and circuit noise. The input board
mounts directly on the back panel for minimum wiring length. The layout is
symmetrical, with the shortest possible signal paths.
Power Supply: The heart of the power supply is a 10
ampere (continuous) toroidal transformer encapsulated in an epoxy-filled
steel canister to ensure ultra-quiet performance.
The high-voltage B+ and B- supply rails for the output
stage use high-speed fast-recovery rectifier diodes and four 33,000 uF
Nichicon electrolytic filter capacitors. These filter capacitors are
bypassed with smaller polypropylene capacitors to reduce AC ripple in the
DC supply and further eliminate AC noise and interference generated by
computers and other appliances.
Relay-Bypassed Soft Start Circuit: When the JC 1 is
turned on, significant inrush current is required to charge the power
supply capacitors. To suppress this inrush current and prevent nuisance
tripping of circuit breakers, NTC (negative temperature coefficient)
resistors reduce the inrush current by 50 percent. After that, a gold
contact relay activates to completely bypass the NTC resistors to ensure
that they do not restrict the power supply during operation.
Complementary Configuration: Each stage of
amplification uses NPN transistors fed by the positive DC power supply and
complementary PNP transistors fed by the negative DC power supply. This
complementary topology is inherently linear, which reduces distortion and
improves sonic accuracy.
Input Stage: The JC 1's input stage uses matched
pairs of discrete JFETs arranged in a differential configuration. JFETs
are ideal for the input stage because their inherently high impedance is
unaffected by the impedance of source components. Differential
configuration provides superior noise reduction. These precision input
JFETs are also cascaded to produce the current necessary to drive the
MOSFET drivers in the following stage.
Driver Stage: The driver stage employs
complementary matched pairs of MOSFETs selected for their tube-like sonic
qualities. MOSFETs tend to generate less odd-order harmonic distortion
than bipolar transistors. This is important because odd-order distortion
sounds unnatural and fatiguing to the human ear, whereas even-order
distortion is less offensive because it is consonant, rather than
dissonant. The B+ and B- power for the input and driver stages cannot sag
under load because it is supplied by independent transformer secondary
windings with independent rectification, filtering and voltage regulation.
This preserves soundstage width and depth even when the JC 1 output stage
is drawing enormous amounts of current.
Output Stage: The JC 1's output stage employs nine
pairs of high-current (15-ampere) bipolar transistors to ensure long-term
reliability with continuous high power operation and challenging speaker
loads. Lightning-fast (60MHz) transistors respond instantly to complex
demands in the musical signal, virtually eliminating distortions that
occur with slower transistors. Slew rate limiting and Transient
Intermodulation Distortion (TIM) are simply not an issue.
"Class A/AB" Operation: Pure "Class
A" operation provides the purest sound. However, an amplifier
operating entirely in "Class A" operation would be enormous,
highly inefficient, and generate too much heat. "Class AB"
combines some of the advantages of "Class A" with the efficiency
of "Class B" operation. It is a compromise that reduces the heat
generated in pure "Class A" operation and the odd-order harmonic
distortion created in "Class B". In "Class AB", the
driver and output stages are always turned on, which provides a nominal
amount of pure "Class A" operation. The JC 1 input and driver
stages are 100% pure "Class A", while its output stage provides
up to 25 watts of pure "Class A".
DC Servo: Direct Current (DC) burns out speakers.
Therefore, every power amplifier must have some way to ensure that DC from
its power supply never reaches its + or - speaker terminals. Most
amplifiers use trim controls to reduce DC offset or capacitors to block
DC. Unfortunately, trim controls can allow DC offset to increase over
time, and even the most expensive capacitors in the audio signal path will
veil sonic clarity and attenuate bass response. The JC 1 incorporates
fast-acting DC servo circuits, eliminating the need for coupling and
blocking capacitors. The JC 1 is direct-coupled from input jack to speaker
terminals. This circuitry never needs adjustment or maintenance. It
operates outside the audio signal path to keep the DC offset at the output
of the JC 1 at a constant 0.00 Vdc.
Relay Protection: When the JC 1 is powered on, the
protection relay remains open for three seconds while the positive and
negative power supplies stabilize. This prevents annoying popping or other
transient noises. Relay protection also prevents speaker damage in case of
a catastrophic amplifier failure.
Over-Current Protection: Current-sensing
transistors connected to the output stage constantly monitor current flow
through the output transistors. If the current exceeds a predetermined
safe level due to load impedance below 1 ohm or a short circuit at the
speaker terminals, the output relay opens immediately to prevent output
transistor or other parts failure.
Fuse Protection: Separate fuses for the positive
and negative DC voltage rails provide backup protection in case the
over-current protection does not work in time or an internal part fails.
In the event of a part failure, these fuses halt operation to minimize
damage to additional parts.
Chassis: The chassis is heavy-gauge aluminum.
Aluminum is non-magnetic and cannot be energized by high voltage and
current flow, thereby removing a potential cause of "smearing"
or other audible intrusion.
RMS Power, 20Hz to 20kHz:
400 watts continuous, 8 Ohm
800 watts continuous, 4 Ohm
1200 watts short term, 2 Ohm
Class A Power, 20Hz to 20kHz
25 watts, bias set to high, 8 Ohm
10 watts, bias set to low, 8 Ohm
Current Capacity: 135 amperes peak
Slew Rate: >130 V/µsecond
Frequency Response: 2Hz to 120 kHz (+0/-3dB)
Total Harmonic Distortion: <0.15% at full power; <
0.018% typical levels
IM Distortion: <0.03%
Dynamic Headroom: >1.8dB
Input Impedance: Balanced 100 k Ohms; Unbalanced 50 k Ohms
Balanced - 1 V for 28.28 V output into 8 Ohms
Unbalanced - 1 V per leg for 28.28 V output into 8 Ohms
Signal to Noise Ratio:
>122dB, IHF A-weighted, bias set to low
>120dB, IHF A-weighted, bias set to high
>113dB, Unweighted, bias set to low
>111dB, Unweighted, bias set to high
Damping Factor: >1200 at 20Hz
DC Trigger Requirements: +9 Vdc to +12 Vdc, 2 mA
Audio Trigger Requirements: 50-250 mV AC
DC Trigger Output Capacity: +12 Vdc, 150 mA
Total Width: 17.75 x 7.8 x 20 (WxHxD in inches)
Net Weight: 64 lb.
Price: $6,000 per pair
Parasound Products, Inc.
950 Battery Street
San Francisco, CA 94111
Voice: (415) 397-7100
Fax: (415) 397-0144