Phono Preamplifier by John Curl
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Golden Ear Award Winner 2014 – The Absolute Sound
Upgrade of an Already Legendary Phono Stage
How do you improve a phono stage that was named a “Recommended Component” by Stereophile and won an Editors’ Choice Award from The Absolute Sound, to name just a couple of honors received by the Halo JC 3? For the answer, just ask Parasound’s president and founder Richard Schram. He’s made a proven winner even more spectacular with the Halo JC 3+.
Variable MC Load Impedance with Custom Vishay Pots
The original Halo JC 3 was designed by legendary audio designer John Curl, and he also did the honors with the JC 3+.
The new model includes a whole raft of improvements over the original, beginning with variable MC load impedance adjustment of 50-550 ohms for each channel using dual gang potentiometers specially made for Parasound by Vishay. This enables precise adjustment to optimize the sound of any MC cartridge. Vishay custom builds these potentiometers for Parasound, and John Curl agreed to adjustable input load only if Parasound used Vishay pots. Getting Vishay to make the pots wasn’t an easy deal. Vishay is a large company, and six months of the JC 3+ development time was spent in negotiations with them to build the custom potentiometers for Parasound. So this is a very big deal indeed.
“Simply Overflowing With Positives”
The JC 3+ won a Golden Ear Award Winner for 2014 from The Absolute Sound magazine. According to Neil Gader, “For those who are prone to swapping exotic cartridges and seeking the last work in resolution, the new ‘+’ is simply overflowing with positives.”
“If you go from one of the modest priced phono preamps analogplanet.com surveyed last year to the JC3+, you’ll have no trouble hearing the sonic improvement. And as you upgrade cartridge and turntable the JC3+ will comfortably go along for the ride,” notes Michael Fremer in his AnalogPlanet.com review for April 17, 2014.
Circuit Board Enhancements
The circuit board layout in the phono modules has been tweaked to further reduce its silent background noise. John Curl reduced 1/f “shot noise” going into the input stage. The copper traces on the phono module boards are 24k gold plate for utmost conductivity and most transparency/detail in the music. As Richard Schram puts it, “The ultimate electrical conductor achieves the ultimate transparency.”
Greatly Upgraded Power Supply
The JC 3+ uses 47 percent larger low ESD power supply filter caps, which provide greater reserve for head-snapping dynamics. The additional reserves enable even greater bass slam and impact.
The R-core power transformer capacity has been increased by 82%, providing greater reserve for low end impact that’s beyond imagination. The large power supplies also improve the sound of very low level signals. Furthermore, the signal-to-noise ratio is improved to 87dB A weighted. According to Richard, the result is that “while the JC 3 background was utterly black, the JC 3+ black is blacker.”
Even More Enhancements
That’s hardly the end of the enhancements. Gain has been changed to 48dB MM and 64dB MC. So that high output MC cartridges won’t overload some line stage preamps. The front panel P logo illumination can be switched off with the JC 3+, since some people prefer not seeing it. And the JC 3+ is available in both black and silver.
John Curl-Designed Premium Phono Stage
So how did the original JC 3 come about? When Richard Schram decided to build a no-holds-barred phono stage that was the equal of the company’s Halo JC 2 preamp and Halo JC 1 monoblocks, he went straight to the top. He asked legendary audiophile designer John Curl to create the Halo JC 3.
“It took me a while to persuade John Curl to make a free-standing phono stage for Parasound,” Richard Schram reports. “He is very protective of his reputation as one of the truly great phono preamp designers.”
As Parasound’s chief amplifier circuit designer, Curl has helped create dozens of the company’s best products. Nearly 20 years ago he also designed the Vendetta Research SCP2B, which is still regarded by many audiophiles as the preeminent phono preamp.
Stereophile honored the Parasound Halo JC 3 phono preamp by including it in its “Recommended Components” list for 2013. “The Halo JC 3 produced a detail-rich sound with tight, extended lows, a clean midrange, and carefully drawn images on a huge, open soundstage,” said the magazine.
“A Heady Mix Of Profound Silence And Kick-Butt Energy”
The Parasound Halo JC 3 won an “Editor’s Choice Award” for 2012 in The Absolute Sound magazine, which noted, “Sonically, there’s a riveting balance of extremes at play here: a kiss of romance through the mids and an ability to extract and define low-level information in acoustic space.”
Very Clean, Very Quiet Dual Mono Design
The Halo JC 3+ is a high-performance dual-mono phono preamplifier built with high quality parts, solid construction, and a very clean design. Like all phono preamplifiers, the JC 3 must multiply the tiny audio signal generated by a high-end low-output moving coil or moving magnet phonograph cartridge and make it strong enough to deliver to the input of a line level preamplifier. However, because phono signal levels are so weak, the slightest bit of noise and distortion in the system can easily compromise the musical experience.
“After working with John Curl and circuit board designer Carl Thompson, we are convinced that one of the most important elements of phono preamp design is to use the smallest possible amplifier circuit with the least amount of copper to act as an antenna for noise,” said Richard. “Indeed, the actual phono gain circuits are relatively small within the JC 3’s 18 lb chassis. To keep the background black and silent I insisted on housing each channel in its own extruded aluminum enclosure, each further isolated from the power supply with 3/8-inch thick low-carbon mild steel partitions. All parts are top quality with Vishay-Dale resistors used exclusively and REL capacitors in critical circuits. In fact, the passive EQ parts values and quality are the same as in the original Vendetta.
“This project has taken several years,” Schram continues, “but after listening to the end result it was worth every minute. Curl’s Vendetta was so good that it was almost magical, but each one was essentially hand made, and would probably cost over $8,000 to build today. Now, Parasound has a new design that draws from the same creative genius while offering amazingly high performance from each piece we produce.”
Connections and Cartridge Loading
The JC 3+ is a dual mono design with unbalanced inputs and outputs using Vampire RCA jacks, plus balanced outputs using Neutrik XLR jacks. A custom-made three-position input impedance switch provides for 47 k ohm MM cartridges, 100 ohm MC cartridges, and 47 k ohm MC. The latter is an ideal load for some MC cartridges and high-end moving iron cartridges.
The direct-coupled amplification circuits use DC servos rather than coupling caps. FET followers on each channel’s board are used to further isolate the circuits from the voltage regulators in the power supplies.
Super-Quiet R-Core Transformer
The JC 3+ uses dual mono power supplies with an R-core rather than a toroidal transformer, since toroids have very high capacitive coupling between their primary and secondary which enables noise on the AC line to pass into the power supply and ultimately into the phono gain stages. To further assure immunity from noise on the AC line the JC 3+ includes a built-in AC line conditioner.
All these efforts have lead to a phono preamp with impressive performance. The JC 3’s signal to noise ratio is 87 dB with the MM input and 75 dB for MC, and the RIAA curve is accurate to within 0.2 dB. It is quiet enough to excel with even the lowest output premium phono cartridges.
Other features include manual or auto turn-on via a 12V trigger input, an AC line polarity reverse switch to eliminate hum in many systems, and a switchable 115 V, 60 Hz / 240 V, 50 Hz AC power input for use around the world.
|Dimensions||17.5 × 4 × 16 in|