Parasound is now shipping its John Curl designed Halo JC 3 Phono Preamplifier, a high-performance dual-mono phono preamp 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.
The Parasound Halo 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.
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 83 dB with the MM input and 73 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 115V-60Hz/240V-50Hz AC power input for use around the world.
As Parasound's chief amplifier circuit designer, John Curl has helped create dozens of the company's best products. Nearly 20 years ago he also designed the Vendetta Research SCP2B that is still regarded by many audiophiles as the preeminent phono preamp.
“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 Parasound's president and founder, Richard Schram. “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.”
Price and Availability
The Parasound Halo JC 3 is now available with a suggested retail price of $2,350.