Parasound JC3+ High End Phono Stage MM/MC

The new Parasound JC3+ Plus adds independent load adjustment for moving coil cartridges, as well as enhancements to the dual-mono phono module circuit boards, and increased power supply capabilities. The JC 3+ circuit comes from the designer of the legendary Vendetta phono preamp, John Curl. During the design phase of the Parasound JC3 Plus, Curl had rejected variable load adjustment because, compared with fixed resistors, potentiometers generally have higher intrinsic self-noise, which is an anathema to creation of an ultra-low noise phono stage. Curl prevailed (he always does), and the JC 3 was built with limited switched input load impedance choices. This decision disappointed some vinyl enthusiasts and reviewers who consider input load fine-tuning to be essential for certain cartridges.

Curl and circuit board designer Carl Thompson eventually consented to including variable load impedance adjustments, but with these caveats for the potentiometers: 1) They must comply with stringent performance requirements. 2) They must be manufactured by Vishay, a highly-regarded manufacturer of low-noise electronic parts. At that time Vishay did not offer a potentiometer that met these specific requirements. However they recognized an opportunity, and eventually agreed to develop the part and manufacture it in small quantities for Parasound. The outcome of this effort is the Parasound Halo JC 3+.

Naturally, the JC 3+ features independent variable MC load fine adjustment capability for each channel from 50-550 ohms using these special low-noise dual-gang potentiometers. Parasound also took the opportunity to make additional performance improvements. Curl narrowed the spectrum of Johnson/Nyquist noise in the resistor that loads the input stage to maximize its low noise capabilities. Circuit-board designer Carl Thompson tweaked the phono module board layouts to further optimize every performance parameter. The copper circuit board traces in the phono modules are now 24 karat gold-plated where each part is soldered to provide unprecedented transparency and musical detail.

The MC signal to noise ratio is improved from 75dB to 87dB, A-weighted. MM gain has been increased slightly from 47dB to 48dB, while MC gain has been lowered from 68dB to 64dB so extra-high output MC cartridges won’t cause the JC 3+ to overload the inputs of some line stage preamps. The JC 3+ power supply has also been significantly upgraded with 47 percent larger low-ESD power supply filter capacitors. This provides much greater current reserves for head-snapping dynamics. A new R-core power transformer is 82 percent larger to provide greater reserves for low-end impact that’s beyond imagination. Finally, at the suggestion of a few JC3+ customers, the company has added a simple on/off switch for the front panel P logo illumination.