By Lisa Johnston
New products on display at the American International Toy Fair, held in N
San Francisco – Parasound plans late-December shipments of an improved version of its Halo JC 3 phono preamplifier.
The new Halo JC 3+, available in silver and black at a suggested $2,850, adds independent load adjustment for moving-coil (MC) cartridges, enhancements to the dual-mono phono-module circuit boards, and enhanced power-supply capabilities.
It will be displayed at International CES at Venetian Veronese 2501A.
The previous version eschewed variable-load adjustment because potentiometers generally create more noise, com compared to fixed resistors, the company said. As a result, the original JC 3 was built with limited switched-input load-impedance choices to the disappointment of some vinyl enthusiasts who contend input-load fine-tuning is “essential” for certain cartridges, the company noted.
Designer John Curl and circuit board designer Carl Thompson eventually relented but required that the potentiometers comply with stringent performance requirements and be manufactured by Vishay, the manufacturer of low-noise electronic parts, Parasound said. Previously, Vishay did not offer a potentiometer that met these specific requirements.
The resulting JC 3+ features independent variable MC-load fine adjustment capability for each channel from 50-550 ohms using low-noise dual-gang potentiometers.
Other performance improvements included a narrower spectrum of Johnson/Nyquist noise in the resistor that loads the input stage, tweaked phono-module board layouts to further optimize performance, and copper circuit board traces that are now 24-karat gold-plated where each part is soldered to provide “unprecedented transparency and musical detail,” the company said.
The MC signal-to-noise ratio grew from 75dB to 87dB, A-weighted. MM gain was increased from 47dB to 48dB, and MC gain was lowered from 68dB to 64dB so that extra-high-output MC cartridges won't cause the JC 3+ to overload the inputs of some line-stage preamps, the company said.
The JC 3+ power supply was upgraded to allow for much greater current reserves to boost dynamics, and a larger R-core power transformer provides greater reserves for bass impact, the company also said.
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