Parasound JC 3+ Phono Preamp

Déjà-Vu and Then Some

Equipment report
Categories:
Solid-state preamplifiers,
Phonostages
|
Products:
Parasound JC 3+
Parasound JC 3+ Phono Preamp

First, hats off to Parasound for not bowing to convention and badging its new, hot-rodded version of the original JC 3 phonostage with the shop-worn cliché “Reference” or “Signature Edition.” And second, and more importantly, if you’re a current owner of the Parasound JC 3 phonostage, don’t panic. It’s still a great phonostage, except now it has company— the JC 3+—priced $645 above the original’s $2350.

As readers will recall, the original JC 3 clinched a Golden Ear Award not long after I reviewed it in Issue 215. I stated at the time that this full-chassis, dual-mono design featured “a near obsessive attention to isolation,” to the extent that each channel was housed in its own extruded aluminum enclosure within the chassis, and further isolated from the power supply with 3/8"-thick, low-carbon mild-steel partitions. It remains, in my view one of the most worthy phonostages on the market. But audiophiles are a finicky bunch and the JC 3’s lack of variable loading stuck in the craw of some. Taking notice, Parasound tasked phono wizard John Curl to work his magic once again. Curl’s wand-waving not only resulted in loading adjustments but a chassis full of other improvements as well.

The story goes that during the design phase of the original JC 3, Curl had rejected variable-load adjustment due to the added noise intrinsic in potentiometers. As a result the JC 3 was built with limited, switched-input load-impedance choices. In a short interview accompanying my original JC 3 review Curl’s remarks turned out to be prescient: “Actually I think I underestimated the market. Most phono cartridges don’t require a whole lot of big extremes and I thought on this particular point people wouldn’t be using the most exotic cartridges, so I kept them to a minimum with 100 ohms and 47k for the moving coil and 47k for the moving magnet...We might even consider adding more loading if people complain enough.”

Evidently the market did indeed pipe up. But Curl and circuit-board designer Carl Thompson needed to be convinced they could get the required performance to make the change worth pursuing. They turned to Vishay, a top manufacturer of low-noise parts, which ultimately agreed to develop a potentiometer and manufacture it in small quantities for Parasound. The JC 3+ now features independent, variable-load fine-adjustment capability for moving coils in each channel, ranging from 50–550 ohms using Vishay’s special low-noise dual-gang potentiometers.

As it turned out there are lot more positives to the JC 3+ than variable loading. Curl and Thompson tweaked the phono-module boards to further optimize every performance parameter. The copper circuit-board traces in the phono modules are now plated with 24-karat-gold at the junction where each part is soldered. Turning to numbers the moving coil signal-to-noise ratio is improved from 75dB to 87dB, A-weighted. Moving-magnet gain has been increased slightly from 47dB to 48dB, but mc gain has actually been reduced from 68dB to 64dB so that very-high-output mc cartridges won’t cause the JC 3+ to overload the inputs of some linestage preamps. The JC 3+ power supply has also been significantly upgraded with 47% larger, low-ESD power-supply filter capacitors for greater current reserves. Finally the new R-core power transformer is 82% larger to provide better bass performance. One ergonomic nitpick: The inputs and pots are deeply inset on the back panel so that only the smallest fingers need apply when trying to reach the spring-loaded release buttons of a typical pair of balanced XLR interconnects.

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