A five-year effort by Curl and Parasound, and sweeping circuit improvements, have resulted in the amazing Parasound Halo JC 1+ monoblock amplifier. With 450 watts into 8 ohms, 850 watts into 4 ohms, 1300 watts into 2 ohms, and a peak current of 180 amperes, the JC 1+ excels even with speakers that can dip to 1 ohm. It operates in pure Class A up to 25 Watts and Class AB to full power, reflecting Curl's attention to detail and sound quality.
"In early 2003, the JC 1 was an immediate success," said Richard Schram, Parasound's president. "We couldn’t imagine how to improve it. I was surprised and excited when John called me in early 2014 to discuss his ideas for a new amplifier that would significantly outperform the JC 1. During 2015 and 2016 we built numerous prototypes to confirm Curl’s theories, and the sonic improvements he’d predicted. The results were outstanding. We decided to create a new amplifier to honor the JC 1’s legendary reputation. The JC 1+ is a technological masterpiece, raising the bar for amplifier performance and value for years to come.”
At 83 pounds, the new JC 1+ is 30 percent heavier than the JC 1. Its new power transformer has 20 percent higher capacity, while additional Nichicon power-supply filter capacitors increase from 132,000 uF to 198,000 uF. The new amp boasts 24 Sanken 15A/230V output transistors compared to 18 — a 33 percent peak current increase, for music that truly soars.
The Parasound Halo JC 1+ is remarkably quiet and is the first commercially built product to employ active high-frequency noise filtering with Bybee Music Rails™, eliminating input stage noise that compromises sound quality. Curl’s newly designed driver stage employs a cascade circuit with greater open-loop bandwidth and increased linearity. In another first for the JC 1+, the input and driver stages reside on FR-408 printed circuit board material. Until now FR408 was used in super-computer and aerospace applications. The input-stage power supply is totally independent from the main power supply. Its R-core transformer isolates sensitive circuitry from high-frequency power line noise. This input stage power supply employs quiet high speed/soft recovery diodes and 22,400 uF filter capacitance, to deliver +/- 112 VDC rail voltage, virtually eliminating distortion. Premium Wilson Audio REL capacitors use a proprietary design, which resists micro vibrations that typically degrade the sound quality of other caps. The addition of an XLR Loop Out as well as a 12V-trigger/delayed-turn-on improve the connectivity and utility when multiple JC 1+s are used in bi, tri, and quad amp configurations.
Parasound’s Halo JC 1+ has a fast-start bias circuit that enables it to sound its best within minutes after turn-on. A bias level selector switch enables cooler operation, with virtually no performance compromise. To optimize performance with high gain preamps and high sensitivity speakers, a two-position toggle switch selects 23dB or 29dB gain.
Premium Neutrik balanced locking XLR connectors, and Vampire unbalanced RCA output connectors facilitate bi-amping. Rugged Parasound-designed CHK Infinium speaker terminals accept spade lugs up to 16mm wide, banana plugs, and 5-AWG bare speaker wire. The front panel design not only matches the updated Halo family appearance, but also complements the inner beauty of the JC1+.
Positive Feedback by Greg Weaver
Stereophile by John Actkinson
How does the JC1 differ from the JC 1+?
400 → 450 Watts @ 8Ω
800 → 850 Watts @ 4Ω
1200 → 1300 Watts @ 2Ω
Filter capacitance: 132,000 → 198,000 uF
Transformer capacity: 1.9 → 2.1 kVA
Output transistors: 18 → 24 Sanken 60Mz devices
Peak current: 135 → 180 amps
Weight: 64 → 83 lbs net
Bybee Music Rails™ active high frequency noise filters
John Curl driver stage employs a new cascode circuit design
FR-408 input circuit board material improves HF signal integrity
Gain switch to select 29 dB or 23 dB of gain
R-core power transformer for input stage
Input circuit board is shielded
Double thickness copper on output/power supply circuit boards
Gold-plated internal audio signal path connectors
Custom CHK Infinium speaker binding posts
Looping Neutrik XLR output for easier bi-amping
Front panel power indicator LED
Updated auto turn on circuits with 3.5mm 12V trigger jacks