Parasound Halo JC 1+ Mono Power Amplifier
The origin of the JC 1+
An audio historian could make a persuasive case that our new Parasound Halo JC 1+ is the most ambitious and extraordinary achievement since I stablished the Parasound brand in September 1981.
For almost 40 years our mission has remained the same: build audio components that sound better, measure betterand last longer than our competition, at prices that are sensible. We call this “value engineering.” It challenges us and guides every decision we make for every product we build.
The origins of the JC 1+ go back to 1989 when we engaged the legendary John Curl to design our power amplifiers. These were very successful, so in 2000 we commissioned Curl to develop the JC 1. Released in early 2003, the JC 1 immediately earned the respect and admiration of reviewers and audiophiles
alike. It set new standards of performance and value that were unrivaled during its 16 years in production. In fact, the last JC 1 to come off the production line
sounded just like the first JC 1. There were no “improved” versions during its entire product life -- simply because the JC 1 design, development, and manufacture made it so far ahead of its time.
A few years after the JC 1’s introduction, consumers and dealers began asking when we planned to build an improved JC 1. After all, this is a common practice in the audio industry (which makes me wonder, why couldn’t they get it right in the first place?). My reply was always the same: “We could make changes to increase its price, but none that would materially improve performance. Yes, we could make a more expensive JC 1 and, if we were lucky, it might sound as good as the existing JC 1.
In early 2014, John Curl announced that he was investigating ideas that could substantially improve the JC 1 performance. As all Curl’s theories are based on
objective science, not wishful thinking or self-suggestion, I was all ears. It’s prudent to be skeptical of new ideas, and we were. So Parasound hand-built six experimental prototypes to test Curl’s theories. What we measured and heard were nothing short of astonishing.
The JC 1+ decisively outperformed the JC 1 in every respect.
New insights
Most amplifier manufacturers don’t allocate resources to develop their input and driver stages because they either fail to understand their critical role or they just don’t want to spend the money. Curl, on the other hand, knows that an amplifier can only be as good as its input stage. Input and driver stages that provide the amplifier’s voltage gain have a significant influence on an amplifier’s performance. If an amplifier’s input and driver stages are even slightly deficient, the very best output stage cannot make up for its shortcomings. Such an amplifier won’t meet our standards.
Curl addressed the most prevalent shortcomings of amplifier input stages. First among these is distortion that originates in the input stage. Even the slightest amount of input stage distortion becomes significant by the time it reaches the amplifier’s output stage and ultimately, your speakers.
Input stage distortion is often caused by insufficient power supply voltage. Any amplifier will distort if its input and driver stage B+ and B- power supply rail voltage “sags”. Yet in virtually all amplifiers, the input stage power supply is shared with the output stage supply. Typical input stages and driver stages derive their operating voltage from the output
stage power supply. This invites distortion whenever the amplifier is played at high volume.
Voltage drops occur when the power transformer, bridge diodes and filter capacitors aren’t substantial. The original
JC 1 avoided voltages drops by equipping its power transformer with additional secondary windings solely for the input and driver stage power supply.
The Halo JC 1+ goes a step further with the addition of a separate power transformer dedicated to the input and driver stages. This second power transformer supplies ± 89V to high-speed soft-recovery bridge diodes and Nichicon filter capacitors totaling 22,400uF, resulting in rock-solid ±112Vdc for the B+ and B-
“rails” when the amplifier’s output stage is operating at its maximum capacity.
