12OPERATING YOUR JC 2 continued/DESIGN OVERVIEW
Polarity Normal & Invert Buttons
The polarity (or phase) of the Main Outputs is the same as the input unless you press the Invert button to invert the polarity of the Main Outputs 180° relative to the input signal. Pressing the Normal button restores normal 0° polarity of the Main Outputs.
For more information on when to invert polarity, please see the Frequently Asked Questions on page 13 of this manual.
Parasound Tuner Buttons
These buttons will control Parasound Halo Tuners such as the T 3. They select FM or AM band and allow you to scroll through its presets.
“Burning-in” Your JC 2
Like many other great high end preamplifiers, your JC 2 should operate for at least 72 hours with music playing (any volume level is ok) after it is first turned on before it will sound its best. This gives various internal components and wiring a chance to “form” their optimum electron pathways so they can pass complex musical information with greater definition, smoothness and transparency. Although your JC 2 will sound spectacular when you first turn it on, you will come to appreciate it even more as your listening hours accumulate. You’ll discover additional musical details you may not have known were present.
Maintaining Your JC 2
Your JC 2 requires no periodic maintenance and has no user serviceable parts inside. To avoid risk of electric shock do not remove the top cover. To keep it clean use only a soft cloth moistened with a few drops of clear water or Windex. Never use any solvents or abrasives. The remote control handset batteries should be removed whenever it will be unused for an extended period. Remove the battery cover annually to inspect and remove leaking batteries.
DESIGN OVERVIEW
John Curl’s symmetrical circuits are well-respected and give the listener the best chance to experience the full emotional content of the source. In the JC 2 the physical implementation of the circuits closely follows the circuit topology and the layout is as literal as possible, commensurate with isolation of disparate or out-of-phase signals. All component parts are oriented for minimum interaction. The high current, low impedance audio power supply is larger than many amplifiers and carefully integrated with the signal boards. The resulting musical output blooms with both absolute musical authority and clarity.
The chassis and PCB layout of the JC 2 are uncompromised in their pursuit of the highest design goals for a preamplifier. The shortest signal path is achieved by placing the master volume control and individual channel level potentiometers and high quality gold-plated input select relays right where the input circuitry is located to eliminate the need for long wires and traces. Each channel is on a separate PCB. The preservation of low level signals is achieved by the separation of critical audio signals from non-audio circuits. The audio power supply, control power supply and control circuits also have dedicated PCBs. To prevent the possibility of radiated noise getting into an audio circuit the power supplies and control functions are further isolated from each other by two 3/8 inch thick aluminum partitions that are the full height of the chassis and run side-to-side and front-to-back. The entire signal path is embedded on circuit boards in a continuous ground plane or carried in professional-grade Canare® shielded wires. Even within the audio circuit’s power supply section, AC power is isolated from regulated power by placing the power transformer high in the chassis on one of the aluminum partitions.
The power transformer is an R-core type, which has the advantage of a toroid transformer for minimizing radiated hum but is superior at preventing noise carried on the AC power line from passing into its secondary windings. Ground return paths are low resistance, with substantial planes and thick wires, and sequenced precisely. Non-audio control circuitry, LEDs, relay coils and the motor for the master volume control are powered by a separate power supply whose transformer has a separate ground return. The resulting extremely low noise levels enable musical nuances to overlay an utterly silent background.
