10
Front Panel Controls
On-Off Button
Push once to turn on the JC 3+. There will be a slight delay as the circuits stabilize and the
DC servos settle down. When the JC 3+ is turned on the blue glow around the On-Off button
will be brighter and the red P badge will glow brighter. Push again to turn off the JC 3+.
Note
: This button is disabled when the Turn On Options switch (on the rear panel)
is set to 12 V.
Mono Button
Press the Mono button one time to parallel the stereo channels to mono. Press it a second
time to return to stereo. Older mono records and stereo records with high levels of rumble will
sound cleaner when you select mono on the JC 3+. The Mono button glows blue when
stereo is selected and glows amber when mono is selected.
Design Overview
John Curl’s phono preamps are legendary. His approach to amplifying extremely low level
signals gives the listener the best chance to experience the full emotional content of the source.
In the JC 3+ the physical implementation of the circuits closely follows the actual circuit topology
and the layout is as compact as possible to minimize pickup of external noise.
The preservation of low level signals is achieved in several ways. The phono module circuit
boards are 14k gold plated for optimum electron flow. They are further protected by physically
separating these critical audio signals from the non-audio circuits and non-audio wiring. Each
channel has its own circuit board and each channel is fully enclosed in its own extruded
aluminum “vault.” This vault shields the sensitive circuits from the JC 3+’s power supply and from
external sources of noise.
The JC 3+ power supply uses a high capacity 1 ampere R-core power transformer. R-core
transformers share the advantages of a toroid transformer for minimizing radiated hum. However,
it is far superior to a toroid transformer in preventing noise carried on the AC power line from
passing through to its secondary windings and into the power supply. 40,000uF of filter
capacitance assures you will hear all of the dynamic contrasts that give additional life and
presence to your LPs.
A second level of shielding separates each phono vault from the power supply, power
transformer and even the transformer wires running to the AC inlet on the rear panel. This
shielding consists of two partitions of 3/8” low carbon “mild” steel to prevent any electromagnetic
radiation from reaching the phono modules. The rear panel of the JC 3+ is made of aluminum to
prevent any electromagnetic interaction with the sensitive phono circuitry.
The JC 3+ has an on-board AC line conditioner to filter out high frequency noise and
distortion that may be present on your AC power line. This eliminates a potential source of noise
before it ever reaches the JC 3+ power transformer. The resulting extremely low noise levels
enable musical nuances to emerge from an utterly silent background.
