Specification Sheet

Supremely silent
Curl is a master at eliminating undesirable electronic noise. For the JC 1+ he specified a pair of Bybee Music Rails
TM
,
which are active high frequency noise filters that “scrub away” every vestige of noise on the input and driver stage
B+ and B- rails. These ingenious and patented devices were conceived by Jack Bybee and invented by an eminent
microwave engineer and audiophile in collaboration with Curl and noted circuit board designer Carl Thompson. Carl is
known for designing the circuit boards for Curl’s Vendetta Research phono stage, and the Parasound JC 1, JC 2 BP,
JC 3+ and JC 3 Jr. To optimize their effect, Carl designed Music Rail circuit boards exclusively for the JC 1+. The
JC 1+ is the first commercial product to employ these remarkable devices.
As in the JC 1, the JC 1+ input stage uses hand-matched pairs of
Toshiba 2SJ74 P-channel and 2SK170 N-channel J-FETs. These
coveted devices remain unmatched for their low noise. Parasound
is one of the few companies that has invested heavily to secure an
ample stock of these rarest of all J-FETs.
The JC 1+ employs FR408 circuit board substrate for the critical
input and driver stages. FR408 was invented for ultra high-speed
applications in super computers and aerospace. Carl recommended
FR408 for its superior propagation of high frequencies that
outperforms Delrin. Our obsession with eliminating noise that
pollutes sound quality led us to add shielding to this board to isolate
it from internal stray currents that might diminish its perfection.
The JC 1 driver stage was an excellent single-stage circuit. Curl
predicted that a two-stage cascode driver would make a substantial performance improvement because a driver circuit
with cascode topology has some of the favorable attributes of vacuum tubes, namely higher input-output isolation,
higher input impedance and higher output impedance. Its greater bandwidth and open loop gain were expected to
improve linearity and a noticeable improvement in sound quality. This proved to be true.
High current is imperative
Curl affectionately referred to the JC 1 as a “stump puller” because its 135 amp peak current enabled it to drive any
commercially manufactured speaker with ease. Over the years, he has observed an increasing number of high-
performance speaker manufacturers employ lower impedance to achieve their sonic objectives. Impedance dips below
2 ohms are not uncommon. Such punishingly low impedances increase an amplifier’s odd higher-order harmonic
distortion, a primary cause of listening fatigue.
Driving low impedance speakers doesn’t necessarily require more watts, but higher current is imperative. We raised
the JC 1+ peak current 33% to 180 amps with the addition of six Sanken 15A/230V/60Mz bipolar output transistors, for
a total of 24. Accommodating six more output devices necessitated changing the output stage circuit board’s
orientation from horizontal to vertical. This added welcome benefits of more effective heat dissipation and easier
serviceability. To conduct higher current flow in the JC 1+ we made the copper traces on its main circuit board and N
and P channel output stage circuit boards twice as thick as on the JC 1.
Supporting this substantial current required an even more
potent power transformer. The massive 2.1 kVA transformer
weighs 30 lb. (13.6 kg) - 30% more than its predecessor.
Developing this power transformer was challenging and
required 11 hand-made samples before we achieved the
necessary power and total absence of mechanical vibration.
The JC 1+ power transformer accomplished this with an
especially potent and expensive steel core.
To unleash greater dynamics, the JC 1+ uses six 33,000uF
Nichicon Gold Tune capacitors, a prodigious total 198,000uF,
compared with four capacitors and 132,000uF in the JC 1. Gold
Tune capacitors are among the finest capacitors ever designed
specifically for high-end audio applications. Although these Gold
Tune capacitors were discontinued years ago, Nichicon
continues to manufacture them exclusively for Parasound.