Parasound Halo JC 3+ User manual

Halo JC 3+ Phono Preamplifier
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A new improved version of our award-winning JC 3
Six years ago we asked legendary audio designer John Curl if he would create a reasonably priced Parasound
Halo phono preamplifier in the spirit of his masterpiece, the Vendetta. Three years later we introduced the
remarkable Parasound Halo JC 3 which has earned rave reviews from the audiophile press and a legion of
vinyl enthusiasts. During the design phase of the original JC 3, Curl had rejected variable load adjustment
because potentiometers generally have higher thermal self-noise, which is an anathema to the creation of
an ultra low noise phono stage. Our decision to bring the JC 3 to market with limited switched input load
impedance choices disappointed some vinyl enthusiasts who consider input load fine-tuning to be essential
for certain cartridges.
Curl and circuit board designer Carl Thompson eventually consented to a redesign with variable load
impedance adjustments, but with these caveats for the potentiometers: 1) They must comply with stringent
performance requirements. 2) They must be manufactured by Vishay, a highly-regarded manufacturer of
low-noise component parts.
We took this opportunity to make additional performance improvements. Curl has narrowed the spectrum
of Johnson/Nyquist noise in the resistor that loads the input stage. Circuit-board designer Carl Thompson
tweaked the phono module board layouts to further optimize every performance parameter. The phono
modules copper circuit board traces now have 24 karat gold-plating where each part is soldered to provide
exceptional transparency and musical detail.
As a result of these changes, the MC signal to noise ratio is improved to 87dB, A-weighted. MM gain has
been increased slightly to 48dB, while MC gain has been lowered from 68dB to 64dB so that extra-high
output MC cartridges won’t cause the JC 3+ to overload the inputs of some line stage preamps or integrated
amps.
The JC 3+ power supply has also been significantly upgraded with 47 percent larger low-ESD power supply
filter capacitors and an 82 percent larger R-core power transformer. This provides much greater current
reserves for head-snapping dynamics. Finally, we added an on/off switch for the front P logo illumination.

Input Sensitivity at 1 kHz
MM: 4mV for 1V output
MC: 600µV for 1V output
Total Gain
MM: 48dB
MC: 64dB
AC Power Requirement
Standby: 1 watt
Power On: 12 watts
115 or 230 VAC 50 - 60 Hz
(Selected on Chassis Bottom)
Dimensions
Width: 17-1/4” (437mm)
Depth: 13-3/4” (350mm)
Height, with feet: 4-1/8” (105mm)
Height, without feet: 3-1/2” (89mm)
Weight
Net: 19 lbs. (8.6 Kg)
Shipping: 26 lbs. (11.8 Kg)
Rack Mount Accessory
HRA 2 (may be purchased separately)
How the JC 3+ improves on the JC 3
- Variable MC load adjust independent for each channel from 50-550 ohms with dual gang
potentiometers specially made for Parasound by Vishay.
- Curl-Thompson tweaked circuits to further reduce the JC 3 silent background noise.
- 24k gold plated copper traces on phono module boards for utmost conductivity and most
transparency/detail in the music.
- 47% larger low ESD power supply filter caps greater reserve for head-snapping dynamics.
- 82% larger R-core power transformer greater reserve for more low end impact.
- Ability to turn off illumination of the front panel P logo.
- Now Available in Silver or Black.
Specifications
Frequency Response
20Hz –20kHz, +/- 0.2dB
Total Harmonic Distortion
< 0.01% at 1kHz
Signal to Noise Ratio, MM
> 87dB, input shorted, IHF A-weighted
> 78dB, input shorted, unweighted
Signal to Noise Ratio, MC
> 87dB, input shorted, IHF A-weighted
> 67dB, input shorted, unweighted
Interchannel Crosstalk
72dB at 1kHz
Input Impedance
MM: 47kΩ
MC: 50 –550Ω variable, 47k Ω fixed
Output Impedance
Unbalanced: < 100Ω
Balanced: < 100Ωper leg
Please note, an original JC 3 cannot be updated to become a JC 3+.
Parasound Products, Inc., 2250 McKinnon Ave., San Francisco, CA 94124 / 415 397-7100
For more photos, features, specifications and product manuals, visit us at www.parasound.com