The desire to have a great phono pre-amplifier for any dedicated audio manufacturer is paramount, and Parasound were no exception to this rule.
Some time ago the legendary audio designer John Curl was asked by Parasound if he would create a reasonably priced Halo phono pre-amplifier in the spirit of his masterpiece, the Vendetta (Research). Three years later they introduced the remarkable Parasound Halo JC 3 - which then 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.
The 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. The first consideration was that they must comply with stringent performance requirements, and the second key factor was that they must be manufactured by Vishay, a highly-regarded manufacturer of low-noise component parts.
Curl and Thompson 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. The JC 3+ was born.
As a result of these changes, the MC signal to noise ratio is improved to 87dB, A-weighted. MM gain has been increased 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.
- Inputs and outputs use Vampire brand 24k gold-plated RCA jacks
- Balanced outputs use Neutrik brand premium XLR jacks
- Exclusively Vishay-Dale resistors in the audio path
- Triple shielding; low-carbon mild steel partitions isolate the power supplies & AC wires
- Dual mono design; each audio channel is separately enclosed in its own extruded aluminum enclosure
- Separate high speed-soft recovery rectifiers, filter caps and voltage regulators for each channel
- Superior R-core type power transformer
- Mono switch can improve sound of mono and older LPs
- Built-in AC line conditioner to prevent AC noise from polluting the circuits
- AC polarity reverse switch can reduce hum in many systems
- Non-magnetic aluminum rear panel for purest sound
- Turn On Options switch: manual or auto with 12v trigger input
20 Hz - 20 kHz, +/- 0.2 dB
Total Harmonic Distortion:
< 0.01% at 1 kHz
Signal to Noise Ratio, MM:
> 87 dB, input shorted, IHF A-weighted
> 78 dB, input shorted, unweighted
Signal to Noise Ratio, MC:
> 87 dB, input shorted, IHF A-weighted
> 67 dB, input shorted, unweighted
72 dB at 1 kHz
MM: 47k Ω
MC: 50 - 550 Ω variable, 47k Ω fixed
Unbalanced: < 100 Ω
Balanced: < 100 Ω per leg
Input Sensitivity at 1 kHz:
MM: 4mV for 1 V output
MC: 600ÂµV for 1 V output
MM: 48 dB
MC: 64 dB
XLR Pin Identification:
1 = Ground (Shield)
2 = Positive
3 = Negative (Return)
AC Power Requirement:
Standby: 1 watt
Power On: 12 watts
115 or 230 VAC 50 - 60 Hz
(Selected on Chassis Bottom)
Width: 17-1/4" (437mm)
Depth: 13-3/4" (350mm)
Height, with feet: 4-1/8" (105mm)
Height, without feet: 3-1/2" (89mm)
Net: 19 lbs. (8.6 Kg)
Shipping: 26 lbs. (11.8 Kg)
Rack Mount Accessory:
HRA 2 (may be purchased separately)
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