Parasound JC1+ Mono Power Amplifier

One channel to rule them all

Parasound's monolithic 83-pound JC 1+ can kick out the jams with absolute authority. It delivers a whopping 450 watts into a single channel at 8 ohms, and it's stable down to 2 ohms, offering flexibility to drive even the most demanding speakers.

The company's famed audio guru John Curl spent five years developing this amp as an upgrade to his original JC 1, which has been wowing audiophiles since 2003. He redesigned the input stages with an independent power supply for increased output with minimal distortion.

Internal view of Parasound JC 1+ monoblock power amplifier
Parasound's audio guru John Curl chose the parts for the JC 1+ and laid out its circuit pathways to ensure high power with minimal distortion.

Class A/AB operation for smoother sound

The JC 1+ uses Class A/AB amplifier technology, which we don't see every day. So let's talk about what that means.

Engineers and audiophiles generally agree that Class A designs offer the purest sound, but they tend to run hot and take up a lot of space. As a result, home audio amplifiers often use a compromise known as Class AB, which hands off part of the audio signal to a different set of output transistors at high power levels. AB can sacrifice a bit of signal purity, but it lets the amp run cooler and more efficiently.

So this Class A/AB amp operates in pure Class A mode up to a higher power level than most other amplifiers in its price category, before the second set of transistors kick in. The result is a sound that's smoother, less fatiguing, and more natural. This amp includes a bias switch that can be set to "low" to reduce heat output and power consumption. When it's set to "high," the amplifier delivers up to 25 watts of pure Class A power.

Convenient connections

On the back panel are single balanced mono XLR and unbalanced mono RCA input and output with switchable gain. There are also a pair of speaker binding posts, with the second pair allowing easy bi-wiring. The amp can be rack mounted using the included ears.

The legacy of John Curl

As noted above, the JC 1+ was designed by audio engineering mastermind John Curl — his signature appears on the front and back panels, as a matter of fact. Curl started his career in the 1970s, designing tape and video recorders at Ampex, and he had a hand in building the Grateful Dead's famous Wall of Sound. He has worked with Parasound since 1989, designing all of their high-power amplifiers and more. He chose this flagship amp's parts and laid out its circuit pathways to deliver no-holds-barred power and performance for audiophiles.

Product highlights:

• 450 watts into a single channel at 8 ohms (20-20,000 Hz) at 0.15% THD
  
• 850 watts x 1 at 4 ohms
  
• 1,300 watts x 1 at 2 ohms
  
• designed by legendary audio engineer John Curl
  
• Class A/AB amplifier design with Normal/Low bias switch
  
• rated for up to 25 watts of pure Class A power in Normal mode
  
• Low setting reduces heat output and power consumption
  
• large custom toroidal transformer
  
• separate R-core power transformer for input stage
  
• Bybee Music Rails™ filter high frequency noise from the input stage
  
• frequency response: 2-120,000 Hz (+0/-2dB)
  
• signal-to-noise ratio: 122 dB (bias set to Low)
  
• balanced XLR and unbalanced RCA input and output
  
• switchable gain: Low +23 dB; Normal +29 dB
  
• dual binding post speaker connectors enable bi-wiring of a single speaker
  
• switchable turn-on options: manual, signal sensing, or 12-volt trigger
  
• selectable turn-on delay (0, 4, 8 or 12 seconds)
  
• detachable power cord
  
• rack mounting ears included
  

Dimensions and warranty:

• 17-5/8"W x 7-3/4"H x 21-1/2"D (4U rack spaces)
  
• weight: 83 lbs.
  
• warranty: 5 years
  
• Our 60-day money-back guarantee
  
• MFR # JC 1 + BLACK
  

What's in the box:

• Parasound JC 1+ owner's manual
  
• Mono power amplifier
  
• 6' AC power cord
  
• 6' Mono-minijack cable
  
• Rack-mount hardware
  
• Owner's Guide
  

Features & specs

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Features

Mono Power Amplifier: The Parasound HALO Series JC 1+ is an ultra-high performance Class A/AB, mono power amplifier. The JC 1+ is built to extremely strict quality and performance standards for which Parasound is renowned. Every part within the JC 1+ has been carefully chosen for its accuracy, sound quality and long life. The Halo Series JC 1+ mono amplifier is profoundly powerful and supremely musical. The JC 1+ mono power amp can handle 8, 4, and 2 ohm loads.

• 400 to 450 Watts @ 20-20kHz with 0.15% THD
• 800 to 850 Watts @ 20-20kHz with 0.15% THD
• 1200 to 1300 Watts @ 20-20kHz with 0.15% THD

Class A/AB Operation: Pure class A operation provides the purest sound. However, an amplifier with the output power of the JC 1+ and operating entirely in class A would be enormous, highly inefficient, and generate far too much heat. Class A/B combines the primary advantage of Class A with the higher efficiency of Class B. This reduces the heat generated in pure class A operation as well as the higher-order odd harmonic distortions created in class B. In class AB, the driver and output stages are always partially turned on, which provides a nominal amount of pure class A operation. At higher power levels, when the musical waveform swings from positive to negative and vice versa, each bank of transistors is allowed to rest momentarily. This resting makes it possible to deliver high amounts of power without overheating. It also makes possible the use of passive cooling and avoids fans, whose noise can be heard over the music. The result is less fatiguing, more natural sound.

Independent Power Supplies: The Parasound HALO Series JC 1+ mono power amp utilizes independent power supplies for the input and output stage for robust, clean power.

• Input Stage Power Supply: To prevent any distortion originating in the input stage, the JC 1+ has an independent input stage power supply with its own R-core power transformer. The 110V B+ and B- voltage rails cannot sag under any condition, virtually eliminating distortion, regardless of how hard the output stage is working. The independent driver power supply for the input stage employs premium Nichicon Gold capacitors totaling 4,440uF per channel. The JC 1+ input stage power supply also employs two Bybee Music Rails. These are sophisticated active filters that "scrub" the last vestige of high frequency noise from the input stage.
  
• Output Stage Power Supply: The heart of the output stage power supply is a 2.1kVA toroid power transformer with a special premium grade steel core chosen for its efficiency, low hum field, and high continuous power rating. Encapsulating this massive power transformer in a steel canister filled with epoxy prevents mechanical vibrations, assuring ultra-quiet performance. The JC 1+ output stage also includes six ultra-premium quality 33,000uF Nichicon "Gold Tune" electrolytic filter capacitors. These rare parts are chosen for their low Equivalent Series Resistance (ESR), dielectric absorption and resistance to high temperature. In addition, these filter capacitors are bypassed with smaller polypropylene capacitors to reduce AC ripple in the DC supply and to further eliminate noise and interference that is generated in AC power lines, from computers and other appliances in the home.
  

Complementary Differential Configuration: Each stage (Input, Driver, and Output) of amplification employs transistors that require positive DC power and complementary transistors that require negative DC power that is a mirror image of the positive DC power. Thus, half of the transistors amplify the positive half of the musical waveform while the other half of the transistors amplify the negative half. This complementary topology is inherently linear, which minimizes distortion and improves sonic accuracy.

• Input Stage: The function of the JC 1+'s input stage is voltage gain. It uses matched pairs of N and P channel discrete JFETs (Junction Field Effect Transistors) arranged in a differential configuration. JFETs are ideal for the input stage because their inherently high impedance makes them less affected by the impedance of the connected source components. Ordinary bi-polar transistors are low impedance devices and more susceptible to the higher impedance of source components. The Differential configuration also provides superior noise reduction. These precision matched input JFETs are cascaded to produce the current necessary to drive the MOSFET drivers in the following stage.
  
• Driver Stage: The driver stage provides further voltage gain for which we employ a complementary matched pair of MOSFETs (Metallic Oxide Field Effect Transistors) selected for their vacuum tube-like sonic qualities. MOSFETs tend to generate less odd-order higher harmonic distortion than bipolar transistors. This is important because odd-order distortion sounds unnatural and fatiguing to the human ear because the harmonics are dissonant. Even-order distortion is less offensive because it is primarily consonant. The JC 1+ employs a driver stage in a new cascade configuration which improves linearity and reduces distortion. This sophisticated MOSFET driver stage prevents the harshness and brittle sound so often found in other solid state amplifiers.
  
• Output Stage: An amplifier's sonic characteristics are established by its input and driver voltage gain stages. The sole job of its output stage is to deliver current from its power supply to the speakers. In the output stage bipolar output transistors are superior to MOSFETs because of their higher safe operating area (SOA) and inherent ruggedness. The JC 1+ employs 24 high current (15-amp) high voltage bipolar transistors to insure long-term reliability, even with continuous high-power operation and challenging speaker loads. The lightning-fast (60 MHz) transistors respond instantly to complex demands in the musical signal, virtually eliminating distortions that occur with “slower” transistors. Slew rate limiting and Transient Intermodulation Distortion (TIM) are simply not an issue in the JC 1+
  

Balanced & Unbalanced Analog Inputs: The Parasound HALO Series JC 1+ mono power amplifier features balanced XLR and unbalanced RCA connectivity, including its inputs and outputs.

• Mono Audio Inputs: The Parasound HALO Series JC 1+ is outfitted with both balanced XLR and unbalanced RCA analog inputs. In most systems balanced XLR connections will give you the best sound. Using balanced XLR input connectors results in a 6 dB higher volume level compared with using the RCA input jacks.
  
• Loop Output Jacks: The JC 1+ is equipped with a balanced XLR and unbalanced RCA output that enable the incoming audio signal to pass along or "daisy-chain" from the Left and Right Input jacks to an additional amplifier or powered subwoofer. The XLR input signal is available at both the XLR and RCA output jack, while the RCA input signal is only available at the RCA output jack. The Loop Out jacks are not affected by the Gain control settings.
  

Note: The Balanced/Unbalanced switch is not an input selector. Its function is to optimize the signal to noise ratio for each type of input. You should not connect both the Balanced and Unbalanced jacks at the same time with the expectation of switching between two different devices such as a preamp and surround processor.

Controls: The HALO Series JC 1+ mono power amp features a Bias Level and Gain Switch on the rear-panel.

• Bias Level: The Bias Level switch offers two bias settings for the output transistors. In its Normal (up) switch position, bias idle current is higher to perfectly match the characteristics of the JC 1+’s output devices. In its Low (down) position, bias idle current and class A operation are lowered to reduce heat output and power consumption.
  
• Gain Switch: The Gain switch has two positions Low (23dB) and Normal (29dB). This switch would typically be left in the Normal position. If you have very high sensitivity speakers or your preamp already has very high gain then you should use the Low setting.
  

24K Gold-Plated Binding Posts: The Halo Series JC 1+'s speaker terminals are new, developed in collaboration with CHK. Their ample size and wide spacing accommodates even the largest gauge speaker wire, spade connector, and banana plugs (single only). High quality 24 K gold-plating on the speaker terminals, input connectors and internal audio signal connections assure sound quality that won't be compromised by corrosion.

Detachable AC Power Cord: The AC cord supplied with the JC 1+ is a high quality IEC type cord. Please connect it directly to an AC wall outlet or power conditioner that is always on. If possible, plug your JC 1+ into the same AC outlet that your preamplifier is plugged into. If different AC outlets are used for the JC 1+ and other components, (including a TV or video projector) the ground potential may be higher or lower between the outlets, resulting in audible hum.

Turn-On Options: The Turn On Options switch on the back-panel determines how the amplifier turns on and off. Setting the Turn On Options switch to Audio or 12 V disables the JC 1+'s front-panel Power button. There are 3 positions for this switch - Manual, Audio, or 12V Trigger.

• Manual: When the Turn On Options switch is set to Manual, the JC 1+ is turned on and off manually only by pressing the Power button on its front-panel every time you want to listen to music.
  
• Audio: When the Turn On Options switch is set to the Audio position, the JC 1+ will be turned on automatically when an audio signal is present at the L or R Input jacks. After the audio signal ceases the amplifier will remain on for about 10 minutes before shutting itself off. This prevents unintended turn-off during pauses in your music.
  
• 12V Trigger: When the Turn On Options switch is set to its 12V position, the JC 1+ is turned on and off only with an external +9 V to +12V DC voltage, using its 12V Trigger input (3.5mm). When the external voltage ceases the amp will turn off within a few seconds. The 12V turn on trigger circuit in the JC 1+ requires a mere 5mA from the 12V trigger source.
  

12V Loop Out Jack: The 12V Trigger Out jack (3.5mm) lets you loop or "daisy-chain" the incoming trigger voltage to an additional JC 1+ or other component(s). The total load on your triggering device's 12V output is the sum of the trigger current drawn by each of the components you plan to loop together. Check the maximum capacity of your preamplifier's trigger output so you do not overload it by connecting too many power amplifiers. Typical triggering devices are rated to handle 50mA to 100mA.

Rack Mountable: The JC 1+ features a 4 rack space chassis with rear carry handles. Rack mounting hardware is included.

High-Temp Indicator: The front-panel High-Temp indicator will glow red if any channel overheats. The On-Off button will also glow red if the JC 1+ overheats. If such a condition occurs you must provide for better ventilation around the amplifier or check speakers for faulty operation that is causing the JC 1+ to overheat.