Усилители мощности моно — Parasound JCA100

The JCA100 is a single-channel Parasound power amp running in Class A, issued as the John Curl Tribute Edition in honour of the designer long associated with the company. Curl is credited with the design, production is limited to 100 pairs hand-built on American soil, and it is sold only as a matched pair at USD 25,000. Warranty cover lasts three years, and each unit carries its own serial number on both faceplate and chassis.

Key specs that matter

Each monoblock produces 100 W into 8 ohm in pure Class A and up to 200 W into 4 ohm. Input sensitivity is 1 V on RCA and 1 V per leg on XLR, with input impedance of 50k ohm unbalanced and 100k ohm balanced. Gain is switchable between 29 dB and 23 dB. THD stays under 0.15% at full power and under 0.02% at normal volume, intermodulation stays below 0.03%, and slew rate exceeds 130 V per microsecond. Response is 20 Hz to 20 kHz within 0.25 dB and 2 Hz to 120 kHz within 2 dB. A-weighted signal-to-noise is over 120 dB with low bias and over 118 dB with normal bias. Idle draw is 205 W in low bias and 230 W in normal bias, peaking at 250 W, with under 1 W in standby. Each chassis is about 447 mm wide, 197 mm tall and 508 mm deep, and weighs 37.6 kg.

Engineering and use context

A rear Bias Level switch sets the output transistors either for full Class A or for a lower idle current that turns the stage into Class AB, so the amp runs cooler. Parasound suggests the low position when the heatsinks cannot be touched for five seconds, when the amp sits in a cabinet or unventilated rack, or when room temperature passes 28 C. A separate selector optimises noise for balanced or unbalanced use, and XLR and RCA pass-through outputs carry the input signal onward for bi-amping or a powered subwoofer. Switch-on can be handled in three ways - manual, audio sensing with shutdown after about 8 to 10 minutes of silence, and an opto-coupled 12 V trigger drawing 5 mA, with a loop-out jack. A delay knob staggers power-up by up to 12 seconds, and protection circuits react to overheating, too low a load or a shorted cable. Rack brackets come in the box.

Pairing

The binding posts take banana plugs, spades up to 16 mm wide or bare wire up to 8 AWG. Parasound recommends the lower gain position for loudspeakers above 96 dB sensitivity or when the preamp volume rises too quickly, and balanced cables give 6 dB more level than the RCA inputs. With output doubling as the load impedance halves, the pair suits passive speakers with low nominal impedance.

Alternatives

The Parasound Halo JC 1+ is a monoblock rated at 450 W and 850 W into the same two loads, running in pure Class A up to 25 W before moving to Class AB.