Pre/Power Amplifiers

Although the JC5 is a 'power amplifier', its two gain controls and RCA line outputs also allow the signal to be intercepted between the 'high voltage' J-FET input stage and the MOSFET/bipolar output stage proper. At full 'volume' the gain potentiometers are still not precisely matched and so our sample had a 0.3dB channel imbalance (28.63dB and 28.95dB gain via balanced inputs). Moreover the internal layout of the JC5 is not precisely dual-mono so there is a slight difference in noise and achievable A-wtd S/N ratio between left and right channels – 89.4dB and 87.3dB, respectively, re. 0dBW. Otherwise the JC5 is exactly what we might expect – a rugged and low distortion powerhouse that's more than a match for competing sub-£10k heavyweights.

Parasound claims Class A operation up to 12W/8ohm for the JC5. In practice its substantial 208W idle power consumption and 42oC heatsink temperature would not lead me to question this specification. The 2x400W/8ohm power rating is only achieved by the skin of its transistors, however, with a full 240V AC mains voltage [see Sidebar]. On the other hand, its 600W/4ohm spec. is substantially bettered at 2x700W/4ohm while the huge PSU supports 515W, 960W, 1680W and 1180W into 8, 4, 2 and 1ohm loads under dynamic conditions at <1% THD [see Graph 1]. Distortion is generally within Parasound's loose 0.05% rating at 0.001%/1W, 0.003%/10W and 0.0075%/100W through bass and midrange, increasing to 0.055%/20kHz at 10W/8ohm [see Graph 2]. Meanwhile the JC5's output impedance is a low ~0.02ohm through the audio range and its frequency response an extended 1Hz-48kHz (±1dB). PM

Power output (<1% THD, 8/4ohm): 405W / 700W
Dynamic power (<1% THD, 8/4/2/1ohm): 515W / 960W / 1680W / 1180W
Output imp. (20Hz–20kHz/100kHz): 0.022–0.040ohm / 0.177ohm
Freq. resp. (20Hz–20kHz/100kHz): +0.01dB to –0.23dB/–3.1dB
Input sensitivity (for 0dBW/400W): 105mV / 2100mV (balanced)
A-wtd S/N ratio (re. 0dBW/400W): 89.7dB / 115.7dB
Distortion (20Hz-20kHz, 10W/8ohm): 0.0015–0.055%
Power consumption (Idle/Rated o/p): 208W / 1.26kW
Dimensions (WHD) / Weight: 448x197x508mm / 33.1kg
Price: £6999