Усилители мощности моно — Parasound JCM250

The JCM250 is a compact monoblock power amplifier from Parasound with circuitry by John Curl, sold as a single unit at USD 4,250 and housed in a 2U rack-width chassis. Two are required for stereo, and Parasound gives a warranty of three years on parts and labor.

Key specs that matter

Rated power is 250 W into 8 ohm, 450 W into 4 ohm and 800 W into 2 ohm, RMS continuous from 20 Hz to 20 kHz at 0.15 percent THD with a 120 VAC supply. Class A output reaches 8 W with high bias selected and 4 W with low bias. Peak current capacity is 100 A and slew rate exceeds 130 V per microsecond. Frequency response is 2 Hz to 110 kHz within +0/-2 dB and 20 Hz to 20 kHz within +0/-0.25 dB. THD is under 0.15 percent at full power and falls under 0.02 percent in normal use. IM distortion is under 0.03 percent, and Parasound gives TIM as unmeasurable. IHF A-weighted noise is more than 120 dB down at low bias and more than 118 dB down at high bias. Input impedance is 50 kohm unbalanced and 100 kohm balanced, or 50 kohm per leg, and gain can be set to 29 dB or 23 dB. The case is 437 mm wide, 89 mm high without feet or 105 mm with them, and 508 mm deep, growing to 546 mm with cables attached. It weighs 19.1 kg, or 22.7 kg for shipping.

Engineering and use context

There are no capacitors or inductors in the direct-coupled audio chain, which begins with a JFET input circuit followed by MOSFET drivers. The output stage uses 16 beta-matched transistors rated at 15 A, 230 V and 60 MHz, and the input and driver stages have independent power supplies. Bybee Music Rails filters are applied to the input stage. Parasound states the amplifier is stable with impedance dips below 1 ohm and rates full power down to 2 Hz. Harris soft-recovery bridge diodes, REL and Nichicon Muse capacitors, DC servo and relay protection and AC inrush surge protection complete the design. Consumption is under 1 W in standby, 125 W or 240 W at idle depending on bias, 300 W typical and 800 W maximum.

Pairing

XLR and RCA inputs each have a loop output, which makes bi-amping from one preamp feed simple, and the 2U height lets the amplifier fit a standard equipment rack. CHK Infinium 5-way binding posts support bi-wiring. Turn-on works from a 12 V trigger at 9 to 12 Vdc or by audio sensing from 2.5 to 10 mV.

Alternatives

The Parasound JC1+ is the larger monoblock in the range, rated at 450 W into 8 ohm and 850 W into 4 ohm.