Усилители мощности стерео — Arcam PA720

The PA720 is a seven-channel power amplifier in the HDA range from Arcam, a brand owned by HARMAN International. It uses Class G amplification with the first 20 W of output running in Class A, and it is aimed at home cinema installations and at any system that needs more than two amplified channels.

Key specs that matter

Arcam rates continuous output at 0.2% THD per channel in three ways. With all seven channels driven across 20 Hz to 20 kHz the figure is 100 W into 8 ohm and 140 W into 4 ohm, and the headline 7 x 140 W on the feature list refers to that 4 ohm case. With five channels driven at 1 kHz it rises to 110 W into 8 ohm and 175 W into 4 ohm, and with two channels driven at 1 kHz it reaches 140 W into 8 ohm and 225 W into 4 ohm. Harmonic distortion is 0.002% at 80% power into 8 ohm at 1 kHz. Input sensitivity for 50 W into 8 ohm is 800 mV RMS on RCA and 1.6 V RMS on XLR, input impedance is 10 kohm, and at that same 50 W reference Arcam quotes an A-weighted noise ratio of 105 dB. Frequency response is 20 Hz to 20 kHz within 0.05 dB. Measured with feet, control knob and speaker terminals the case is 433 x 425 x 177 mm, with a net weight of 18 kg and 19.7 kg packed.

Engineering and use context

Power is drawn through a toroidal transformer, and the output stages use paralleled transistors inside an acoustically damped chassis. Each input can be switched between unbalanced RCA and balanced XLR. Ethernet and RS232 ports allow control from home automation and third-party systems. The mains section accepts 110 to 120 V or 220 to 240 V at 50 to 60 Hz. Maximum consumption is 1.5 kW, while typical idle draw is 90 W, which Arcam equates to thermal dissipation of about 340 BTU per hour, and standby consumption stays under 0.5 W.

Pairing

With XLR and RCA sockets on each of its inputs, the amplifier takes pre-outs from an AV processor of either type, and seven channels are enough for a 7.1 or 5.1.2 speaker layout without a second amplifier.

Alternatives

The Arcam PA240 from the same HDA range is a two-channel Class G power amplifier offering stereo, dual mono and bridged operation.