Усилители мощности стерео — Proficient Audio PAS-A4100

The PAS-A4100 is a four-channel analog filtering amplifier from Proficient Audio, a brand owned by Nice North America, aimed at distributed audio and home entertainment installations. It fits in a single rack-mount chassis and is sold with rack ears and tabletop feet, so it can go into an equipment rack or onto a shelf. It has four independent channels that can be bridged in pairs.

Key specs that matter

Proficient quotes up to 100 W per channel into 8 ohm with all channels driven, and a rated continuous output of 70 W per channel. Into 4 ohm the power almost doubles. Bridging gives three layouts into 8 ohm - 2 x 200 W, 2 x 100 W plus 1 x 200 W, or 4 x 100 W. Each channel can carry up to three 8 ohm speakers. Gain is 30 dB, frequency response at 1 W is 20 Hz to 20 kHz, THD+N is 0.05% and signal-to-noise reaches 98 dB. Crosstalk is 80 dB at 1 kHz and 70 dB at 10 kHz, and residual noise is 0.3 mV. The chassis is 292 x 432 x 38 mm, and runs on 100 to 120 V or 220 to 240 V mains at 50 or 60 Hz with a maximum draw of 400 W.

Engineering and use context

Instead of DSP, every channel has a three-position switch for low-pass, full-range or high-pass operation, with high-pass points of 20 Hz or 100 Hz. This lets one amplifier feed small satellite speakers and a passive subwoofer at once without a separate processor or network setup. Rear dials adjust the input level of each channel independently, either to match sources or to cap the maximum volume for small speakers. The amplifier stays stable at low impedance, so a channel can drive several satellites or one subwoofer. Three turn-on modes are offered - audio signal sensing with a 5 mV threshold, always on, or trigger voltage. The trigger input on a 3.5 mm jack accepts 3 to 24 V AC or DC at 20 mA, and a 12 V DC trigger output supplies up to 150 mA to the next device. The design has no fan. On the brushed aluminium front panel each channel has an indicator that turns green with signal and red when clipping, and a status LED shows blue in normal use and red when the protection circuit has tripped.

Pairing

Gold-plated stereo inputs are joined by RCA cascade outputs on every channel, which can be patched to a neighbouring channel or sent on to another device. Speakers connect through five-way binding posts.

Alternatives

The Proficient M2 is a two-channel stereo power amplifier from the same brand, rated at 125 W per channel into 8 ohm and 235 W into 4 ohm.