Усилители мощности стерео — Krell Chorus 5200 XD

The Chorus 5200 XD is a Krell five-channel power amplifier that applies the company's Class A iBias technology in its XD version to a multichannel chassis intended for 5.1 home theatre systems. The XD revision reduced output impedance compared with the earlier Chorus 5200.

Key specs that matter

All five channels are rated, with every channel driven, at 200 W RMS into 8 ohm and 360 W RMS into 4 ohm, with 113 V peak to peak or 40 V RMS of output voltage and 13.4 A of peak current. Gain is 26.2 dB and input sensitivity is 1.96 V RMS for single-ended or balanced connection, with input impedance of 100 kohm on RCA and 200 kohm on XLR. Response stays flat within 0.08 dB from 20 Hz to 20 kHz and extends from 0.5 Hz to 100 kHz at the 3 dB points. Distortion is below 0.04% at 1 kHz and 200 W into 8 ohm and below 0.15% at 20 kHz. Noise sits more than 95 dB below full output wideband unweighted and more than 115 dB below with A-weighting. Output impedance is under 0.015 ohm from 20 Hz to 20 kHz, damping factor exceeds 530 and slew rate is 40 V per microsecond.

Engineering and use context

The iBias circuit senses the current drawn by each speaker and adjusts the bias of its output transistors accordingly, keeping the transistors in Class A without the constant heat load of a fixed high bias. Consumption is 1 W in standby, 182 W at idle and up to 2100 W, with heat output of 623 BTU per hour at idle and 7182 BTU per hour at maximum. Quiet thermostatically controlled fans handle cooling inside a chassis 434 mm wide, 194 mm high and 536 mm deep that weighs 38.6 kg alone or 43.2 kg shipped. An RJ45 Ethernet port allows remote monitoring of the amplifier over the internet and from mobile devices, which helps in rack installations. Each channel has its own RCA and XLR input, giving five of each, and five pairs of binding posts on the rear panel.

Pairing

The amplifier is meant to sit after a surround processor or multichannel preamplifier with balanced outputs, feeding the three front speakers and the pair of surrounds. Most processors can drive it without extra gain. For 7.1 layouts a second amplifier is needed for the extra channels, and the high maximum draw calls for a dedicated mains circuit in a crowded rack.

Alternatives

The Krell Duo 300 XD belongs to the same XD range as a two-channel amplifier, rated at 300 W per channel into 8 ohm and 540 W into 4 ohm.