Усилители мощности стерео — Burmester 911 MK3

The 911 MK3 is a stereo power amplifier from the Top Line of Burmester, the Berlin manufacturer. The MK3 marks the model's third version, and its development drew on work done for the larger 909. Owners of MK1 and MK2 units can have them converted to MK3 by exchanging the output stage boards, and the conversion comes with a new factory warranty.

Key specs that matter

Into 4 ohm the 911 MK3 delivers 2 x 350 W in stereo and 1 x 770 W in mono. The damping factor is 2750, signal to noise ratio exceeds 103 dB and input sensitivity is 770 mV for full output. Frequency response runs from below 10 Hz to 220 kHz at -3 dB. Each channel uses eight selected power transistors, and the power supply combines a 750 VA toroidal transformer with 130,000 µF of filter capacitance. Inputs are balanced, and unbalanced sources connect through supplied adapters in stereo mode only. The speaker binding posts accept spade connectors only. The amplifier measures 482 x 216 x 482 mm and weighs about 31 kg.

Engineering and use context

The MK3 revision brought completely redesigned output stages that run largely in Class A, together with new Burmester SILVER internal wiring, including 8 mm2 pure silver cable from the output boards to the binding posts. The circuit is fully balanced and DC-coupled, with no capacitors in the signal path, and the input stages use Burmester's X-amp modules working in Class A. According to Burmester, the frequency response stays practically independent of the load and the amplifier remains stable into any load. Mono operation is available through external mono adapters or can be set internally at the factory when the amplifier is ordered as a monoblock. External bi-amping adapters allow two 911 MK3 units to drive the bass and upper sections of a speaker separately. The protection circuit sits outside the signal path and watches for overheating, DC offset and overdrive. A trigger input lets Burmester preamplifiers and DACs with variable output switch the amplifier on and off. The housing is silver anodised with an engraved chrome triangle nameplate, and the aluminium heat sinks are pressed by a supplier in Berlin. Every unit is measured by computer, burned in under full load for seven days, measured again and checked in a listening test before shipping.

Pairing

Its high damping factor and power reserve give the 911 MK3 the current for large, low-impedance floorstanding speakers. Burmester's balanced preamplifiers are the intended source, and two units switched to mono form a monoblock pair.

Alternatives

The Burmester 956 MK2 is a lower-powered stereo power amplifier from the same manufacturer.