Усилители мощности моно — Lindemann 858

The 858 is a dual-mono stereo power amplifier from Lindemann, the German electronics maker, built as two fully separate mono amplifiers in one chassis rather than as a monoblock. It belonged to the 800-Series, made in Germany in limited numbers, with a manual dated 2012, and by 2015 it had moved to Lindemann's archive of discontinued products. Its siblings were the 850, 852 and 855 dual-mono power amplifiers, the 830S and 832 control amplifiers, the 885 integrated amplifier and the 825 disc player.

Key specs that matter

Output is 240 W per channel into 8 ohm and 450 W into 4 ohm at below 0.1% THD. Frequency response is 1 Hz to 200 kHz at -3 dB, and voltage gain is 26 dB. The only inputs are one pair of balanced XLR connections, and input sensitivity is 1.87 V for full output into 4 ohm. Output impedance is below 20 mOhm at 100 Hz. Two pairs of WBT speaker terminals accept spades or 4 mm plugs. Consumption is 1,500 W maximum, 80 W at idle and 0.5 W in standby. The amplifier measures 440 x 165 x 345 mm including feet and weighs 27.1 kg.

Engineering and use context

The two amplifiers share only the mains socket, and each has its own 800 W transformer. The signal path is fully balanced for high common-mode rejection. Lindemann describes the circuit as a current-mode amplifier with current feedback, using a single-ended push-pull principle borrowed from valve design, built with few parts, short signal paths, thin-film resistors, film capacitors and highly linear Japanese transistors. Each channel uses 16 power transistors of the thermal-track type, whose on-chip temperature diode sets the quiescent current instantly, arranged as low-inductance H-bridges. The output is bridged, so both speaker terminals are live and the black terminal must never be connected to earth. A speed-controlled fan cools the amplifier, and protection covers DC, overcurrent, overtemperature and mains failure, with an inrush limiter and front LEDs for status. The RJ-45 SYSCOM connection links it to Lindemann's 830 and 832 preamplifiers for automatic switch-on, and a trigger input accepts 5 to 12 V DC.

Pairing

Because of the low input impedance, Lindemann advises against preamplifiers with weak output stages, particularly valve preamplifiers. Solid-state balanced preamplifiers such as the 830S and 832 are the intended partners, and the high power into low impedances drives demanding loudspeakers.

Alternatives

The Lindemann 855 is another dual-mono power amplifier from the same 800-Series.