Интегральные усилители — Line Magnetic LM-845 Premium

The LM-845 Premium is a two-chassis valve integrated amplifier from Line Magnetic, a company that designs and builds its products in China. Each channel uses one 845 valve in a single-ended class A output stage rated at 30 W RMS, and the amplifier is split into a main electronics unit and a separate unit carrying the output transformers. The European list price is EUR 8,999, while the Australian price was AUD 11,999.

Key specs that matter

Signal passes from a pair of 12AX7 input valves through two 310A and two 300B driver valves to the pair of 845 output triodes. Line Magnetic quotes 1 percent THD at 1 kHz, an A-weighted signal to noise figure of 87 dB and a response from 10 Hz to 50 kHz at minus 1.5 dB. In integrated mode sensitivity is 220 mV, and the inputs present 100 kohm. The rear panel carries three RCA line inputs in pairs plus a pre-in socket, with screw loudspeaker terminals that also take banana plugs. The main unit measures 435 x 460 x 456 mm and the output unit 435 x 160 x 456 mm, giving 435 x 620 x 456 mm when stacked, and the two parts together weigh 62 kg.

Engineering and use context

No fewer than eight transformers handle power supply, filtering, coupling and output duties. The mains transformers are EI types wound on a Z11 core, and the two output transformers are wide-bandwidth EI parts of Japanese audio grade. The second enclosure is given over entirely to that output iron. Two bias controls, one for the 300B drivers and one for the 845s, let the owner set operating current, and two meters on the front plate show the readings. A front-panel switch chooses between two levels of negative feedback. Volume goes through an ALPS potentiometer from Japan, the parts list includes Realcap capacitors plus MIT and Mundorf MCap coupling capacitors, and every joint in the signal path is made by hand with point to point leads. An aluminium remote handset is part of the package.

Pairing

With its single-ended output stage, loudspeakers of reasonable efficiency make the best partners, and taps for 4, 8 and 16 ohm allow each speaker's nominal impedance to be met on the right winding. Through the pre-in socket the LM-845 Premium can also run as a pure power amplifier fed by an outboard preamplifier, which suits owners who already have a valve line stage they want to keep.

Alternatives

The Line Magnetic LM-845IA is a smaller single-chassis integrated built around the same single-ended 845 output valve, rated at 22 W per channel.