Напольная акустика — Line Magnetic LM-3

The LM-3 is a three-way horn loudspeaker system from Line Magnetic Audio, the Chinese company whose work on classic Western Electric equipment shapes much of its catalogue. The LM-3 follows the design concept of the Western Electric horn systems and is offered in two versions - one with Alnico permanent magnet drivers and one with field coil drivers that draw their magnetism from an external supply. Both share the same horn and crossover layout and the same large cabinet.

Key specs that matter

For the LM-3 the company lists 38 Hz to 20 kHz, with a sensitivity of 105 dB and a nominal impedance of 16 ohm. The power figure quoted for the system is 100 W. The cabinet measures 900 mm wide, 2,080 mm high and 690 mm deep, so the speaker stands a little over two metres tall. In the Alnico version the tweeter is the LM-302, a cobalt tweeter that the company describes as a Jensen replication, the midrange is a 22A horn driven by a 555 compression driver with an Alnico magnet, while low frequencies go to a BA-18 Alnico woofer.

Engineering and use context

The field coil version swaps in different drivers at each end of the band. High frequencies go to the HT-70CU, a copper and aluminium horn tweeter with a field coil motor, the midrange keeps the 22A horn but with a field coil 555, and the low end uses the TA-4181, an 18 inch field coil woofer that Line Magnetic presents as a recreation of a vintage Western Electric unit, developed with modern digital engineering and material analysis of original drivers. Both versions divide the signal through the same TA-7376 crossover. A field coil driver uses a DC powered electromagnet as its motor instead of a permanent magnet, so this version ships with the PR-22 three-way excitation supply. The PR-22 is an adjustable unit with a vacuum tube rectifier, built around the WE4144 circuit with some Western Electric materials, and it uses four EL-6C tubes. It offers three outputs - LOW at DC 10 to 24 V and MID and HIGH at DC 3 to 10 V, each at 0.5 to 2 A - with a pointer meter for setting the current. The supply measures 485 x 320 x 450 mm, weighs 39 kg and accepts either 220 to 240 V or 100 to 120 V mains.

Pairing

Line Magnetic builds tube amplifiers alongside its horn systems, including the LM-300IA with 300B output tubes in single-ended form, and the LM-212 Premium, which drives 212 triodes and provides output taps matching the nominal load of the LM-3.

Alternatives

The Line Magnetic LM-812 is another floorstanding horn speaker system in the company's loudspeaker range.