Интегральные усилители — Line Magnetic LM-84IA

The LM-84IA is a compact integrated valve amplifier from Line Magnetic, built around EL84 output valves in a class AB push-pull circuit. It delivers 12 W RMS per channel and combines a loudspeaker amplifier with a headphone socket and a subwoofer feed in one small chassis. The European price is EUR 1,399 and the US price was USD 1,995, and the box contains the amplifier, an LM-02 remote handset, a detachable mains lead, two spare fuses and the manual.

Key specs that matter

Four EL84 valves form the output stage, two per channel, and the factory hand-selects them before fitting, naming 6P14 and 6BQ5 among the compatible substitutes. Ahead of them sit 12AX7 and 12AU7 small-signal valves, supplied as matched pairs, for which Line Magnetic lists equivalents such as ECC83, E83CC, CV4004, 5751, ECC82, 5814, 6189 and CV4003, along with the 12AX7EH, ECC803 and 12AU7EH types. Frequency response is 20 Hz to 30 kHz within 1.5 dB, THD is 1 percent and the A-weighted noise floor sits 87 dB below full output. The line inputs need 250 mV and the pre-in socket 1000 mV, both into 100 kohm. The case is 360 x 290 x 160 mm and weighs 13.75 kg.

Engineering and use context

Connections on the back cover a CD input and a line input, a pre-in, an RCA line output meant for a powered subwoofer and loudspeaker screw posts that also accept banana plugs. A 3.5 mm headphone jack is fitted, so a pair of headphones can be run from the same valve circuit without a separate amplifier. Volume is handled by a Japanese ALPS potentiometer that responds to the remote. The power supply uses a Z11 core transformer, and the output transformers are EI types of Japanese audio grade. Coupling duties go to Realcap capacitors, and parts are joined by hand with direct point to point leads. A soft start and time-delay circuit waits 30 seconds after switch-on before the amplifier goes live.

Pairing

With its low output the LM-84IA is best matched to efficient loudspeakers, and the 4 ohm and 8 ohm taps let the output transformer suit the nominal load. When small bookshelf speakers run out of bass extension, the line output can drive an active subwoofer. Owners who already have a line stage can connect it to the pre-in socket and use the LM-84IA purely as a power amplifier.

Alternatives

The Line Magnetic LM-34IA is a larger class AB push-pull integrated using EL34 output valves and rated at 40 W per channel.