Luxman M-7i
A high-power stereo amplifier with balanced inputs, low distortion, and an upgrade path from the M-7
Overview
The Luxman M-7i is a stereo power amplifier introduced as an improved version of the M-7, with better circuitry and build quality. It was sold new and also as a factory upgrade from the original M-7 for ¥50,000. It was built during Luxman's post-Alpine era under AZDEN. Output power is high, and the amp can run in stereo or in mono through a BTL connection.
Specifications
| Continuous effective output | Stereo 230W + 230W (4 Ω), 150W + 150W (8 Ω); Monaural 460W (8 Ω) |
| Input sensitivity | 1V/150W (8 Ω), 1V/100W (8 Ω, Reference Position) |
| Input impedance (unbalanced/coaxial) | 45kΩ |
| Input impedance (balanced) | 66kΩ |
| Gain | 32dB |
| Total harmonic distortion | 0.004% (1 kHz, 8 Ω); 0.03% (20 Hz to 20 kHz, 8 Ω) |
| Signal-to-noise ratio | 115 dB (1 kHz, IFF-A) |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| Power consumption | 350W |
| Maximum external dimensions | Width 467 x Height 212 x Depth 440 mm |
| Weight | 26.5 kg |
Design
The M-7i uses Luxman's proprietary CSSC circuit, an all-stage direct-coupled complementary symmetry design. The first stage is a dual FET differential cascode, and the second is a base-mounted current transmission stage. The current amplification stage is a 3-stage Darlington complementary circuit. It drives six large bipolar transistors (Pc = 150W) per channel in push-pull. Luxman's OD beta NFB technology is used, and there is no DC servo amplifier. High DC stability comes from refined bias characteristics instead. The power supply has a high-inertia toroidal transformer and dual 22,000 μF electrolytic capacitors. The inputs have left/right independent attenuators with a 6-contact resistance switching system, and both balanced and RCA inputs are provided. Speaker outputs are custom 3-way terminals that take banana plugs, Y-lugs, and Speakon connectors. There is a logarithmic power meter, internal noise filters for digital interference, and a line phase sensor that detects AC polarity. Custom-made carbon film audio resistors are used throughout. A reference position gives 100W output at 1V input. The M-7i also shares the LUX T-Tag found on early M-7f models. Optional custom builds had solid aluminum top and side panels instead of wood.
Context
The M-7i was part of Luxman's re-launch after the Alpine ownership period, and it was manufactured under AZDEN. It followed the M-7 and was later followed by the M-7f. It kept Luxman's tradition of high-power amplification, with refined circuitry and modular serviceability, including board-level upgrades from earlier models.
Market
The M-7i originally sold for ¥350,000 around 1998. Units upgraded from the M-7 were available for ¥50,000. Custom-order versions with aluminum side panels and altered front anodizing were also offered on request.
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