Luxman L 309 (1973–1975)
An integrated amplifier introducing Luxman’s Linear Equalizer, succeeded by the improved L-309V in 1975.
Overview
The Luxman L-309 is an integrated amplifier released in September 1973, positioned as a mid-to-high-end model following the L-308. It introduced Luxman’s signature Linear Equalizer—a 5-step tilt filter adjusting the RIAA curve around 1 kHz—offering fine control over record playback tonality. The L-309V, released in October 1975, was an updated version in Luxman’s 50th-anniversary "V" series, featuring relocated phono input impedance controls, a muting switch, and upgraded speaker terminals. The L-309 and L-309V share core circuit design, including a fully complementary DC power amp section with dual-rail power supply and a 3-stage DC equalizer for phono.
Specifications
| Production years | 1973 (L-309), 1975 (L-309V) |
| Original price | ¥120,000 (L-309, 1973), ¥148,000 (L-309V, 1975) |
| Continuous effective output | 80W + 80W (8 Ω, both channels, 20 Hz–20 kHz) |
| Total harmonic distortion | 0.03% or less (8 Ω, 80W) |
| Output bandwidth | 5 Hz – 40 kHz (-3dB, 0.1%) |
| Signal-to-noise ratio (Phono) | 62 dB or more |
| Signal-to-noise ratio (Tuner/Aux) | 80 dB or more |
| Damping factor | 40 (8 Ω load) |
| Input sensitivity / impedance (Phono1) | 2.5mV / 30k–50k–100k Ω (continuously variable) |
| Input sensitivity / impedance (Phono2) | 2.5mV / 50k Ω |
| Input sensitivity / impedance (Tuner) | 150mV / 40k Ω |
| Input sensitivity / impedance (Aux1/2) | 150mV / 50k Ω |
| Residual noise | 0.5 mV or less |
| Power consumption | 300W (at rated output) |
| External dimensions | 485 mm W × 165 mm H × 300 mm D |
| Weight | 15.5 kg (L-309V) |
| Semiconductors | Transistors: 47, ICs: 1, Diodes: 20, Zener diodes: 4, Varistors: 6 |
Design
The L-309V uses a fully complementary OCL power amplifier circuit with a split power supply and two-stage differential amplification, directly coupled throughout. The output stage operates in class B, preceded by a class A predrive stage with an emitter follower buffer. The preamp section features a 2-stage direct-coupled intermediate amplifier and a LUX System NF-type tone control with selectable turnover frequencies (150 Hz, 300 Hz, 600 Hz for bass; 1.5 kHz, 3 kHz, 6 kHz for treble). The phono equalizer uses an RC4558 op-amp and includes a push-pull output stage in an inverted Darlington configuration operating in class A. The power supply is fully separated for the preamp, driver, and output stages, with two 15,000 μF capacitors filtering the output stage. The L-309V shares the same transformer, PB642 equalizer filter switch, and PB1024 protection/power board as the L-85V, though its protection circuit differs slightly. The tone control board is designated PB777, though schematics reference PB727, differing mainly in power feed via a 1k resistor.
Context
The L-309 followed the L-308 and introduced Luxman’s Linear Equalizer, a defining feature carried forward into later models. It was succeeded by the L-309V in late 1975 as part of Luxman’s 50th-anniversary "V" series. Key changes in the V model included moving the phono 1 impedance selector to the front panel, adding a 3-position muting switch (0 dB, -10 dB, -20 dB), removing front tape I/O jacks, and upgrading speaker terminals. The L-309 and L-309V were designed to pair with the Luxman T-300U tuner.
Market
Recent listings show L-309V units priced from $253.50 to $1,426, with higher values reflecting restored or fully serviced condition. Common issues include sudden DC offset on one channel triggering the protection relay, blown output transistors causing extensive collateral damage, and bias sensing transistors detaching from heatsinks due to reliance on thermal compound alone. The equalizer filter switch can develop up to 20 ohms of contact resistance, and internal switch contacts are prone to dislodging. Fuse holders on the PB1024 power board were poorly fitted, and the germanium diode on this board often fails with age. Restoration typically involves a full recap, replacing the RC4558 op-amp with a quieter OPA2604, and substituting output transistors with modern equivalents like MJ15024 and MJ15025. Cleaning the filter switch requires contact spray, IPA soaking, and lubrication after drying.
eBay Listings
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