Luxman MQ60 (1969)

A tube power amplifier introduced in 1969, based on the core design of the SQ38F, with high-frequency optimization and a distinctive chassis finish.

Overview

The Luxman MQ60 is a tube-type stereo power amplifier released in July 1969 by Japanese manufacturer Luxman. It was designed as a standalone amplifier derived from the main circuitry of the SQ38F integrated amplifier, sharing its use of the NEC 50CA10 triode in the output stage. The MQ60 was also offered as a kit, the KMQ60, for ¥45,000, allowing users to assemble and adjust it themselves. A bonnet for the unit was available separately for ¥4,500. The amplifier features an aluminum chassis with a hairline silver finish and all-dark gray semi-gloss paint, giving it a refined, minimalist appearance typical of Luxman’s high-end audio gear of the era.

Specifications

Product type	tube type stereo power amplifier
Production year	released in July 1969
Continuous output	30W/30W (4, 8, 16 Ω)
Total harmonic distortion factor	0.1% (at 1W output), 0.3% (at maximum output)
Frequency characteristic	15 Hz to 60,000 Hz -1dB
Signal-to-noise ratio	90 dB or more
Residual noise	0.7 mV or less
Damping factor	Approximately 15 (1 kHz)
Load impedance	4 Ω, 8 Ω, 16 Ω (switch switching)
Vacuum tubes used	50CA10 (4), 6DT8/6AQ8 (2), 6267 (2)
Semiconductors used	DS16A (4), DS16C (1)
Output transformer	OY15 type
External dimensions	Width 410 x Height 160 x Depth 205 mm
Weight	13.8 kg
Original price	¥62,000 (1969), ¥79,000 (around 1974)

Design

The MQ60 uses a circuit configuration based on the Mulard type (likely a reference to Mullard), with the first voltage amplification stage employing a 6267 tube in triode connection and a low internal resistance ball to enhance high-frequency performance. The phase inversion stage uses high-transconductance 6DT8 tubes to achieve gain, while the output stage relies on NEC 50CA10 triodes, as used in the SQ38F. Buffer resistors are placed at the first stage grid to stabilize frequency response against volume control variations. A phase correction circuit on the secondary side of the OY15 output transformer prevents instability under high-frequency, near-no-load conditions. The amplifier was also available in kit form as the KMQ60.

Context

The Luxman MQ60 was developed as a dedicated power amplifier version of the SQ38F’s core circuitry, emphasizing high-fidelity performance through tube-based design and careful impedance management. Its release positioned it as a premium option for audiophiles seeking modular system building, especially with the availability of the KMQ60 kit variant. The use of high-quality components like the NEC 50CA10 and OY15 transformer reflects Luxman’s focus on sonic precision during this period.