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. Luxman, the Japanese manufacturer, released it in July 1969. It is a standalone amp derived from the main circuitry of the SQ38F integrated amplifier, and it uses the same NEC 50CA10 triode in the output stage. It was also sold as a kit, the KMQ60, for ¥45,000, so buyers could assemble and adjust it themselves. A bonnet for the unit was available separately for ¥4,500. The chassis is aluminum with a hairline silver finish and all-dark gray semi-gloss paint. The look is plain and minimalist, typical of Luxman's high-end 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). The first voltage amplification stage uses a 6267 tube in triode connection and a low internal resistance ball to improve high-frequency performance. The phase inversion stage uses high-transconductance 6DT8 tubes for gain. The output stage uses NEC 50CA10 triodes, as in the SQ38F. Buffer resistors sit at the first stage grid to keep frequency response stable when the volume control changes. 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. It relies on a tube-based design and careful impedance management. It was positioned as a premium option for people building a system from separate components, and the KMQ60 kit was available for those who wanted to build it themselves. It uses the NEC 50CA10 and the OY15 transformer.
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