LUXMAN MQ80
¥ 169,000 (released in October 1974)
Commentary
A stereo power amplifier using 6336A vacuum tube.
Dual triode 6336A used for OTL amplifier MQ36 is used for the output tube.
In the MQ80, one push-pull circuit per one channel is constructed using this 6336A, and 40W output is obtained at 8 Ω load.
An output transformer similar in appearance to the conventional OY15 type is used. However, in order to achieve the effect of cross-shunt push-pull operation, the primary side winding is divided into the plate side and the cathode side, and this is wound around the bifilar.
In addition, the high-frequency characteristics of the output transformer are extended to 200 kHz, and the phase characteristics are also excellent. Therefore, the naked characteristics of the amplifier are improved and the stability when negative feedback is applied is also excellent.
For the output stage of cross-shunt push-pull operation, 50% of the output voltage returns as negative feedback. In addition, 6336A requires a large drive voltage because of low rp and high Gm.
For this reason, we have adopted a powerful twin triode 12BH7A with large plate loss for the drive stage and constructed a cathode follower direct-coupled circuit for a powerful drive circuit. We have also adopted a twin triode 6AQ8 for the phase inversion stage and constructed a cathode coupled circuit. For the first stage, we have adopted a pentad 6267 for gain.
Model Rating
| Type | Bulb type stereo power amplifier | ||||||
| Continuous execution output | 40W + 40W (8 Ω, both channel operation) 45W/45W (8 Ω, single-channel operation) |
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| Total harmonic distortion factor | 0.5% or Less (8 Ω, 40W) | ||||||
| Frequency characteristic | 10 Hz to 60,000 Hz -1dB | ||||||
| Input sensitivity | 800 mv (8 Ω, 40W) | ||||||
| Input impedance | 80k Ω | ||||||
| Damping factor | 15 (8 Ω Load) | ||||||
| Residual noise | 0.5 mV or less | ||||||
| Semiconductors used |
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| Power supply voltage | 100V | ||||||
| Power consumption | 250W 350W at maximum output |
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| External dimensions | Width 435x Height 170x Depth 260 mm | ||||||
| Weight | 17kg |