LUXMAN A2500
¥ 42,100 (released in December 1972)
Commentary
Bulb-type power amplifier kit corresponding to the improved version of KMQ8.
6RA8, a 3-pole tube with low internal resistance and excellent low-frequency characteristics, and OY14 type transformer with excellent characteristics are used in the output stage. The 3-pole tube can be used as a 5-pole tube and requires a high drive voltage. The A2500 uses a cathode-coupled Mulard circuit in the drive circuit to obtain sufficient drive voltage and reduce the time constant for the low-frequency range.
To improve the bare characteristics of the amplifier, 6AQ8 is used for the first stage and 12AU7 for the phase inversion stage. Together with the output stage, 3-pole tubes are used for all stages. This configuration makes the amplifier excellent in bare characteristics.
The amount of NFB can be varied by securing excellent bare characteristics in A2500.
The standard amount of NFB is set at 14 dB, and it is possible to obtain satisfactory characteristics as an audio amplifier by applying only 6 dB of NFB, which is about half of this amount.
The hood was sold separately as an option.
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Model Rating
| Type | Bulb type power amplifier kit |
| Continuous effective output | 10W + 10W (4 ω, 8 ω, 16 ω) |
| Total harmonic distortion factor | 1% or less (NFB14dB) 2% or less (NFB6dB) |
| Frequency characteristic | 20 Hz to 20 kHz - within 1 dB (NFB14dB) 30 Hz to 20 kHz - Within 1 dB (NFB6dB) |
| Input sensitivity | 750mV(NFB14dB) 290mV(NFB6dB) |
| Input impedance | 100k Ω |
| Residual noise | 0.5 mv or less (NFB14dB) 1 mv or less (NFB6dB) |
| Attachment | Input level set Power connector for preamplifier (A3300) |
| Vacuum tube used | 6RA8x4 12AU7x2 6AQ8x1 |
| Semiconductor used | SD1Bx4 S1RB-40x1 1S1850x1 |
| Power consumption | 140W at maximum output |
| External dimensions | Width 410x Height 145x Depth 190 mm |
| Weight | 9.6kg |
| Sold Separately | Bonnet B-60 (¥ 5,000) Assembly Manual (¥ 500) |
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