LUXMAN L-504
¥ 78,000 (released in October 1973)
Commentary
A pre-main amplifier announced as a successor to the SQ-505 model.
The main amplifier section is designed to eliminate as much as possible the crossover distortion that is difficult to remove with a class B push-pull amplifier, especially the notching distortion in the high frequency range.
The class B driver stage uses PNP and NPN type transistors with excellent high-frequency characteristics, and the power stage uses pure complimentary service power transistors developed for LUX with excellent breakdown resistance without loss of high-frequency characteristics.
The pre-driver stage employs a differential amplifier circuit driven by constant current and is driven by a constant current from no signal to maximum output to keep the class B operation stage stable and minimize notching distortion. The transistors in this stage have a high cutoff frequency (ft) and a low collector output capacitance (Cob). The distortion factor in the high frequency range is almost the same as 1 kHz over all outputs.
The transistors used in the main amplifier are all can-type to ensure moisture resistance, durability and high reliability.
The tone control circuit uses LUX system NF type with simple variable characteristics. Mechanically, it is equipped with high / low level adjustment with click stop, high / low bending point frequency switching by 2 points, and independent tone defeat switch.
The equalizer circuit is a 3-stage direct-coupled circuit consisting of NPN, PNP, and NPN ultra-low-noise transistors with excellent voltage utilization factor. Excellent linearity and high signal-to-noise ratio are obtained. Excellent strain values are obtained by using transistors with high current amplification factor (hfe) and good linearity.
DC feedback is sufficiently applied to this circuit to improve DC stability, and deviation from the RIAA curve is kept within ± 0.5 dB by reducing the tolerance of the parts used to minimize variation.
The capacitors used in the input and output circuits are carefully selected from among the Meiler type and tantalum type capacitors with low leakage current, thereby minimizing the unpleasant shock noise when switching the switches.
Two 6800 μ F electrolytic capacitors are used in the filter circuit of the power supply section. In combination with a well-regulated power transformer, a stable power supply is realized.
As a countermeasure against shock noise when the power is turned on or off, a muting circuit is provided to separate the speaker circuit when the power switch is turned on or off. This circuit also protects the speakers.
There are two speaker outputs, main and remote, which can be used separately or simultaneously.
Equipped with an attenuator switch, the volume can be reduced to -18dB with one button.
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Model Rating
| Type | Stereo integrated amplifier | ||||||||
| Main Amplifier Section | |||||||||
| Continuous effective output | 35W + 35W (8 Ω, simultaneous operation for both channels) 40W/40W (8 Ω, single-channel operation) |
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| Total harmonic distortion factor | 0.03% or Less (8 Ω, 35W) | ||||||||
| Cross modulation distortion factor | 0.04% or Less (8 Ω, 35W, 70 hz : 7 khz = 4 : 1) | ||||||||
| Output bandwidth | 5 Hz to 50 kHz -3dB (0.1%) | ||||||||
| Frequency characteristic | 10 Hz to 60 kHz -1dB | ||||||||
| Input sensitivity | 480 mv (8 Ω, 35W) | ||||||||
| Impedance | 50k Ω | ||||||||
| Residual noise | 0.5 mV or less | ||||||||
| Damping factor | 35 (at 8 Ω Load) | ||||||||
| Attachment | Attenuator (-18dB) Main speaker switch Remote speaker switch Headphone jack |
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| Preamplifier Section | |||||||||
| Standard output voltage | Pre out:480mV Rec out:120mV |
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| Maximum output voltage | Pre out:4.5V | ||||||||
| Output impedance | Pre out : Approx. 100 Ω Rec out : Approximately 100 Ω |
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| Frequency characteristic | Aux1 : 10 Hz to 50 kHz -1dB | ||||||||
| Total harmonic distortion factor | Aux1 : 0.04% or less (1 kHz, 1 V) | ||||||||
| Input sensitivity | Phono1, 2 : 2.7 mV Tuner, aux1, 2 : 120 mv |
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| Input impedance | Phono1, 2 : 65k Ω Tuner, aux1, 2 : 50k Ω |
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| Signal-to-noise ratio | Phono1, 2 : 65 dB or more Tuner, aux1, 2 : 76 dB or higher |
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| Maximum Allowable Input (1 kHz) | Phono : 300 mv (R / M / S) 850mV(P-P) |
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| Residual noise | Approximately 25 μ V or less | ||||||||
| Tone control | LUX System NF Type with Bending Point Switching Low-range bending point : 150 Hz, 300 Hz High-frequency curve point : 3 kHz, 6 kHz |
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| Attachment | Tape Monitor Switch (2 systems) Tape-dubbing mode switch Tape connector (DIN standard) |
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| <General> | |||||||||
| Semiconductor used |
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| Power consumption | 150W (8 Ω simultaneous load, maximum output) | ||||||||
| External dimensions | Width 450x Height 160x Depth 268 mm | ||||||||
| Weight | 10kg | ||||||||