LUXMAN L-550X
¥ 269,000 (released in December 1983)
Commentary
The L-500X series pre-main amplifier is based on the L-500 series equipped with a single-stage amplifier, and has been improved overall with the aim of refining the ground circuit and enriching the input system.
The L-550X employs a class A operation method in which the bias current is fixed. In addition, it employs a single-stage amplifier with dramatically improved bare characteristics of the amplifier.
This single-stage amplification is a circuit that extracts a gain equivalent to that of multi-stage amplification at one stage by using an amplification element with excellent bare characteristics. In addition, the second stage is eliminated after eliminating the effect of the first stage by making the output stage independent. This eliminates problems such as the adverse effect of power supply noise and the deterioration of the slew rate due to the high-pass correction of the stagger.
In addition, the amplifier circuit is stabilized by using symmetric differential push-pull for the equalizer and power section and by installing the input to ground.
In order to solve the problem of interference between music signals caused by the slight fluctuation of the ground potential, the ground circuit is refined.
First, we removed the power source reference amplifier, which was a factor of fluctuation, from the inside of the amplifier, and constructed all clean earth reference type amplifier circuits. Then, we reviewed the input / output current loops of each amplifier circuit and separated and coupled each amplifier circuit to make each amplifier circuit independent. We also devised the ground circuit pattern to fix the reference potential.
Head amplifier is mounted to support MC cartridge.
The input part of the head amplifier uses a low-noise transistor superior to FET in S/N, and the output part is equipped with a high-speed transistor superior in linearity.
A pure focus capacitor is used for the block capacitor in the power supply.
Equipped with a linear equalizer, you can adjust the recording frequency of analog discs that tend to rise or fall toward higher frequencies. You can also adjust the sound field characteristics of the listening room.
The tone control allows you to select nine turnovers for both high and low frequencies.
Copper plating is applied to important parts of the chassis to eliminate electro-magnetostriction.
Model Rating
| Type | Integrated amplifier | ||
| Continuous effective output | 50W + 50W (8 Ω, both channels driven simultaneously, 20 Hz to 20 kHz) | ||
| Total harmonic distortion factor | 0.008% or Less (8 Ω, -3dB, 20 hz to 20 khz) | ||
| Cross modulation distortion factor | 0.008% or Less (8 Ω, -3dB, 60 hz : 7 khz = 4 : 1) | ||
| Input sensitivity | Phono MM:2mV Phono MC : 90 μ V (direct to equalizer) Tuner, DAD, Line : 150 mv main in:150mV |
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| Input impedance | Phono MM : 100 Ω, 50k Ω, 100k Ω Phono MC : 40 Ω, 100 Ω, 300 Ω Tuner, DAD, Line : 40k Ω Main in : 47k Ω |
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| Signal-to-noise ratio (IHF-A corrected) | Phono MM : 86 dB or more (5 mV input) Phono MC : 80 dB or more (250 μ V input) Tuner, DAD, Line : 105 dB or higher (input short) Main in : 105 dB or more |
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| Frequency characteristic | Phono MM : 20 Hz to 20 kHz ± 0.2 dB or less Phono MC : 20 Hz to 20 kHz ± 0.2 dB or less Tuner, DAD, Line : 10 hz to 100 khz -1dB or less Main in : 10 Hz to 100 kHz - within 1 dB |
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| Tone control | Maximum variation : + / - 9 dB Low-frequency curve point : 55 Hz, 77 Hz, 110 Hz, 155 Hz, 220 Hz, 310 Hz, 440 Hz, 620 Hz, 880 Hz High-frequency bending point : 620 Hz, 880 Hz, 1.2 kHz, 1.7 kHz, 2.5 kHz, 3.5 kHz, 5 kHz, 7 kHz, 10 kHz |
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| Pre-part output | pre out:150mV | ||
| Attachment |
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| AC outlet | Switched : Route 3, max300W Unswitched-1 line, max200W |
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| Power supply voltage | 100 VAC, 50Hz/60Hz | ||
| Power consumption | 310W (Electrical Appliance and Material Control Law) | ||
| External dimensions | Width 453x Height 174x Depth 470 mm | ||
| Weight | 20.0kg |