LUXMAN SQ700X
¥ 45,000 (around the early 1970 s)
Commentary
Pre-main amplifier with orthodox circuit design and unique design.
The equalizer stage of the preamplifier section is a two stage direct connection type using PNP and NPN type transistors. Linearity is improved by increasing the power supply utilization factor, and stability is improved by applying DC feedback from the second stage collector to the first stage emitter.
This circuit uses specially selected low-noise transistors and capacitors such as tantalum and Meiler with low leakage current to achieve low distortion.
The electrolytic capacitor is eliminated from the coupling capacitor between stages.
The main amplifier circuit uses a double-power supply system and a single-stage differential amplifier circuit for all stages.
Pure complimentary service system composed of PNP type and NPN type power transistors is adopted for the output stage to eliminate crossover distortion.
Equipped with an attenuator, the gain can be reduced to approximately 1/8.
LUX type NF is used for tone control.
The left and right channel tone adjustment knobs are independent, and a click stopper is attached to indicate the approximate amount of increase or decrease. The range of control can be changed by changing the bending point frequency by two points for both low and high frequencies, allowing for fine control.
In addition, it has a defeat switch so that it can return to the flat characteristic with one touch.
There are two types of speaker jacks.
The front panel is made of aluminum material with hairline processing and finished with white gold anodized aluminum dyeing.
The same finish is applied to the knob.
The hood uses heat-resistant high-impact styrene with surface leather processing.
You can put it in a separately sold wood case.
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Model Rating
| Type | Pre-main amplifier | ||||||
| Main Amplifier Section | |||||||
| Continuous output | 20W + 20W (8 Ω, both channel operation) 25W/25W (8 Ω, single-channel operation) |
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| Total harmonic distortion factor | 0.1% or Less (8 Ω, 20W) | ||||||
| Cross modulation distortion factor | 0.1% or Less (8 Ω, 20W) | ||||||
| Power bandwidth | 10 Hz to 50 kHz -3dB (0.1%) | ||||||
| Input sensitivity | 430 mv (8 Ω, 20W) | ||||||
| Input impedance | 40k Ω | ||||||
| Residual noise | 0.5 mV or less | ||||||
| Damping factor | 38 (8 Ω) 76 (16 Ω) |
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| Preamplifier Section | |||||||
| Output voltage | Pre out:430mV | ||||||
| Output impedance | Pre out : Approx. 100 Ω | ||||||
| Frequency characteristic | 10 Hz to 50 kHz -1dB | ||||||
| Total harmonic distortion factor | 0.04% or Less (1 kHz, 1 V) | ||||||
| Input Sensitivity / Input Impedance | Phono1/2 : 2mV/50k Ω Aux1/2 : 120mV/50k Ω |
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| Signal-to-noise ratio | Phono1/2 : 60 dB or more Aux1/2 : 70 dB or more |
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| Maximum allowable input | Phono:200mV(1kHz) | ||||||
| Residual noise | 45 μ V or less | ||||||
| Tone control | LUX System NF Type with Bending Point Switching Low-range bending point : 250 Hz, 500 Hz High-frequency curve point : 2.5 kHz, 5 kHz |
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| Attachment | Attenuator SP Switch Tone defeat switch Headphone jack |
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| <General> | |||||||
| Semiconductor used |
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| Power consumption | 100W (8 Ω at maximum output) | ||||||
| External dimensions | Width 373x Height 125x Depth 227 mm | ||||||
| Weight | 7.8kg | ||||||