Lo-D HCA-7500
¥ 60,000 (around 1977)
Commentary
7500 series control amplifier.
The EQ circuit consists of three stages and five elements, with a low-noise bipolar transistor at the first stage, a constant current load at the second stage, and a pure complimentary service push-pull circuit at the last stage. The EQ circuit is driven by a ± 32 v power supply.
HCA 7500 has an excellent S / N ratio by selecting the elements and adopting a circuit configuration that considers the mechanism of noise generation.
Newly developed capacitors are used for both input and output.
Equipped with a cartridge load selection switch, the optimum load can be selected for various cartridges by switching between 4-stage load resistance and 4-stage load capacity.
The tone control circuit is a 6-stage FET differential constant-current bipolar push-pull 3-stage direct-coupled circuit. It uses carefully selected low-noise FETs and high-voltage low-noise transistors to achieve low distortion. Under the rated output of 1 V or less, it achieves low distortion over the 20Hz-20kHz band, where the distortion component is hardly detectable against residual noise.
With the HCA 7500, the tone volume is lost in the center, and the tone quality is continuously variable without waviness. In addition, a wide range of tone quality correction is possible by changing the turnover frequency and tone loss switch.
It is equipped with Sharp's characteristic low filter and high filter.
It uses a 32-contact detent volume.
Model Rating
| Type | Control amplifier | ||
| Circuit system |
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| Input Sensitivity / Impedance | Phono1, 2 : 2mV/100 Ω, 10k Ω, 50k Ω, 100k Ω / 100 pF, 200 pF, 300 pF, 400 pF Tuner, Aux, Tape play1, 2 : 100mV/50k Ω |
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| Maximum allowable input | Phono1, 2 : 350 mV (RMS, 1 kHz, distortion rate 0.01%) | ||
| Output Level / Impedance | Tape rec out : 100mV/600 Ω Output : 1V/600 Ω |
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| Frequency characteristic | Phono1, 2 : 20 Hz to 20 kHz ± 0.2 dB Tuner, Aux, Tape play1, 2 : 5 Hz to 100 kHz + 0 -1dB |
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| S/N ratio (IHF-A network) | Phono1, 2 : 87 dB Tuner, Aux, Tape play1, 2 : 100 dB |
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| Harmonic distortion factor (20 Hz to 20 kHz) | Phono1 and 2 : 0.005% Tuner, Aux : 0.005% |
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| Tone control | Bass : ± 10 dB (50 Hz) Treble : ± 10 dB (10 kHz) |
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| Filter | Low : 15 Hz, 12dB/oct. High : 8 kHz, 6dB/oct. |
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| Semiconductor used | FET : 4 pcs Transistor : 25 Diode : 12 pcs |
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| AC outlet | Power switch interlock : 2 systems Power switch not linked : 2 systems |
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| Pwer | 100 VAC, 50Hz/60Hz | ||
| Rated power consumption | 10W (Electrical Appliance and Material Control Law) | ||
| External dimensions | Width 480x Height 166x Depth 348 mm | ||
| Weight | 8kg |