DENON HA-1000
¥ 65,000 (around 1977)
Commentary
Head amplifier designed for MC cartridge.
The HA-1000 uses a separate power supply system with independent power supply units.
In addition, the main body has a magnetic shield made of silicon steel sheet so that the head amplifier can perform under all conditions.
Eight PNP type low-noise transistors, which are advantageous for voltage noise, are used in parallel for the first input stage, which has the most influence on SN ratio, in order to reduce noise.
The transistor used in the first stage is a PNP transistor with low current noise and voltage noise level of -147.5 db (V) per unit, which can be said to be the limit at present.
The second stage and subsequent stages are designed to provide stable deep NFB with little influence of transistor characteristic variations. The second stage is a special current mirror type differential circuit to obtain high gain.
The final stage consists of a Darlington complimentary service emitter-follower circuit with class A amplification, a wide dynamic range and low output impedance.
The voltage gain of the HA-1000 can be switched between two stages of MC cartridge (32 db, 24 db) and three stages of MM cartridge (0 db, PASS).
In the PASS mode, the input terminal is directly connected to the output terminal and the amplifier circuit jumps completely.
Some commercially available MC cartridges have an output impedance of approximately 100 Ω. In this case, there is a slight effect of inductance. Therefore, the input impedance of the HA-1000 is set to 100 Ω to suppress the high frequency characteristics due to the capacitance of the tone arm code and head amplifier input.
It has a built-in muting circuit to prevent unnecessary noise when switching.
Equipped with a high-cut filter.
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Model Rating
| Type | MC head amplifier |
| Input impedance | 100 Ω |
| Voltage gain | 32dB/24dB/MM(Pass) |
| Maximum output level | 3Vrms |
| Input equivalent noise level | -157dB (V) (RIAA / EQ + IHF-A, input short circuit) |
| Frequency characteristic | 8 Hz ~ 600 kHz + 0 -1dB |
| Harmonic distortion factor | 0.008% or Less (at 0.3 V Output) |
| Cross modulation distortion factor | 0.008% or Less (at 0.3 V output, 60 Hz : 7 kHz = 4 : 1) |
| Crosstalk (1 kHz) | -70dB or less |
| High-cut filter | 100 kHz, -6dB/oct. |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 10W |
| External dimensions | Amplifier Part : Width 125x Height 68x Depth 292 mm Power Supply : W 107x H 65x D 141 mm |
| Weight | Body : 1.8 kg Power Supply : 1.4 kg |
| Attachment | Low capacity output cord with gold-plated plug |
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