Lo-D HA-630
¥ 69,800 (released in 1976)
Commentary
Pre-main amplifier that uses Dynaharmony (E-class drive).
The power amplifier uses the Dynaharmony (E-class drive) system to achieve high power efficiency.
The class A drive circuit adopts a current mirror circuit and performs push-pull drive of the power stage.
A four power supply system of ± 67 v high voltage and ± 31.5 v is adopted for the power supply. High-speed power switching is performed for the instantaneous level of the music program, and dynamic margin for the dynamic range of the music program is improved to achieve high efficiency.
We also use high-speed switching elements such as high-voltage high-speed switching diodes and high-current high-speed switching diodes that have been developed especially for the Dynaharmony system.
The pre-equalizer stage has a 3-stage direct connection structure using a PNP transistor for the first stage differential.
The tone control section combines a high-gain and high-stability ICHA 1456 with an NF-type circuit to achieve a low distortion rate.
It is also equipped with a tone defeat switch. When the tone switch for adjusting the sound quality is switched to defeat mode, flat frequency characteristics can be obtained instantly regardless of the position of the tone control.
A 32-contact attenuator is used for volume control, enabling precise level control.
Equipped with a 3-stage gain selector, the volume can be adjusted by attenuator to 0 db, -15dB or -30dB depending on the efficiency of the speaker.
Equipped with a subsonic filter, high filter and loudness control.
Built-in electronic protection circuit.
The wood case in the picture was sold as an optional item sold separately.
Model Rating
| Type | Pre-main amplifier |
| Power Amplifier Unit | |
| Circuit system | High-Efficiency Pure complimentary service OCL with 4-Power Supply Directly Connected to 2-Stage Differentials (Dynamic harmony system) |
| Effective power | 60W + 60W (8 Ω, 20 Hz to 20 kHz, both channel drive) 85W + 85W (8 Ω, 1 khz, both channel drive) 110W/110W (8 Ω, 1 kHz, single-channel drive) |
| Dynamic Power (IHF) | 320W (8 Ω) |
| Total harmonic distortion factor | 0.3% (Effective Output, 1 kHz, 8 Ω) |
| Intermodulation distortion factor (70 hz : 7 khz = 4 : 1) | 0.05% (at 1/2 Effective Output) |
| Output Bandwidth (IHF) | 10 Hz to 50 kHz |
| Output terminal | A, B : 4 Ω ~ 16 Ω A + B : 8 Ω ~ 16 Ω Headphone terminal : 4 Ω ~ 16 Ω |
| Damping factor | 30 or More (1 kHz, 8 Ω) |
| Preamplifier Section | |
| Circuit system | Equalizer amplifier : 1-stage and 3-stage differential connected Control Amplifier : NF Type |
| Input Sensitivity / Impedance | Phono1, 2 : 2.3mV/50k Ω Tuner, Aux, Tape PB1, 2 : 100mV/50k Ω |
| Phono maximum allowable input | Phono1, 2 : 230 mV (RMS, 1 kHz) |
| Output Level / Impedance | Tape rec (pin) : 100mV/1k Ω Tape rec (din) : 40mV/80k Ω |
| Frequency characteristic | Phono (RIAA deviation) : 30 Hz to 15 kHz ± 0.5 dB |
| Tone control | Bass : ± 10 dB (100 Hz) Treble : ± 10 dB (10 kHz) |
| Filter | Low : 25 Hz, 12dB/oct. High : 8 kHz, 6dB/oct. |
| Loudness control (Volume -30dB) | + 8 dB (100 Hz), + 4.5 dB (10 kHz) |
| S/N (IHF, A Network) | Phono:75dB Tuner, Aux, Tape PB : 90 dB |
| Gain selector | 0, -15, -30dB |
| <General> | |
| Semiconductor used | Transistor : 44 pcs Diode : 43 pcs IC : 1 |
| Power supply voltage | 100 VAC, 50Hz/60Hz |
| AC outlet | Power switch interlock : 1 system Power switch not linked : 2 systems |
| Rated power consumption (Electrical Appliance and Material Control Law) | 120W |
| External dimensions | Body : Width 435x Height 144x Depth 353 mm Wood Case : Width 467x Height 179x Depth 400 mm |
| Weight | 11kg |
| Sold Separately | Wood Case LA-200 (¥ 6,500) |