Audio Database


Lo-D HMA-9500
230,000yen(one-set, around the 1979 time)

Stereo power amplifier which adopted Power MOS FET.

The first rank constitutes circuitry from differential amplifier and differential amplifier with which the 2nd step uses a current mirror circuitry as a load intensity.
Properties, like the mutual conductance of Power MOS FET is large, a linearity and the frequency characteristic are good, electrical-power gain also has them, and the complimentary property of N channel and P channel has gathered well, [ large ]It is simple circuitry of three steps including the power amplification stage.

The capacitor was lost from the inside of a NFB loop, and DC amplifier stream composition which removed even the input capacitor is adopted.
Moreover, the component partses which cause a tone-quality failure are eliminated, and the more exact waveform transmission is made possible.

The power transformer was formed in the right-and-left independency at the power-source part, and the crosstalk is eliminated by considering the stabilizing supply the rectification smoothing circuit of the power amplification stage, and for small signals as a right-and-left independent stream composition.
Furthermore, in order to reduce the interference between right-and-left channels, the design is carried out by the input/output of the symmetrical separate placement.

The input pin jack of a gilding treatment is adopted.

Rating of a mode
Form Stereo power amplifier
Circuit system Two-step differential-amplification preceding paragraph hardwired-connection power
MOS FET pure complimentary OCL circuitry
Effective output (both channel drive) 100W+100W (8 ohms, 5Hz - 100kHz)
120W+120W (8 ohms, 5Hz - 20kHz)
THD (8ohms) 0.01% (at the time of 5Hz - 100kHz, and an Output power)
0.005% (at the time of 5Hz - 20kHz, and an Output power)
0.002% (at the time of 1kHz and an Output power)
0.002% (at the time of 1kHz and 50W output)
Cross modulation distortion (60Hz:7kHz=4:1) 0.003% (at the time of 8 ohms and an Output power)
0.003% (at the time of 8 ohms and 50W output)
Frequency characteristic
DC: DC-100kHz+0 -0.5dB
DC-300kHz+0 -1dB
Low cut: 3Hz-300kHz+0 -1 dB
Input sensitivity/impedance 1V/50kohm
Channel separation
(Input short-circuit)
85dB (5Hz - 100kHz)
95dB (5Hz - 20kHz)
S/N (input short-circuit) 110dB
Dumping factor 70 (5Hz - 20kHz)
The optimal load impedance 4ohm-16ohm
Supply voltage AC100V, 50Hz/60Hz
Power dissipation 350W (Electrical Appliance and Material Control Law)
Dimensions Width 435x height 192x depth of 410mm
Weight 28kg