Audio Database


Lo-D HA-500F
89,800yen(1975 release)

The Integrated Amplifier which carries length type power FET.

Length type power FET which attracted attention as a new element is adopted as an amplification element.
Since this element does not have the carrier storage effect like a general transistor, it can be [ its velocity of switching ] quick, and it is stabilized to a high region and it can apply NFB. Moreover, the complimentary element of N channel and P channel can be obtained, and also the high input impedance and low-power-output impedance characteristic which are expected as an audio amplifier, and a smooth pinch-off property are shown. Moreover, it has a negative temperature coefficient and has various merits, such as being hard to start a thermal run away.

In HA-500F, this length type power FET is adopted as a power part, and it has become push pull pure complimentary OCL circuitry by length type power FET of N channel and P channel.
While a constant current circuit raises the gain of the first class stage, the property which was excellent in the stable operation with a development of a new drive circuitry has been acquired.

The differential amplifier which used the high resisting pressure low-noise transistor for the first rank is used for the equalizer stage. And the following stage raises the gain of the first rank by being referred to as FET, and the 3rd step is constituted from an emitter-follower by a bipolar transistor, and it is driving it with ±2 power source.

When a source impedance is high to the first rank of a tone control part, FET with little noise is adopted as it, and in it, the input circuit without a failure of the SN ratio by a volume location is constituted.

22 contact switchpoint type Attenuator with little right-and-left interlock error is adopted as a volume switchpoint.
Moreover, the level fine tune by a 3 steps of additive expression gain selector is also possible.

Loudspeaker B level adjustment convenient for the compare audition of a different loudspeaker is carried.

The loudness switchpoint and the tone-defeat switchpoint are carried.

The wood case was sold as an option option.


Rating of a mode
Form Integrated Amplifier
<Power amplifier part>
Circuit system 1 step of differential whole page hardwired-connection length
type power FET pure complimentary OCL
Effective output
20Hz - 20kHz, both ch(es) drive : 50W+50W (8ohms)
1kHz, both ch(es) drive : 55W+55W (4ohms)
55W+55W (8ohms)
1kHz, one-side-channel drive : 60W/60W (4ohms)
60W/60W (8ohms)
THD 0.3% (at the time of an effective output)
0.008% (at the time of 1 / 2 effective output 1kHz)
Cross modulation distortion (70Hz:7kHz=4:1) 0.3% (at the time of an effective output)
0.1% (at the time of 1W output)
Output bandwidth 5Hz - 37kHz
Frequency characteristic 10Hz-20kHz+0.5 -1 dB
Input sensitivity/impedance 1V/55kohm
Output-terminal A, B:4ohms - 16ohms
A+B: 8ohm-16ohm
Headphone jack: 4ohms - 16ohms
Dumping factor 50 (1kHz, 8ohms) or more
S/N (IHF, A network) 100dB or more
<Preamplifier part>
Circuit system Equalizer amplifier: The differential three-step hardwired connection per step, an FET using
Control amplifier: NF form, a first rank FET using
Input sensitivity/impedance Phono1:2mV/50kohm
Phono2:2-5mV/50kohm (Low-High switching)
Tuner, Aux, Tape PB1, 2:100mV/50kohm
Mic: 2mV/25kohm
Phono maximum permissible input Phono1:280mV (RMS, 1kHz)
2:280-700mV (RMS, 1kHz) of Phono(es)
An Output voltage/impedance
Tape rec1, 2 : 100mV/1kohm
Pre out: 1V/4.7kohm (rate)
6V/4.7kohm (maxima)
Frequency characteristic Phono(RIAA deflection): 30Hz-15kHz±0.3dB
Tone control Bass: ±10dB (100Hz)
Treble: ±10dB (10kHz)
Filter Low: 40Hz, 6dB / oct
Loudness control (Volume-30dB) + 13dB (100Hz), +7dB (10kHz)
S/N (IHF, A network, input short-circuit) Phono:75dB
Tuner, Aux, Tape PB: 90dB
Attenuator - 5, -10, -20dB (addition is possible)
The semiconductor used Transistor: 42 pieces
FET: Eight pieces
Diode: 37 pieces
Supply voltage AC100V, 50Hz/60Hz
AC outlet Power-switch interlock: One line
Power-switch un-interlocking.: One line
Power dissipation
(Electrical Appliance and Material Control Law)
Dimensions Main unit: Width 435x height 144x depth of 388mm
At the time of a wood case using: Width 467x height 179x depth of 400mm
Weight 12kg
Option Wood case LA-200 (6,500yen)