Audio Database


Lo-D HA-7700
99,000yen(around the 1979 time)

The power MOS FET loading Integrated Amplifier which applied the know-how acquired by HMA-9500 to the pre-main.

Switching speed 0.05microsec, Power MOS FET has attained the frequency characteristic of 1MHz (-2dB) of an amplification factor, and has realized the high-performance of single or more figures as compared with the conventional bipolar transistor. This has realized power gain of 85dB in 100kHz of nakedness properties, the negative feedback stabilized [ 100kHz or ] enough started, and moreover, since switching speed is quick, the push-pull operation excellent also in B class circuitry has been realized.

In order to demonstrate the performance of the power stage to the maximum extent, the simple three-step power circuitry with few phase changes is adopted.
Furthermore, stability of operation is raised by having a whole page DC amplifier stream composition.

By three-step hardwired connection of the interrupt-control-logic circuitry, current mirror type differential circuit, and SEPP circuit of a cascode differential, the equalizer-amplifier part has secured 300mV of allowable inputs to SN ratio Input sensitivity of 2.5mV of 85dB.
Moreover, SN which was excellent also in head amplifier with a three-step hardwired-connection stream composition is secured.

The power-source part is stopping the Tran Gent crosstalk by carrying a right-and-left independent-source transformer and a mass capacitor.

In order to unite the input of amplifier with the recommendation load resistance of a cartridge, the Phono multiple contact switch is carried.
One step of values of the resistor connected to the input of Phono1 and 2 can be switched by four steps and MC position in man-month position.

The Subsonic Filter is carried.

Rating of a mode
Form Integrated Amplifier
<Main-amplifier part>
Effective output 70W+70W (8 ohms, both channel drive, 5Hz - 30kHz)
THD 0.008% (at 5Hz - 30kHz, the time of an Output power 8ohms)
0.02% (at 5Hz - 100kHz, the time of 35W output 8ohms)
Cross modulation distortion (60Hz:7kHz=4:1) 0.008% (at the time of an Output power 8ohms)
0.003% (at the time of 35W output 8ohms)
Frequency characteristic DC-100kHz+0 -1 dB (DC)
Input sensitivity/impedance Main in: 1V/47kohm
SN ratio (IHF, A network) 115dB
Dumping factor 60 (1kHz, 8ohms)
Load impedance 4ohm-16ohm
<Preamplifier part>
Input sensitivity/impedance Phono1, 2 man month: 2.5mV/100 ohm, 22kohm, 47kohm, 100kohm
Phono1, 2 MC: 250 microvolts/100 ohms
Tuner, Aux, Tape play1, 2:150mV/47kohm
An Output voltage/impedance Tape rec out1, 2:150mV/600 ohms
Pre out: 1V/600 ohm
Phono maximum permissible input (1kHz, 0.01%) MM:300mV
THD (1kHz) Phono1, 2 man month: 0.002% or less (AT Rec out, 1V)
Phono1, 2 MC: 0.01% or less (AT Rec out, 1V)
Tuner, Aux, Tape play1, 2:0.005% or less (AT Pre out, 1V)
Frequency characteristic Phono1, 2:20Hz-20kHz±0.2dB (RIAA deflection)
Tuner, Aux, Tape play1, and 2:10Hz-100kHz+0 -2.5 dB
SN ratio (IHF, A network) Phono1, 2 man month: 86dB
Phono1, 2 MC: 68dB
Tuner, Aux, Tape play1, 2:100dB
Tone control Bass: ±8dB (100Hz)
Treble: ±8dB (10kHz)
A low filter 15Hz, 6dB / oct
Muting -16dB
Supply voltage AC100V, 50Hz/60Hz
Power consumption
(Electrical Appliance and Material Control Law)
AC outlet Power-switch interlock: Two lines
Power-switch un-interlocking.: One line
Dimensions Width 435x height 164.5x depth of 383mm
Weight 16kg