Audio Database

The

Technics SU-7700
45,800 yen(around the 1976 time)

Description
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The Integrated Amplifier which adopted the sub- termination structure in order to realize straight circuitry.

The termination is directly linked with the printed circuit board, without using a wire, and an input signal is straight inputted into a circuitry.
Moreover, the straight transmit is enabled according to a sub- termination layout.

IC stream composition is adopted as an equalizer circuitry. Circuitry makes the output stage the emitter-follower of the constant current load intensity by making into the first rank the differential amplification of the Current-mirror load intensity from which the operating current with very little noise can be chosen.
Since the large gain of the first rank is taken, the reduction of a noise level has been realized.
Moreover, in order to acquire the exact frequency characteristic, the polypropylene capacitor of deflection is used for an equalizer element }2% with the metal film resistor of deflection }1%.

The first rank of a main-amplifier part constitutes the differential amplifier using the pair transistor of one package, and is operated by the Current-mirror load intensity. High gain is obtained to a low distortion by the first rank, and it has become the offensive to which the negative feedback by NF technology was applied.
For the power transistor, the mass transistor was used by the complimentary, and a low distortion and low noise-ization are measured to it.

A protection network-cum-the muting circuit using a relay is carried, and the noise at the time of power-source on/off is stopped.

The newly developed high-density volume transformer that elaborated the technology on the coil and wound the coil around the small space with high density is adopted as a power-source part. For this reason, a volume bulk density is large and has obtained the efficient high output. Moreover, a regulation is also excellent and leakage flux has the special features, like it is few. A 10,000-micro F electrolytic capacitor is adopted as a capacitor.
The constant-voltage regulated power supply of }2 power source which used a transistor and zener diode for preamplifier parts is adopted. Furthermore, the common-emitter power source of the first rank differential amplifier of a main amplifier is constant-voltage-ized with zener diode, it supplies, and the stable amplification is enabled.

The Subsonic Filter using NF loop of the equalizer circuitry is carried.

Since it has the composition that the selector in sound-recording mode became independent of a tapes monitor, it is also possible to play other sources during dubbing.

The step type is adopted as a volume 41 point.

having adopted the newly developed volume as a tone control -- the middle point of a thumb -- a circuitry -- signal circuit blank measure. In this location, a signal circuit serves as only equalizer amplifier and power amplifier, and serves as very simple circuitry.
The tone control circuit uses NF circuitry of a main amplifier.

The high light filter is carried.

A germanium diode is adopted as a rectification and the output Direct-reading power meter which raised the linearity at the time of the Koide power is carried.

Internal
Newly The Low
The newly developed high-density
volume transformer adopted by SU-7700
The pair transistor of one package Low noise equalizer IC

Rating of a mode
Form Stereo Integrated Amplifier
<Power amplifier part>
Effective output (both channel)
1kHz: 70W+70W (4ohms)
53W+53W (8ohms)
20Hz - 20kHz : 50W+50W (8ohms)
THD 0.06%
Output bandwidth (both ch(es), 8ohms) 8Hz - -55kHz three dB
Remains noise 0.6mV
Dumping factor 60 (8ohms)
Load impedance Main or Remote: 4ohms - 16ohms
Main+Remote: 8ohms - 16ohms
<Preamplifier part>
Input sensitivity/impedance Phono: 2.5mV / 47kohm
Tuner, Aux, Tape1, 2:150mV / 47kohm
The Phono maximum input (1kHz, RMS) 150mV
SN ratio (IHF-A) Phono:78dB
Tuner, Aux: 97dB
Frequency characteristic Phono:RIAA standard curve}0.2dB
Aux: 5Hz-80kHz+0 -3dB
Tone control Bass: 50Hz, }12dB
Treble: 20kHz, }12dB
Light filter EQ Subsonic: 30Hz-12dB / oct
High: 8kHz-6dB / oct
Output voltage Tape1, 2:150mV
<Synthesis>
Power source AC100V, 50/60Hz
Power consumption 122W
Dimensions Width 410x height 140x depth of 315mm
Weight 7.2kg