Audio Database

SU-7300
Commentary

A pre-main amplifier with a side terminal structure to realize a straight circuit structure.

A side terminal structure is adopted. All input signal terminals are laid out on the right side, and the speaker terminals are laid out on the left side. This realizes a circuit configuration according to the signal flow.

The equalizer circuit uses an IC of the first stage differential amplifier configuration with current mirror load.

In the pre-drive stage of the main amplifier section, a differential amplifier of the current mirror load is configured in the first stage to realize a low distortion factor. In addition, since tone control is performed using the NF circuit of the main amplifier, the circuit block has a simple structure consisting of an equalizer section and a power amplifier section.

The power supply circuit is equipped with a high-density winding transformer and 6,800 μ Fx2 electrolytic capacitor.

Equipped with a power meter that can switch the range between 0 dB and -10dB.
Germanium diode is used for rectification to improve linearity at small output power.

With independent tape monitor and recording mode selectors, you can switch the tape monitor switch to a different source while dubbing.

Equipped with a low filter and loudness switch.

Model Rating
Type Stereo pre-main amplifier
Power Amplifier Unit
Effective output (both channels)
1kHz: 42W + 42W (4 Ω)
39W + 39W (8 Ω)
20 Hz to 20 kHz : 36W + 36W (8 Ω)
Total harmonic distortion factor 0.08%
Output Bandwidth (both channels, 8 Ω) 8 Hz to 55 kHz, -3dB
Residual noise 0.7mV
Damping factor 45 (8 Ω)
Load impedance Main or Remote : 4 Ω ~ 16 Ω
Preamplifier Section
Input Sensitivity / Impedance Phono : 2.5mV/47k Ω
Tuner, Aux, Tape1, 2 : 150mV/47k Ω
Phono Maximum Input (1 kHz, RMS) 150mV
Signal-to-noise ratio (IHF-A) Phono:78dB
Tuner:97dB
Frequency characteristic Phono : RIAA standard curve ± 0.3 dB
Tuner : 7 hz to 80 khz + 0 to 3 db
Tone control Bass : 50 Hz, ± 12 dB
Treble : 20 kHz, ± 12 dB
Filter Low : 30 Hz, -6dB/oct.
Loudness control (Volume -30dB) 100Hz:+6dB
Output voltage Tape1 and 2 : 150 mV
<General>
Pwer 100 VAC, 50/60Hz
Power consumption 95W
External dimensions Width 410x Height 140x Depth 315 mm
Weight 6.0kg