SANSUI BA-90
¥ 36,300 (released in August 1968)
Commentary
A compact all-silicon transistor power amplifier developed in pursuit of sound transparency.
In addition to data, repeated listening tests are conducted to reduce the expansion of low-frequency sound and distortion at low output.
The output circuit uses a 3-stage direct-coupled circuit consisting of a pre-driver with a PNP transistor and a low-noise transistor to improve the distortion factor and IM distortion factor at low frequencies and small outputs.
In addition, a buffer amplifier keeps the input impedance constant regardless of the input adjuster.
It is equipped with a damping factor selection switch, enabling more faithful playback by adjusting to the optimum value of the speaker drive.
A protective circuit is provided to prevent damage to the power transistor when the output terminal is shorted accidentally.
SANSUI's proprietary pure electronic PSC circuit is used for this protection circuit, and a short-cut fuse is combined to further improve safety.
It has a headphone jack.
The power transistor is mounted on an aluminum extrusion heat sink to achieve heat radiation effect.
Equipped with an independent left / right speaker phase selector switch, the phase of the speakers can be switched with the switch.
Equipped with an oral / null balance switch, and when you test the switch, the left and right speakers are connected in series and sound disappears when properly balanced, so you can easily adjust the left and right balance.
Equipped with left and right independent volumes, each can be independently adjusted.
It has an input level adjuster that can be used with any preamp.
Model Rating
| Type | Stereo power amplifier |
| Effective power | 32W/32W ± 1 db (4 Ω) 28W/28W ± 1 db (8 Ω) |
| Music Power (IHF) | 90W ± 1 dB (4 Ω) 70W ± 1 db (8 Ω) |
| Harmonic distortion factor | 0.3% or Less (at Normal Output) 0.1% (at 1/2 output) 0.1% (at 1/10 output) |
| Intermodulation distortion factor (60 hz : 7 khz = 4 : 1) | 0.3% or less |
| Power Band Wiz (IHF) | 15 Hz ~ 40 kHz (8 Ω) |
| Frequency Characteristics (Normal Output) | 15 Hz to 100 kHz ± 1 dB |
| Input sensitivity (at rated output) | 1 v ± 3 db |
| Input impedance | 100k Ω or more |
| Load impedance | 4 Ω ~ 16 Ω |
| Damping factor | Low : 10 (8 Ω) High : 50 (8 Ω) |
| Hum and noise (IHF) | 80 dB or more |
| Channel separation | 50 dB or more |
| Power supply voltage | AC100V/117V/220V/240V, 50Hz/60Hz |
| Power consumption | 160VA |
| External dimensions | Width 187x Height 111x Depth 363 mm |
| Weight | 7.5kg |