Sony APM 750AV (c. 1986)
A mid-range, AV-compatible bookshelf speaker from Sony's APM series. It has flat diaphragm drivers and a passive radiator for extended bass.
Overview
The Sony APM 750AV is a passive bookshelf speaker system released around 1986 as part of Sony's APM (Audio Perfection Module) series. Sony positioned it as a mid-range model for high-fidelity audio and AV use. The drivers have flat, square diaphragms instead of conventional cones, a design intended to reduce distortion and improve transient response. The enclosure is magnetically shielded. An ABR (Accurate Bass Radiation) passive radiator adds low-frequency output. An automatic recovery type protection circuit guards against overload.
Specifications
| Type | Bookshelf Type |
| Enclosure | Passive Radiator |
| Way system | 2 |
| Unit For low band | 170 cm² Plane type |
| Unit For high frequency | 9 cm² Plane type |
| Playback frequency band | 40 Hz to 20000 Hz (some sources cite 20 Hz to 20000 Hz) |
| Output sound pressure level | 89dB/W/m |
| Rated input level | 50W |
| Maximum instantaneous input level | 100W |
| Impedance | 6ohms |
| External dimensions | Width 280x Height 525x Depth 220 mm |
| Weight | 8.5kg |
Design
The APM 750AV uses flat, rigid diaphragm drivers for both low and high frequencies. Sony chose them over traditional cones to reduce distortion and improve transient response. The ABR (Accurate Bass Radiation) passive radiator extends the bass response. The drivers are magnetically shielded, so they won't interfere with nearby CRT displays. The automatic recovery type protection circuit safeguards the drivers during high-volume operation.
Reception & Use
The APM series is known for a bright, detailed sound. Owners praise the clarity and the unusual appearance of the speakers. The sound is revealing, so it can highlight imperfections in source material. Some users have reported degraded foam surrounds that needed replacement, a common maintenance issue on aging units.
Market
Used pairs of APM 750AV speakers have been listed for prices ranging from $50 to over $400, depending on condition. Foam surround degradation is a known issue, but a service manual is available to support repair.
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