Sony APM 707AV

The speaker weighs 29 kilograms and has a 30 cm square woofer. It takes up a lot of room, and the geometry is odd enough that people look at it first.

Overview

The Sony APM 707AV is one of the boldest consumer loudspeaker experiments of the 1980s. It belongs to Sony’s APM (Accurate Pistonic Motion) series, which came out while the company was pushing hard into high-fidelity audio with engineering-first thinking. It is not another box with cones. The whole APM line was built to eliminate the breakup modes that plague traditional paper cones. Sony did it with rigid, flat, square drivers that have honeycomb-cored diaphragms and edge-wound voice coils. The 707AV carries the “AV” designation, which means it was tailored for audiovisual use. That suggests a slightly more durable build and some tolerance for dynamic, cinematic content, though it remained fundamentally a high-end stereo speaker.

The 707AV never followed the usual path of mainstream adoption. The look alone, with angular drivers in a boxy cabinet, divided opinion. For people who valued clarity over comfort, it became a cult object. Owners report a startlingly transparent sound, especially in the midrange, where vocals and acoustic instruments come through with lifelike articulation. The controlled dispersion of the square drivers contributes to a tightly focused stereo image, which makes it easy to pinpoint instruments in a mix. The cost is that some describe the tonal balance as clinical or bright, without the warmth many associate with analog-rich systems of the era.

Physically, the 707AV is a substantial speaker. It stands 730 mm tall and weighs 29 kg. One source labels it a bookshelf speaker, but the dimensions and mass say floorstanding, and the engineering fits that. Some configurations use a passive radiator, branded ABR (Accurate Bass Radiation), to extend low-frequency response without the port noise of a bass reflex system. Even so, collectors note that the bass is tight and well controlled but lacks the visceral punch of larger conventional woofers. That makes it better suited to critical listening than room-shaking playback.

Specifications

Key Features

30 cm Square Woofer with Honeycomb Diaphragm

The most visually striking part of the APM 707AV is its 30 cm square woofer, an anomaly among round cones. The driver is part of Sony’s APM series, which used a flat, rigid diaphragm with a honeycomb core to resist flexing and breakup at high excursions. The square shape was not just for show. It allowed a larger radiating surface within a constrained cabinet width, and it was engineered to move as a perfect piston across its operating range. The edge-wound voice coil further reduced mass and improved thermal efficiency, which contributed to cleaner bass and midbass reproduction.

ABR Passive Radiator for Extended Bass

One source describes the system as bass reflex. Another identifies an ABR (Accurate Bass Radiation) passive radiator, specifically a 324 cm² plane type, dedicated to enhancing low-frequency output. The two accounts suggest possible regional or production-run variations. The passive radiator design avoids port turbulence and allows deeper bass tuning in a more compact enclosure, though it adds complexity to the cabinet’s internal loading. Owners should verify the specific configuration when assessing or restoring a unit.

Anti-Magnetic Shielding for AV Use

The 707AV is marked as an anti-magnetic type. It was designed to sit near video equipment without interfering with CRT displays, a critical feature for its intended role in early home theater setups. The magnetic shielding extended to all drivers, so placement near televisions or projectors was safe. Combined with the “AV” designation, this shows Sony aiming to bridge high-fidelity audio with the emerging audiovisual market of the mid-1980s.

Automatic Recovery Protection Circuit

The 707AV has an automatic recovery type protection circuit, which guards against amplifier clipping and thermal overload. This was relatively advanced for consumer speakers at the time, and it helped prevent damage during high-volume playback or amplifier faults. The circuit disengages protection once conditions normalize, so there is no manual reset.

Controlled Dispersion from Square Drivers

The square geometry of the APM drivers is not merely cosmetic. It shapes the speaker’s radiation pattern. Round cones tend to beam at high frequencies, while the flat, square diaphragms offer more uniform dispersion control, particularly in the horizontal plane. This contributes to the speaker’s celebrated stereo imaging and a stable soundstage even off-axis. Collectors note that proper placement is critical, since the focused output rewards precise toe-in and room symmetry.

Collectibility & Value

The Sony APM 707AV has a niche following among vintage audio enthusiasts who appreciate its engineering audacity and midrange clarity. Its collectibility is tempered by a well-documented reliability issue: the foam surrounds on the square woofers and midranges are prone to deterioration with age. Unlike standard round drivers, these square units are difficult to re-foam, because replacement parts and specialized service providers are hard to find. Fully restored pairs in good cosmetic condition are rare and can command prices between $400 and $800, depending on market availability. Given the fragility of the drivers, untested or non-functional units hold minimal value unless intended for parts or restoration projects.

Similar items on eBay

No exact Sony APM 707AV listings are live right now — these searches show current Sony and similar vintage audio gear on eBay:

As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.

Related Models

• Sony 252-D
• Sony 262 SL
• Sony AC-148A
• Sony APM 10
• Sony APM 100AV