Boston Acoustics A 70
The Boston Acoustics A 70 is a two-way bookshelf loudspeaker that the company's own catalog called "an old favorite" in its hi-fi lineup. It pairs an 8-inch acoustic suspension woofer with a 1-inch dome tweeter. Contemporary owner commentary praised it for delivering "tight, accurate bass from a relatively compact bookshelf speaker." The model was sold in pairs at around $300.
Documentation on the A 70 is thin. No production years, cabinet details, or crossover specifics beyond a 3 kHz point have surfaced in the archive's research. The most complete spec listing comes from Hifi-wiki, which records an 8-ohm impedance, 89 dB sensitivity, a 65 Hz to 25 kHz frequency response, and a recommended 10-100 W amplifier range. Dimensions are given as 37.5 cm high by 24.5 cm wide by 25 cm deep, with a weight of 6.5 kg. A second source, Vintage Audio Warehouse, lists slightly different figures - 14-3/4" H x 9-3/4" W x 10" D and 20 lbs. - and attributes those to a version using a "Custom ARC resonant container." What that ARC (Acoustic Resonance Chamber) actually does mechanically is not documented beyond the name.
The specs conflict on the woofer. Hifi-wiki lists a "10 cm woofer," which would be roughly 4 inches, while the Audio Review Forum states an 8-inch woofer. Given the cabinet size and the acoustic suspension design, the forum figure is almost certainly the correct one and the Hifi-wiki value a typo. Both are recorded here as published, since neither can be independently confirmed.
Known specifications:
- Type: Two-way bookshelf loudspeaker, acoustic suspension
- Woofer: 8-inch (per forum; Hifi-wiki lists “10 cm”)
- Tweeter: 1-inch dome
- Crossover: 3 kHz
- Impedance: 8 ohms
- Sensitivity: 89 dB
- Frequency response: 65 Hz – 25 kHz
- Recommended amplifier power: 10–100 W
- Dimensions: 37.5 x 24.5 x 25 cm (Hifi-wiki); 14-3/4" x 9-3/4" x 10" for ARC version (Vintage Audio Warehouse)
- Weight: 6.5 kg (Hifi-wiki); 20 lbs. for ARC version (Vintage Audio Warehouse)
- Original price: $300/pair
Audio (September 1987, p.46) noted the A70 had been "newly redesigned" as the A70 Series II. That confirms the model saw at least one revision during its run, though no details on what changed between versions have surfaced.
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