Linn Sondek Isobarik
The Linn Sondek Isobarik is one of the most physically imposing loudspeakers of the 1970s, and one of the least documented in surviving period literature. Most of what is known comes from a single retrospective review in Hifi Archive, which supplied the detailed technical description and the 1977 introduction date for the later DMS version. The original Isobarik is even thinner on the record. It was a 2-way design with smaller bass drivers using cloth roll surrounds, and its crossover was mounted on the back panel, a sign of its compact size compared to what followed.
The name comes from the defining trick: the bass drivers are mounted push-push, face to face in a sealed enclosure, so the sound from both combines internally before reaching the room. The later Sondek Isobarik DMS (introduced 1977) went to a 3-way system with larger 200mm bass units with rubber roll surrounds. The 3-way crossover sits at 375Hz and 3.5kHz with phase correction. The midrange driver has a large magnet and a rear cavity, and the dome tweeter is particularly efficient. The DMS was sold at £1150 per pair, ex-works.
The Hifi Archive review is candid about the Isobarik's character. It echoes period assessments of its thunderously clean bass (Audio, March 1983, p.82), described by J. Atkinson in Hifi News & Record Review as having "low distortion, tremendous dynamic range" (Audio, March 1983, p.82). It was described as a monitor speaker designed to reveal program faults, one that "takes no prisoners." The bass was extremely low, tight, and fast. It was not an efficient speaker, though, and it demanded high-quality, high-powered amplification, proper stands, and careful placement. It was also enormous: "two men are required to move one speaker." The same review concluded that in terms of absolute fidelity, the DMS had yet to be bettered.
Known specifications (DMS model):
- Type: 3-way, sealed enclosure with push-push bass loading
- Nominal impedance: 4 ohms
- Frequency response: 50Hz–20kHz ±3dB
- Sensitivity: 85dB SPL at 1 watt at 1 meter (anechoic)
- Crossover frequencies: 375Hz and 3.5kHz
- Connection: 4-pin DIN input
No exact dimensions, production end date, or current market values are documented. The record on this model is thin — but what survives describes a serious, uncompromising speaker that remains a benchmark in Linn's history.
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