KEF Model 105 (1977–)
A British floorstander that became the reference other speakers were measured against. Labs bought their own.
Overview
Most speakers of the era were sold to audiophiles. The Model 105 was also bought by the people who build and test loudspeakers. High Fidelity (June 1980, p.65) noted that since its 1977 introduction the Model 105 had been adopted by audio testing laboratories and speaker manufacturers as a reference for evaluating other loudspeakers.
KEF built the 105 on computer-aided digital analysis. It used modeling to optimize the drivers, the crossover network, and the enclosure toward a defined Target Acoustic Response, rather than endless trial-and-error prototyping. The company was explicit that this technology "did not previously exist" and that the 105 was where it proved itself. According to KEF's own contemporaneous documentation, the same computer-aided techniques developed for the production of the critically acclaimed Model 105 were later carried down to smaller models in the line.
The production side mattered as much as the design. Precision-matched pairs are what you need if a speaker is going to serve as a measurement reference.
The 105 didn't stand still. By 1980 KEF had introduced the Model 105 Series II, which the period press described as embodying "several significant technical features and improvements never before available" - including a protection scheme. Audio (August 1980, p.13) and High Fidelity (June 1980, p.65) both carried the announcement, and both framed it the same way: the original 105 had earned its reference reputation, and the Series II built on it. Later literature references the Model 105.2 and Model 105.4. KEF singled out their head assemblies as an example of its research and engineering, with each unit housed in its own enclosure of selected dimensions shaped to support optimum radiation across the operating range.
By the end of the decade the Reference Series had moved on again. KEF's 1990 documentation describes the four-way 105/3, which drew on the company's research into how speakers interact with room acoustics. It used coupled-cavity bass loading for deep bass from small enclosures, conjugate load matching to use amplifier power fully, and KUBE, KEF's proprietary bass equalizer, which the company claimed produced the bass of cabinets eight times as large. The 105/3 was also the first Reference Series model to use Uni-Q technology, with the tweeter placed inside the woofer's voice coil. It is a long way from the 1977 original, but it carries the same nameplate.
What does all this mean for someone actually hunting one today? The 105's reputation as a lab reference is the strongest argument in its favor — it was built to be trusted, matched, and consistent. The Series II protection circuitry is a genuine plus for a speaker of this age, since drive units from this period aren't getting any easier to source. Collectors should expect the usual caveats for a multi-decade British floorstander: condition of the drive units and crossover components is everything, and the precise series matters, since Series I, Series II, and the later .2/.4 and /3 variants are meaningfully different speakers sharing a name. Buy on condition and confirmed series, not on the badge alone.
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