EPI Model 100
A little two-way bookshelf that arrived in 1970 with a single capacitor for a crossover and a ten-year guarantee - and promptly became the speaker budget audiophiles measured everything else against.
Overview
The Model 100 was the opening number from a brand-new company. When Audio (May 1970, p.46) profiled the speaker, it described EPI as "a new name to add to the list of speaker manufacturers" and called the Model 100 "a fine opening number." It was the smallest and least expensive of four systems the company launched. All four used identical components in varying quantities: the Model 201 carried two woofer/tweeter modules, the 500 carried four, and the "Tower" Model 1000 mounted one on each surface. The magazine said EPI had settled on the right "combination" for the acoustic balance problem, so it could scale the same driver pair up and down the line.
The cabinet is bookshelf-sized, 21 by 11 by 9 inches and under 20 pounds. Audio (May 1970, p.46) reported that it puts out "surprisingly big sound," runs a little more efficient than units of similar size, and ranked it high among bookshelf systems of the day. The published specs are usable response from 30 to 18,000 Hz, omnidirectional response of 40 to 13,000 Hz ± 3 dB, and an 8-ohm impedance that made it easy to pair with the receivers of the era. Minimum amplifier power was listed at 18 watts rms, with a recommended maximum of 60 watts rms. Those are modest numbers, meant for real-world gear rather than monster amps.
The drivers are where the design gets interesting. An 8-inch high-compliance woofer with a 16-gram voice coil three-quarters of an inch long, riding in a quarter-inch magnetic gap, handles everything below 1800 Hz. Its free-air resonance sits at 18 Hz, and in the acoustic-suspension enclosure it produces sound down to 40 Hz. The long coil and 200% overhang allow a half-inch of excursion. This woofer is built to move air, not to look tidy on a spec sheet. Above it sits a 1-inch tweeter, kept small on purpose so it can disperse high frequencies widely. Rather than build a larger, more directional tweeter, EPI used a miniature acoustic-suspension design that lets the tweeter make large excursions. The top of the magnet structure is hollowed into a small cavity, and the cone works against a quarter-inch air cushion. The voice coil and cone are rigidly interlocked and supported by a rubber-impregnated-cloth surround that damps resonances while leaving the cone free to move.
Then there's the crossover, or rather the near-absence of one. Audio (May 1970, p.46) noted that the network which normally separates drivers from each other and from the amplifier simply isn't present. What sits in series with the tweeter is an 8-µF, 50-volt capacitor, and that's all. EPI's reasoning was that a simple cap sidesteps the phase-shift problems of complex inductive and capacitive networks, and that the woofer is insensitive enough to high frequencies that the combination still yields 18 dB per octave of attenuation. There is very little in there to go wrong.
Each unit shipped with its own frequency-response chart, and Audio (May 1970, p.46) noted the ten-year guarantee, which included shipping. That kind of backing on an $89 speaker, the original list price, was unusual. By the end of 1970, EPI was advertising the Model 100 at that same $89 in Audio (January 1970, p.29), billed in the company's own copy as an "omnidirectional speaker that graphs a pancake-flat response from 40 to 15,000 Hz." Marketing copy is marketing copy, but the independent press largely backed it up. Audio (June 1976, p.47) noted that a leading independent consumer testing magazine had rated the EPI 100 the best speaker for the price, and the company leaned on that endorsement heavily in its mid-'70s advertising. The pitch was "Linear Sound" - a pure, uncolored, natural presentation from top to bottom, with no artificial bass boost to impress the innocent and no treble nuances fading away.
The original isn't the only Model 100. By 1990, EPI had introduced a new version, a two-way Series 2 with a 1-inch wide-dispersion dome tweeter and an 8-inch woofer. It was rated 60 to 20,000 Hz ± 3 dB, with sensitivity of 90 dB at one meter with a 1-watt input and nominal impedance of 8 ohms. That version carried a five-year extendable warranty, a cabinet with rounded front edges finished in textured-slate veneer with a charcoal knit grille, dimensions of 20 by 11 by 9½ inches, and a price of $249 a pair, as reported in HiFi-Stereo (October 1990, p.19). It is a different speaker with a different spec sheet, and buyers hunting the classic should know which one they're looking at.
For collectors, the original Model 100 is the one with the reputation. It's a small, light, efficient two-way that does an honest job with a single capacitor and a pair of well-chosen drivers — the kind of design that ages gracefully because there was never much to fail. The simple crossover means recapping is a trivial job, and the acoustic-suspension woofer surrounds are the usual wear point on any speaker of this age. The included response chart and the ten-year guarantee are period details that make a clean pair with documentation more desirable. It won't fill a large room with seismic bass, and nobody should expect it to — but as a window into what a smart small speaker could do in 1970, it's hard to beat.
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