Hegeman Model 1 omnidirectional loudspeaker

Ye Editor had his first exposure to a true omnidirectional speaker system 15 years ago, while he was employed as chief equipment tester for High Fidelity magazine. The speaker was a most unusual-looking device for its time, being roughly a foot square and standing 3 feet high, with a “cube” of grille cloth at the top like a cupola. Inside the cupola was an 8″ woofer facing upwards. Directly above it was the weirdest-looking tweeter you ever saw.

Instead of a cone, it had what looked for all the world like a large, white lily sticking up from the voice coil, and close inspection revealed fine blue ruled squares on the “lily,” earning for it the nickname by which it is remembered: “the ledger-paper tweeter.” That system, designed by Stewart Hegeman and later produced by EICO as their HF-S2, was memorable for two other reasons, too. It was the most astonishingly spacious-sounding system of its size that anyone had ever heard, with a truly hair-raising sense of depth even when heard from a distance of a foot or so. And it produced the best stereo imaging and center-fill of any hitherto-available system. It was a commercial disaster, partly because of poor promotion, but mainly because the production-line samples, in marked contrast to the preproduction prototypes, were alarmingly variable in sound and had severe midrange colorations. But their stereo performance left a lasting favorable impression that our experience with more-recent omnidirectional systems has done nothing to change. All of which made us immensely curious about Stew Hegeman’s latest design.

The Hegeman 1 (the logic of that chronology escapes us) differs from the HF-S2 system in several respects. The woofer, still facing upwards, is now angled slightly forwards. The lily is gone, and in its place is a small upward-facing, forward-angled dome tweeter, with a hemispherical underside to reflect the woofer’s sound waves outwards. And like the HF-S2, the Hegeman 1 has the rear surface of its cupola closed off with a solid panel so that the compartment is open on four surfaces only, but the loss of rear radiation does not seem to impair, and probably improves, the behaviour of the 360-degree radiators in the speaker (by suppressing delayed reflections from the room wall behind the systems).

The only thing that distressed us initially when we read the manufacturer’s literature for the Hegeman 1 was its description of the woofer-loading arrangement as a “multi-resonant system.” We have heard such systems in the past, and the best thing we could say about them was that they did what they were claimed to so. They resonated, and the resonances were both multiple and painfully audible as smearing, hangover, and gross colorations.

We should have given Mr. Hegeman more credit. His multiresonances are all at low frequencies, where response irregularities are less noticeable than in the upper ranges, and they appear to be very well damped (just as it is possible to damp out the resonances in any other kind of speaker system). The result, to our surprise, was some of the deepest, tightest bass we’ve heard from any system of comparable size or price.

Sweeping an oscillator through the Hegeman 1’s range revealed signs of its “multiresonant” bass loading, as a series of equally-spaced peaks and dips of rather substantial magnitude, very similar in fact to the low-end bumps encountered in most cassette recorders, but with broader humps and much narrower dips.

The bass range sounds considerably smoother when reproducing music than when sweeping an oscillator slowly through the bottom range, for our ears tend to judge low-end response largely on the basis of the heights of the peaks, and narrow dips are not noticed at all except on those very rare occasions when a bass note’s frequency coincides exactly with that of a dip. The lowest-frequency hump occurred slightly above 30Hz, and since this was only a few dB down in level from the output at middle frequencies, the system (or a pair of them, at least) was able to maintain subjectively flat response down to about 50Hz and usable response down to an astonishing 27Hz!

Our subjective response curve (fig.1) reflects how a pair of Hegeman 1s sounded to us when reproducing program material (rather than oscillator sweeps). As shown, they were not entirely free from coloration. The overall balance was generally good, although with a rather soft and somewhat distant-sounding quality. Highs were free from conspicuous peaks, but were judged to be somewhat rolled-off in comparison with the best high ends we’ve heard. The result was sweetness but a mild shortage of “snap.”

Fig.1 Subjective frequency response of the Hegeraan 1 speakers when listening to program material. Oscillator sweeps revealed deep but narrow low-frequency dips.

Middle highs were somewhat accentuated, causing a touch of hardness which tended to exaggerate the differences between the relative hardness of different amplifiers and preamps. The presence range, on the other hand, was slightly depressed, which accounts for the system’s distant perspective and its overall quality of “richness.”

Two mild peaks were observed in the low-end range, but neither was of sufficient magnitude to be of significance except when, by coincidence, a standing wave in the room happened to occur at the same frequency. Unlike most small systems, though, the low-end range of the Hegemans is essentially linear in most locations in most rooms, which means they sound thin in rooms which have trouble supporting low end. (Most compacts are thin in typical rooms and are even thinner in bass-shy rooms.)

When bottom-thinning does take place, it does so through the entire low-frequency range rather than just at the extreme bottom, so although the overall balance is affected (and tweeter-level adjustment doesn’t help—the crossover is too high), the system’s deep-bass response relative to the upper bass is virtually unaffected. Oddly, though, what is more affected is the middle range, which develops a perceptible “aww” coloration. And since a certain proportion of recordings also have some of the same coloration, the net result is an apparent enhancement of the differences between the sound of different recordings. This quality of “selective fidelity,” whereby a speaker seems to point up differences between recordings is often held up as evidence that the speaker is more “analytical” and is thus a more-accurate reproducer. Sometimes this is the case, but not always, because it can stem from tendencies on the part of the speaker to exaggerate certain aspects of the program material, and this is not an aspect of fidelity, but is rather a sign of imperfection in the speaker system.

We mentioned the tendency for the Hegemans to spotlight differences in the hardness of sound from different amplifiers. Their low end, too, is moderately affected by the power amplifier characteristics, being a bit heavy and loose with moderate-powered amplifiers of moderate damping factor (like the Audio Research units), and slightly sparse and taut with high-powered high-DF amps like the Crown DC-300A. This suggests a way of coping with the effects of the listening room on the system’s low end.

Efficiency was quite low—estimated at around 1%, so the manufacturer’s recommendation of 20 amplifier watts per channel minimum is no idle jest. A maximum rating of 25 per channel, though, is ridiculous. We would recommend 60Wpc and a modicum of restraint in use, or a couple of hundred per and 1¼-amp fast-acting fuses in the lines. Since it is, however, just a bit ridiculous to use a $700 amplifier to drive a pair of $114 speakers, we would recommend the Citation 12 as being the ideal driving amp for the Hegemans.

We were not surprised to note that the Hegeman 1’s strongest asset was its tremendous sense of spaciousness. Like the original Hegeman system, you have the feeling of listening through the Hegeman 1s rather than to them, for which reason they are ideal speakers for use in small listening rooms or in difficult decor situations where it is impossible for one reason or another to sit farther than a few feet from the speakers. Like other omnidirectional systems, you can get full stereo spread even when listening from the left of the left-channel speaker (or vice versa). Because of their rather distant sound, though, they are likely to sound too remote if listened to from a distance of more than about 10 feet.

One thing we did however find the Hegemans to be ideal for was the rear channels of an ambient stereo system, which calls for just those qualities in which the Hegemans excel—spaciousness, omnidirectionality, and a feeling of distance rather than of immediacy. Because of their rather erratic impedance characteristics, though—due to their multiresonant bass loading—we recommend driving them from their own stereo amplifier (with an appropriate decoder) rather than via a Hafler-type “passive” decoder which connects the ambience speakers between the front-channel amplifier outputs.

We did most of our listening to the Hegemans as normal stereo speakers, and after having lived with them for several months, in different rooms and with a wide variety of program material, we would describe them as spacious, rich, and despite their minor irritations, easy to live with. But that breath of life was never there. Most musical instruments just didn’t sound quite real to us, and we were always at least vaguely aware of listening to reproduced sound rather than to live music. (The Hegemans are in good company in this respect; we have observed the same shortcoming in some of the Class A Recommended speaker systems, which are listed because they are state-of-the-art components in some other respects.)

If we were shopping for speakers in this price class, we would probably choose the Dyna A-35s because, to our ears, they sound more alive than either the Hegemans or the large Advents, and they are more easily able to fill a moderate-sized room than either of those, with amplifiers of the power one would use with them. There are some nice things about the Hegemans, though—their spaciousness and their remarkable ability to provide adequate center fill despite wide spacing—and although they are not our cuppa tea, we have heard from too many satisfied Hegeman 1 owners for us to be able to dismiss these speakers out of hand. Our suggestion, then: Audition a pair of Hegeman 1s for yourself.