Hegeman Model 1 omnidirectional loudspeaker The Noise Cone

Sidebar 1: The Noise Cone

Although Hegeman no longer uses his "lily tweeter" in current designs, there are some other systems on the market now whose tweeters work in essentially the same manner, so it's worthwhile to examine just how these devices produce their 360-degree radiating pattern.

A conventional tweeter has its axis aimed forward, and the diaphragm movements push and pull the air in front of it. So how does a lily cone and its ilk manage to produce 360-degree air-pressure waves in a horizontal plane with its axis facing upwards?


Forget for a moment that the lily cone is vibrating, but think of it as the nose cone of an aircraft, moving forwards. The air around it is (relatively) stationary, so as the cone passes through it, the air is first "pierced" by the point of the cone, and is then displaced more and more to the sides as the tapered cone opens an increasingly large "hole" in the air. The result is an air-pressure wave travelling out wards at a right angle to the direction of the cone's movement.

Now, if the cone reverses direction and starts to withdraw, the displaced air moves inwards to fill the diminishing "hole," and a rarefaction wave is produced. Vibration of the cone along its axis creates a series of compressions and rarefactions, radiating in all directions at a right angle to the axis of the cone. Stand the cone on end, with its axis vertical, and you have perfectly omnidirectional radiation throughout the horizontal plane around the tweeter.

Hegeman Laboratories, Inc.
Glen Ridge, NJ 07028 (1973)
Company no longer in existence (2019)

Bogolu Haranath's picture

Can they be used for Dolby Atmos height channels? :-) ........

Bogolu Haranath's picture

They were almost 40 years ahead of time in their thinking :-) .......

John Atkinson's picture
The late Stewart Hegeman was a very influential engineer back in the day. I never heard the Model 1 speaker but a friend in England built a version of it in the early 1970s using, I remember, Wharfedale drive-units. It left a lasting impression on me despite its imperfections.

John Atkinson
Technical Editor, Stereophile

Kal Rubinson's picture

Hegeman also designed speakers for Eico and the Citation amps and preamps for Harman Kardon.

mmole's picture

This classic review reminded me that both of the founding fathers of High-End journalism had the odd quirk of using "dickensian" language. Here JGH jumps right in and refers to himself as "Ye Editor" (Of what? "Ye Olde Stereo-Phile?"). And hardly a Harry Pearson review could go by without his prefacing an opinion with "Me thinks..."

I used to find this irritating but now I must say I miss these two giants.

Bogolu Haranath's picture

JA1 could say "ye (technical) editor" is measuring this XYZ amplifier and, "me thinks" that it has too much 2nd harmonic distortion :-) ........

jimsusky's picture

I regret not knowing about JGH and Sterophile when I was a nascent still-teenaged audiophile in 1978 (soon to be one of tens-of-thousands of BBC monitor/Rogers LS3/5a owners). By the time "we" discovered Stereophile, Aczel and The Audio Critic had started his/its long "sabbatical" and Pearson was still calling your rag unkind names - all too late as far as I am concerned.

This is why I so appreciate these reprints (as HP surely would, if he were above ground.)

So I encourage you to keep doing it - but also to provide some context: JGH refers to "Class A Recommended speaker systems" - a reprint of those (or a link to contemporaneous listings) would be at least interesting if not "valuable".

Not only were Advents and Dynas available then, but also Dahlquists, Maggies, AR's, etc.

I suppose prices were also published in the "recommended" listings?

Having a firm grasp of the obvious and awareness of "the" Consumer Price Index (actually, there may be several of these indexes), I note that JGH listed the 1973 price of this system as $114/pair. This strikes me as downright afforable. The ratio of year-to-year averages of CPI-U (for "urban" consumers) 2019-to-1973 is roughly six - which confirms my impression - the Hegeman 1 sold for the current equivalent of less than $700/pair.

(by another measure, this was about 70 hours at the 1973 federal minimum wage - I later paid about 200 such hour's equivalent wage for my own pair of BBC monitors)

Anyway, thanks for your series of reprints. Again, please consider rolling out those Recommended Components lists.

Ortofan's picture

... actually $114 each, so $228/pr.
The Large(r) Advent was $210/pr in vinyl and $240/pr in wood veneer finish.
The Dynaco A35 was $240/pr.

For comparison, here are the prices for some other contemporary speakers circa 1973:
JBL L26 Decade $260/pr.
Acoustic Research AR 2ax $280/pr.
Bose 901 $525/pr.
Acoustic Research AR 3a $540/pr.
JBL L100 Century $550/pr.
ESS Heil AMT1 $600/pr.
Dahlquist DQ10 $800/pr.
Magneplanar Tympani I $1000/pr.
Acoustic Research AR LST $1200/pr.
Infinity Servo-Statik I $2100/system

To adjust for inflation, multiply those prices by about a factor of six.

John Atkinson's picture
Ortofan wrote:
The price of the Hegeman Model 1 speakers was actually $114 each, so $228/pr.

Thanks very much for the correction, Ortofan.

John Atkinson
Technical Editor, Stereophile

T-NYC's picture

Don Morrison, a friend of Stewart Hegeman, purchased the speaker business when illness prevented its continuance. Don has sustained a steady evolution of the design, and currently offers two remarkable models at MorrisonAudio.com

Bogolu Haranath's picture

TAS was founded in 1973 by Harry Pearson :-) .......

Mark Levinson founded his company an year earlier in 1972, and released the legendary JC-1 pre-amp designed by John Curl :-) .........

Bogolu Haranath's picture

Pink Floyd releases 'The Dark Side of the Moon' album in 1973, which goes on to become one of the best selling albums of all time :-) .......

RH's picture

I got in to high end audio too late to have read JGH, so I'm very happy to see all these reprints appearing here. Thank you!

I really enjoy his writing style and his very direct "tell it like it is" lack of hesitation in discussing flaws as well as pros. (Where the norm these days is usually all the good pointed out so it sounds like a great product, then a final "but lest you think these speakers are perfect..." at the end :-))

Severius's picture

I could launch into a typical BS Stereophile-type review, listing each and every crap recording with which I auditioned the speakers and how they made me 'feel' ["While playing Blind Lemon Nosedrip's vinyl on the Hegeman Model 1's, I could actually feel his spittle spray on my face, and smell his fetid breath..."], but instead I'll take a radical turn and actually tell you how they sounded.

Bass - amazingly deep and tight. Very articulate. In this respect, it contrasted sharply with the bass that was typical of the day - slow, sluggish bass such as that found in the AR3a. Another speaker that came out shortly after the Hegeman were the DCM Timewindows, which had a similar bass quality.

Midrange - There was a big suck out in the mids; probably right around 1Khz. As a result, the speakers never sounded right.

Highs - They used the infamous Philips AD0160T8. Those had a big peak between 12Khz and 14Khz. They sounded sizzly, but without harshness. My young ears liked them. In the Hegeman, they were pointed upward, so some of the treble peak was ameliorated.

If not for the midrange suck out, they'd have been really great speakers.

MCK22's picture

I really enjoy these reprints of Gordon Holt's reviews. I also would enjoy updates in the few cases where the manufacturer, like Ohm Acoustics, are still in business. The case for omnidirectional speakers that JGH makes at the beginning of the review is very interesting and it coincides with descriptions I've read of current omni's.