Stenheim Alumine Three loudspeaker Measurements

Sidebar 3: Measurements

I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the Stenheim Alumine Three's frequency response in the farfield and an Earthworks QTC-40 mike for the nearfield responses. (I measured serial number 20030028.) Owing to the Alumine Three's weight—approximately 154lb—I wasn't able to lift the loudspeaker as high off the ground as I like to do for the farfield measurements. As this meant that the reflections of the speaker's output from the floor were closer in time to the direct sound, I had to window the impulse response data more aggressively than usual, which reduces the midrange resolution of the FFT-derived frequency responses.

The Alumine Three's sensitivity, measured in half-space and without any weighting, is specified as 93dB/2.83V/m. I examined the Stenheim's voltage sensitivity both with the speaker in the usual free-field condition and on its back close to the floor, which will approximate the half-space environment. (This had to be done with care, as the binding posts stand out from the rear panel.) The unweighted sensitivity in both conditions was 94.5dB/2.83V/m, which is a little higher than the specification. However, as I discussed in a paper that I presented to the Audio Engineering Society in 1997, I prefer to publish a loudspeaker's sensitivity calculated with a B-weighting filter (footnote 1), which gives a closer correlation with a loudspeaker's perceived loudness than an unweighted figure. The Alumine Three's B-weighted sensitivity was 91dB/2.83V/m, which is still significantly higher than average.

I used Dayton Audio's DATS V2 system to measure the impedance. Stenheim specifies the Alumine Three's nominal impedance as 8 ohms. I found that the impedance reaches a minimum value of 3 ohms between 38Hz and 41Hz, but the magnitude (fig.1, solid trace) lies above 6 ohms for most of the audioband. The electrical phase angle (dashed trace) is generally low, but the EPDR (footnote 2) drops to 1.5 ohms at 35Hz and to 2.3 ohms between 152Hz and 170Hz; otherwise, it remains between 4 ohms and 12 ohms in the midrange and above. Other than in the low bass and in that narrow region in the lower midrange, this speaker is a relatively easy load.

921STA3fig1

Fig.1 Stenheim Alumine Three, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

There is a strong discontinuity between 200Hz and 300Hz in the traces in fig.1 that suggests the presence of a resonance of some kind in that region. However, when I investigated the cabinet's vibrational behavior with a plastic-tape accelerometer, the panels were relatively inert, with the exception of a fairly strong resonant mode at 770Hz on the sidewalls level with the lower woofer (fig.2). The mode at 770Hz affects only a small area of the sidewalls, has a high Q (Quality Factor), and is sufficiently high in frequency that it should not give rise to any coloration.

921STA3fig2

Fig.2 Stenheim Alumine Three, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of side panel level with the lower woofer (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

The two woofers behave identically below 100Hz but differently above that frequency. The lower woofer, which has a substantial roll surround, starts to roll off gently above 120Hz, while the upper woofer, which has a corrugated fabric surround, crosses over to the midrange unit (fig.3, green trace) close to the specified 300Hz. The blue trace in fig.3 is the summed nearfield output of the two woofers. It has a sharply defined minimum-motion notch at the port tuning frequency of 41Hz, but there is also a notch at 251Hz, the frequency of the discontinuity in the impedance traces. The red trace in fig.3 shows the nearfield output of the rectangular port at the base of the front baffle, which reflex-loads the two woofers. While the trace peaks in textbook manner at the port tuning frequency, a strong resonance is present at 251Hz, presumably due to an internal air-space issue. Although this resonance has a high Q, it is sufficiently high in level that I would expect it to have audible consequences. However, as the resonance lies between the frequencies of two musical notes, B at 247.2Hz and middle C at 261.6Hz (footnote 3), its audibility will depend on the music being played.

921STA3fig3

Fig.3 Stenheim Alumine Three, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with the nearfield responses of the midrange unit (green), woofers (blue), port (red), and their complex sum (black), respectively plotted below 500Hz, 600Hz, 425Hz, and 300Hz.

The complex sum of the Alumine Three's nearfield responses is shown as the black trace below 300Hz in fig.3. It rolls off sharply below the port tuning frequency. The peak in the upper bass, which is due to the nearfield measurement technique, is smaller in amplitude than I usually see, suggesting that the woofer alignment is overdamped. Other than a small peak and dip between 1kHz and 2.5kHz and a slight rise in amplitude between 5kHz and 11kHz, the Stenheim's farfield response, averaged across a 30° horizontal window centered on the tweeter axis (fig.3, black trace above 300Hz), is even. The behavior just above 1kHz might be due to a surround issue with the midrange drive-unit, as is the case with the BBC LS3/5a. Like that classic design, it could be associated with a slightly nasal character, although Herb did not report hearing this.

Fig.4 shows the Alumine Three's horizontal dispersion, normalized to the response on the tweeter axis, which therefore appears as a straight line. The tweeter and midrange unit are offset on the front baffle, and the changes on that side are shown at the front of the graph. The contour lines below the cursor position at 3.46kHz are smooth and evenly spaced, something that contributes to stable, well-defined stereo imaging. The apparent peak centered at 12kHz in the off-axis traces indicates that the lack of top-octave energy in the on-axis response tends to fill in to the speaker's sides. Similarly, the lack of energy off-axis just below that region suggests that the slight rise in the treble on-axis becomes smoother off-axis. Experimenting with toe-in will be useful in obtaining the optimal high-frequency balance. In the vertical plane (fig.5), the Stenheim's response doesn't change much over a +5°/–10° window centered on the tweeter axis, which is 38" from the floor. However, a suckout at the upper crossover frequency develops more than 10° above the tweeter axis. For optimal results, don't listen to this loudspeaker while standing.

921STA3fig4

Fig.4 Stenheim Alumine Three, lateral response family at 50", normalized to response on tweeter axis, from back to front: differences in response 90–5° off axis on other side of baffle, reference response, differences in response 5–90° off axis on tweeter side of baffle.

921STA3fig5

Fig.5 Stenheim Alumine Three, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 15–5° above axis, reference response, differences in response 5–10° below axis.

In the time domain, the Alumine Three's step response on the tweeter axis (fig.6) reveals that the tweeter and midrange unit are connected in positive acoustic polarity, the woofers in inverted polarity. (I confirmed this by looking at the step responses of the individual drive-units.) The decay of the tweeter's step smoothly blends with the positive-going start of the midrange unit's step, and the decay of that unit's step smoothly blends with the negative-going start of the woofers' step. This indicates optimal crossover implementation. The Stenheim's cumulative spectral-decay plot (fig.7) is superbly clean throughout the treble, though some low-level delayed energy is present at 1.2kHz, the center frequency of the small peak in the farfield response.

921STA3fig6

Fig.6 Stenheim Alumine Three, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).

921STA3fig7

Fig.7 Stenheim Alumine Three, cumulative spectral-decay plot on tweeter axis at 50" (0.15ms risetime).

The Stenheim Alumine Three's measured performance indicates that this loudspeaker combines high sensitivity with a generally easy-to-drive impedance and mostly smooth, even behavior in the frequency domain. I was puzzled by the resonant peak in the port's output and by the small peak/dip just above 1kHz, but to be fair, any audible consequences of these resonances will depend on the music being played.—John Atkinson


Footnote 1: See my discussion here and here. The original version of my paper can also be found in the AES E-Library here.

Footnote 2: EPDR is the resistive load that gives rise to the same peak dissipation in an amplifier's output devices as the loudspeaker. See "Audio Power Amplifiers for Loudspeaker Loads," JAES, Vol.42 No.9, September 1994, and stereophile.com/reference/707heavy/index.html.

Footnote 3: See Table 1 here.

COMPANY INFO
Stenheim Suisse SA
US brand ambassador: Fidelis Distribution
460 Amherst St. (Route 101A)
Nashua, NH 03063
(603) 880-4434
ARTICLE CONTENTS

COMMENTS
MhtLion's picture

Sharing my own limited experience. It clearly was one of the most un-colored speakers I've heard in a good way. However, it sounded boxy to my ears. The speakers were driven by CH Precision. Mr. Stenheim was attending the demo himself, so I suppose the set-up was ideal or near ideal. Of course, it could been the room.

tonykaz's picture

I wonder if this Swiss Loudspeaker is as good as my pair of Sennheiser headphones ?

I contend that the Sennheiser HD580/600/650 series headphone is a better transducer system than any loudspeaker I've ever heard ( probably 2X better )!

But 10X Better ? , that is a TALL claim. Even in this HighEnd world of superlative descriptives! Why didn't the Stereophile Editors position this Transducer more prominently on the Front Cover? ( that record player wasn't a believably better transducer, was it ? or have a more believable reviewer ? ( easily doubtable )

I've experienced products that Mr.HR describes, I've found his writing accurate if not conservative in praise. He is Stereophile's top tier Reviewer, for sure, a no bulls#$%^ting reporter, a journalist and NOT a shameless product Promoter.

Somewhere, Stereophile has a Glitzy loving hand on the Controls, keeping a keen eye out for Click Bait gear to Carnival tease the spectator crowd of gawkers. Publishers believe the Front Cover sells. I guess that I'm pleased that this monthly isn't focused on Scandalous and Celebrety front covers about nude swimming Store Owners, Importers, Writers, etc.

So, a solid Aluminium enclosure ( reminiscent of the Celestion SL600 ) , outstanding drivers ( made by whom? ) and a well engineered and auditioned Crossover built of outstanding components . Probably has carefully selected wiring. The $32,000 price seems a Retail Price designed for a 50 point Retail Arrangement ( not Internet direct sales ) and it's manufacturing Cost is 20% of that = about $6,000. It's gonna be a tough Sell, an Alfa Romeo / Vespa type of thing.

Who is in this demographic ?

Tony in Venice Florida

ps. PS Audio is about to release their $20,000 Loudspeaker at RMAF

John Atkinson's picture
tonykaz wrote:
Somewhere, Stereophile has a Glitzy loving hand on the Controls, keeping a keen eye out for Click Bait gear to Carnival tease the spectator crowd of gawkers. Publishers believe the Front Cover sells.

See my discussion on why a magazine chooses "aspirational" products to be featured on its front cover at www.stereophile.com/content/conspicuous-consumption, Tony. Stereophile's worst-selling issue on the newsstand in recent years was one that featured an excellent-sounding but also extremely affordable integrated amplifier from NAD.

tonykaz wrote:
I guess that I'm pleased that this monthly isn't focused on Scandalous and Celebrety front covers about nude swimming Store Owners, Importers, Writers, etc.

Basic publishing wisdom is that the front cover must reflect the content. One of the reasons Fi magazine ultimately folded was that the editor decided to feature musicians on the cover, on the grounds that music was the hi-fi hobby's fundamental driving force. However, the magazine ended up being racked in a newsstand's Music section, where browsers were turned off by the audio content, rather than the technology section, where it may well have found new readers.

John Atkinson
Technical Editor, Stereophile

tonykaz's picture

Thanks, I agree with your responses. I even kinda said so in my comment in the Conspicuous Consumption article .

I didn't mention it but I noticed a typo error in Mr.HR's article leading me to ponder ??? what happened to your outstanding proof reader and re-writer guy? Personally, everything I write is filled with spelling errors and all manner of nonsense ( from interruptions, lapses, phone calls and important messagings ). I have to re-write 4 of 5 times to make any sense. For work, I rewrite work pieces with one day spacings and have a reader check after I become a tiny bit confident ( then restructure the entire piece ). Careful Writing is hard work.

By the way, your Canadian is blooming into something special. I think you've got another good one.

Sorry to hear about your NY,NY falling apart. Louis Rossman, the Right to Repair Guy, is doing YouTube Electric Bicycle Tours of your areas. NY seems to still be the Trashy place I've always known it to be but with Crazy Rents and Covid fears.

The Viral scientists are reporting that everyone will eventually get the Covid Virus. I've already had it, it's no big deal.

Thanks for Writing,

Tony in Venice Florida

rschryer's picture

Very happy you like my writing. I like yours, too.

tonykaz's picture

You are providing critical information to an attentive audience of interested consumers.

Your beautiful packaging of ideas into word constructs are like flavourful Ice cream cones.

You have the vision and the touch.

I'm complimenting your editors here, they deserve applause for turning you loose with word budgets. They discovered a wonderful asset.

Tony in Venice Florida

ps. Stephen King wrote the definitive book on the Writing Process, it's a small book.

robertbadcock's picture

JA;
Been reading 'you' / Stereophile since the hand held digest age of past; can't thank you enough for being so consistent; and as always; the proper English representation.

/r/
Mr. B

John Atkinson's picture
robertbadcock wrote:
Been reading 'you' / Stereophile since the hand held digest age of past; can't thank you enough for being so consistent; and as always; the proper English representation.

Thank you Mr. B.

John Atkinson
Technical Editor, Stereophile

pbarach's picture

RMAF is canceled for this year, and the organizers have decided (and announced) that they won't be doing an RMAF in the future.

tonykaz's picture

Thank you for passing that along, it's Bad news.

PS Audio just spoke of Showcasing their NEW version of the Genesis Loudspeaker at RMAF.

Covid probably killed it and is a catylist for our changing economics.

Amazon & eBay are changing Retail.

Food & Beverage joints are weakening and disappearing.

Tesla has become the Largest Automaker , all without having any sort of traditional Dealer Network.

Schiit is a runaway success despite a shitty name, power switches on the rear and no Retail outlets.

PS Audio is pretty much a Mail Order Specialist.

The internet and individual research seems to have replaced Salespeople for personal sales.

Streaming seems to be replacing CDs and Radio.

We've all lived like Amish for the last 11,000 years, then Ben Franklin discovered Electricity and we went on a tare of discovery.

Who can see two years over the Horizon? Phew

RMAF was the intellectually finest Audio Show I've ever been to or displayed at. The Seminars were outstanding. RMAF was the Good ole days!

Covid killed an institution,

I'm gonna miss it!

Tony in Venice Florida

thatguy's picture

The internet and individual research seems to have replaced Salespeople for personal sales.

For the lower to mid priced stuff it seems youtube pitchmen have replaced the individual salesperson. It is normal now to have items that are hyped by a youtube personality sell out and the comments are full of "I bought this based on your recommendation" notes.

Many of them have achieved what in store salespeople dream of; the customer thinks they are their friend, giving them friendly advice.

Jason Victor Serinus's picture

Oops. Comment removed due to redundancy.

Axiom05's picture

{The Viral scientists are reporting that everyone will eventually get the Covid Virus. I've already had it, it's no big deal.}

Tony, glad COVID was not a major issue for you. There have been over 700K deaths in the US from this virus and I doubt the surviving relatives would agree with you. Don't be so insensitive, maybe you need to spend a bit longer on writing your posts. Having an uncle who came damn close to dying from it, I'd say that it is a big deal. Besides, your comment has nothing whatsoever to do with the topic at hand.

Ortofan's picture

... both Stenheim and Harbeth.

Does Walter Swanbon agree with Alan Shaw that the bespoke plastic formula Harbeth developed is the ideal midrange/mid-bass cone material?

If so, does that then suggest the Stenhiem speakers, with their paper cones, are inherently inferior?

Or, is Fidelis handling the Stenheim line in order to offer products to customers for whom even the top Harbeth model is too inexpensive and/or want a more modern cabinet styling?

Jason Victor Serinus's picture

Every one of your questions is based on your own personal value judgments. Why don't you call Fidelis A/V and ask them?

jason

Ortofan's picture

... consider doing some investigative reporting.

If a given importer/representative fully accepts the design philosophy of a particular speaker manufacturer - plastic driver cones and thin-wall wood cabinets, for example - how do they convincingly also act as importer/representative for another speaker manufacturer with an entirely design philosophy - paper driver cones and aluminum cabinets - without giving the appearance of being at least somewhat disingenuous?

If one company's set of design choices - based on the outcome of government-funded and BBC research programs, for example - is deemed correct, then can another company demonstrate the basis that supports the appropriateness of their entirely different set of design choices - and successfully refute those of a competitor?

Jason Victor Serinus's picture

Your statement presupposes that there is only one "right" way and one path forward, and that a distributor's personal beliefs and philosophies are reflected 100% in the products they sell. Neither is true. Nor should it be otherwise.

You, of course, are free to believe otherwise. I shall leave you to your beliefs and withdraw from this conversations.

Ortofan's picture

... in which (in the first three panels) the same salesman is shown stating to three different customers about three different speakers that he has a pair of those speakers in his own living room.
The last panel shows the salesman, now at home, sitting in a recliner and watching TV, while visible in the background are pairs of each of those three speakers, still in the boxes.

supamark's picture

The distributor is a smart businessman who realises that Stenheim and Harbeth make speakers that sound very different and appeal to different tastes, and simply wants to serve a wider market.

Occam's razor, you should use it more often.

Mark Phillips
Contributor, Soundstage! Network

Ortofan's picture

... the purpose of hi-fi audio equipment to recreate the live event as closely as possible - and if two speakers sound very different, can they both be correct - or is it to appeal to a given listener's variable subjective taste?

It seems that, once again, we return to the question posed long ago by David Hafler: Should a piece of audio equipment be "pleasant sounding, or should it be accurate even if accuracy is not as pleasant?"
https://www.stereophile.com/content/manufacturers-comment-0

Jason Victor Serinus's picture

The purpose of good audio equipment is to reproduce, as faithfully as possible, what the artist(s), producer(s) recording, mixing, and mastering engineer(s) want us to hear. That is different from "recreating the live event." Besides, the "live event" sounds different in different environments. There is no absolute sound.

Anton's picture

Everyone has their own absolute sound, which I will define as searching for 'personal sonic verisimilitude.'

You do it, too. Your reviews are chock full of references to the absolute sound of live un-amplified music occurring in real time and space.

You can tell in a split second 'real vs. reproduced,' the absolute sound is your cue.

__

That being said, we can then start to argue about whatever else the what the artist(s), producer(s) recording, mixing, and mastering engineer(s) want us to hear.

Isn't that as ineffable as the absolute sound?

Jason Victor Serinus's picture

That's all that need be said.

Ortofan's picture

... absolute sound source available to you?
What about the sound of the voice of someone known quite well to you, such as that of a family member?

Try making a recording, using a good vocal microphone, of that individual speaking.
If possible, make the recording while outdoors to approximate anechoic conditions.

Now, play the recording back on your audio system.
How faithfully does the reproduced sound correspond to the sound of that person speaking to you live?

Also, you might record your own voice (or perhaps your whistling) and ask the family member to make the same comparison.

Know anyone who plays an acoustic (unamplified) instrument?
Try recording them and then evaluating the reproduced sound.

Anton's picture

Check out the Stereophile demonstration discs. They are great fun and have a section comparing different microphones!

The choice of microphone greatly impacts how someone/something sounds on my system.

The moment you told Jason that the absolute sound can be captured, you left behind the absolute sound.

I don't mean that in a pejorative way, I'm just saying that even the most transparent bottle can't allow you to have the same firefly experience as enjoying unbottled ones.

Seriously, that Stereophile Demo disc will amaze you.

___

I might go out on a limb and venture to guess that JVS has spent more time listening to the true absolute sound than 99% of other reviewers. I've had the fun opportunity to 'watch' JVS listen, both in my days in the Bay Area Audio Society and at shows: he has a killer ear and a rock solid live unamplified music foundation. (Not saying that, like all audiophiles, he sometimes might hear things that aren't there...;-D....but, man, don't we all.)

This is an eternally fun topic, cheers to all audiophiles today! Here we are alive and able to argue about a luxury such as the wonderful time we spend listening to music, on the Hi Fi.

Ortofan's picture

... "There is no absolute sound."
I suggested that he could use the voice of a family member as the "absolute sound".

Of course some microphones are more neutral than others. Sometimes the choice of microphone is used to deliberately color the sound. I've used B&K microphones for four decades, so I'd suggest using the DPA 4011.
Which microphone would you suggest using for a vocal recording?

Although, to use your analogy, while even the most transparent bottle can't allow you to have the same firefly experience as enjoying unbottled ones, perhaps we can find a "bottle" that is sufficiently and satisfyingly transparent such that the experience of looking through that bottle is close enough to the "unbottled" experience for those times when we can't be present at the live event.

supamark's picture

You asked why a hi-fi dealer would carry gear from different mfgs that didn't have the same house sound or look. The simple answer is, to make more money - which is essentially what I told you. The rest is your own need to stir the pot by continually "just asking questions."

Mark Phillips
Contributor, Soundstage! Network

Ortofan's picture

... the question I asked. Reread my post.

JHL's picture

...although it inadvertently exposes the bias that supposes that the goal of speaker A is the often-malformed abstract that since there IS some magical way to render "accurate" sound, Speaker A must be doing so. Or amplifier X and so on.

There IS no accurate sound. There is no basket of specs and parameters with which to reproduce it. There is no single way to design and make a speaker. Therefore, "accuracy" is as much a fallacy as is the projected your-***-is-colored nonsense from self-styled, un-eared "objectivists" whose only metric is a third party projecting a datum and then applying it to presumed sound, blissfully ignorant of everything else the speaker is doing. Likewise all audio components.

If Speaker A not only can't do this supposed accuracy objectivists go on about after they've been biased by data, and if Speaker B isn't allowed into the fold, then the problem is obvious.

It raises the question why we're doing audio. Why are we doing audio? Comments threads? False projections? Debate? Begging the question about "accurate" speakers - when there is none - is ironically the way to generally get lesser sound.

Simon Moond's picture

I am a bit surprised that someone with the audio reviewing experience, as Mr. Reichert surely has, would think that paying 10x (or any other multiple), would yield a sonic improvement commensurate with that 10x money spent.

Once one reaches a certain level of audio performance, spending double, triple, or even 10x the money will never yield that same amount of sonic improvement. At that point, spending 10x the money, will yield improvements in smaller increments. It is up to each individual to decide, at what point, the large expenditure is worth the small improvements.

After all, there are quite a few people out there, that wonder if spending 10x more for Herb's LS3/5a, over their ELAC Debut B62, will get them 10x the improvement.

I would say "no" to both situations. But that does not mean that either price increase is not worth the money.

Anton's picture

I would not argue with that conclusion one little bit!

The premise, I guess, is that the Falcons are 'worth' 3300 bucks in the first place.

I thought Herb's review was pretty terrific.

The only downer in the review was this part: "I never imagined how much previously undelivered recorded information the Stenheim Alumine Threes would bring into my room."

It made me a bit sad to think Herb had to live to his current ripe old age of 39 to hear how much 'undelivered recorded information' he's been missing all this time. I'd be pissed, I think.

I once read a review of some Stax headphones wherein the reviewer mentioned he had managed to go from 1960 to present day without ever having heard a pair before.

Even our most peripatetic and cosmopolitan reviewers can wash up on unfamiliar shores!

ok's picture

and if anything makes me like it even more.. then so be it.

Anton's picture

I wonder if it would be fair to say we choose our systems based on how they allow us to editorialize the sound to our liking.

Cheers, man.

robertbadcock's picture

I miss the Absolute Sound.

I'd like to think that JGH and HP are having an amiable argument; with responses a month apart; while sharing a port.

.

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