On January 15, we published Diego Estan’s Stenheim Alumine Two loudspeaker review on this site. Diego’s review was extremely positive: “The Alumine Twos’ midrange and treble reproduction was, without question, the finest I’ve ever heard in my room, providing spot-on tonal accuracy combined with transparency that was second to none—I could hear the recordings so clearly it was uncanny.” But Diego also highlighted the inability of the small Swiss speakers to generate enough low bass—something his in-room and our anechoic measurements corroborated. However, when he paired them with his dual SVS SB-4000 subs, Diego experienced the “best sound” ever in his current room.
Shortly after the review was published, we were contacted by Walter Swanbon, who owns Fidelis, a distribution company in the United States. Fidelis doesn’t formally distribute Stenheim products, but the company is the official representative for the brand in the US. Stenheim’s products are all made in Switzerland, where the company is based.
During our several conversations with Swanbon, he provided us with some important details that we didn’t have before the review was published. One was that the Alumine Two carries a list price of $12,950/pair in the United States, which wasn’t far off the $12,913—converted from Stenheim’s price in Swiss francs—that we quoted in the review. But more importantly, he spoke about the bass performance of the speakers and what he recommends his customers do to optimize bass output. This information is not on Stenheim’s site, nor could we find it within any other Alumine Two reviews we’ve seen from other publications.
Stenheim’s speakers—and particularly the Alumine Two—are designed to rely more on wall-boundary reinforcement, or room gain, than most other speakers to adequately present the bass frequencies, explained Swanbon. In other words, they need some bass boost from the room to get a proper bass output level. He also said that the Swiss manufacturer’s speakers sell well in Europe, and the company is accustomed to the speakers being used in smaller rooms than we see in North America. Quite simply, it’s not just that the speakers have less space to fill up with sound, but also that smaller rooms mean the speakers are placed closer to the walls, so you’ll get more bass through room gain—that’s because the closer a speaker is to a wall boundary, the more bass boost you’ll get. European construction differs as well. For example, you can find more concrete in use there, which can provide more gain than the wood-and-drywall construction often used in North American homes, which can allow bass frequencies to “leak” out.
Swanbon went on to explain that he wouldn’t necessarily recommend the Twos to someone who couldn’t set them up as close as they need to be to walls. Unless, as Diego ultimately did, they want to add a subwoofer (or two). And to be clear, I’m not talking about the speakers being just a little closer to walls than in a typical setup—as you’ll find out, the recommendation is that the speakers be placed a lot closer to the wall behind them and, if possible, to the walls on each side. In fact, corner placement can sometimes be ideal for a pair of Twos, as you’ll see. Swanbon also said that they don’t recommend the use of bass absorption panels or traps, because they might diminish the bass. In short, any deep bass reproduced by the loudspeakers should be preserved.
After presenting this information, Swanbon asked if Diego would revisit the Twos in his room using his placement advice. Since our goal is to give the best information we can to our readers, we agreed to assess the speakers the way Swanbon wanted them set up, but with one catch—Diego couldn’t remove his bass traps because they are permanently affixed to the walls. Swanbon was okay with that, because there was no practical alternative.
Just a few days after our final conversation, Swanbon had a pair of Alumine Twos sent to Diego’s place, this time accompanied by Stenheim stands (Diego used his Focal Sopra No1 stands for the January review). We believe that Diego’s account of his experiences as he followed Swanbon’s advice provides valuable insight for anyone considering the purchase of a pair of these unique standmounted loudspeakers.
. . . Doug Schneider
das@soundstage.com
Why not position the speakers differently in the first place?
Some people may be wondering why I didn’t just place the Alumine Two loudspeakers closer to the walls in the first place. There are two main reasons for that.
First, as the SoundStage! Network’s electronics measurement specialist, it should come as no surprise that I do not rely on my ears alone to evaluate speaker performance. I listen casually at first, then critically, all to establish my baseline subjective observations and conclusions. But then I corroborate what I hear with careful in-room measurements. If I proclaim that a speaker is bright, neutral, or bass-shy (compared to typical speakers of comparable size), then I want to be sure that the speaker under review objectively matches these subjective observations (in my own room, of course).
From my listening and the resultant measurements, I figured I was getting the kind of presentation that the Alumine Twos were intended to deliver, and since I didn’t have direct contact with the company, I didn’t feel it necessary to fiddle with placement further. Perhaps you could chalk that up to laziness. On the other hand, I never would’ve gone to the placement extremes that Swanbon recommended on my own, so that factors in as well.
The second reason is related to my primary focus when I review a two-way standmounted speaker, which is pretty much the only speaker type I review—when I’m not busy with component measurements, of course. What I aim to accomplish is the fairest comparative evaluation of the speaker under review. Compared with what? Compared with one of three two-way standmounts I have on hand, at three different price points, that I know measure well. Therefore, I can make a direct, level-matched A/B comparison with a known reference, in addition to comparing with a slew of other two-way standmounts I’ve reviewed in the past.
Since the room’s interaction with the speaker is more responsible for the overall bass response than the speaker itself (yes, the room has that much of an impact), the only way to fairly and consistently compare bass performance from one speaker to the next is to keep the variable of room-boundary effects constant. This is done by making sure that the speakers’ drivers are always in about the same positions in the room (plus or minus an inch or so), from one pair of speakers to the next.
As a result, I have a reference speaker position in my room that, over the years, I’ve selected to optimize not only soundstaging and imaging, but also bass performance and the amount of bass boost that the room provides. The overwhelming majority of two-way standmounts I’ve reviewed yield a satisfying 5–8dB of bass boost in this reference position, whereas the pair of Alumine Twos, with the same positioning, didn’t receive that kind of boost, which I pointed out in my review.
I’d like to think I’m not too dogmatic about my approach, so if a manufacturer makes it clear on their website, manual, or verbally that their two-way standmount is designed to be placed elsewhere to achieve optimal bass performance, I will heed the advice. I’ll listen, evaluate, and measure at my reference position, but also repeat the process following the manufacturer’s instructions and relay my observations to the reader. In the case of the Alumine Twos, I found or received no such instruction, and only learned of Stenheim’s design goals after the review—which is why we’re at this point now.
In-room measurement methodology
All measurements shown below were taken using Room EQ Wizard (REW v5.20.4) and a calibrated miniDSP UMIK-1 microphone. For each measurement, the result shown is an average of nine microphone positions, which includes dead center at the main listening position (MLP) on my single-seat recliner, plus eight other positions within a 2′ radius.
All measurements were taken with both speakers in a stereo pair, swept simultaneously from 10Hz to 20kHz. The plots have 1/6th-octave smoothing applied. Before each set of nine measurements, I targeted an A-weighted 80dB sound-pressure level (SPL) at the MLP using REW’s speaker-calibration pink-noise generator, which is bandwidth limited from 500Hz to 2kHz.
For the purposes of this discussion, I’m defining bass boost as the average SPL between the 50Hz and 80Hz peaks, minus the 80dB reference. I’m also defining bass extension as the low-frequency point where the plot yields -3dB below the 80dB reference (i.e., 77dB SPL).
Bass boost and preferences
My ideal level of bass boost is 5–6dB for a full-range system (extension to and below 20Hz). This is the amount of bass boost I use with my dual subs, which are capable of flat response to about 15Hz. For a system with two-way standmounted speakers without subwoofers (i.e., not full range), I would prefer 6-8dB of bass boost, because I find you need more upper bass to compensate for the lack of super-low bass.
Do my bass-boost preferences reflect what most audio enthusiasts like? I wrote about this in an article called “Bass—How Much Is Enough?,” which you can find on SoundStage! Access. In that article, I wrote about the findings in “Listener Preferences for In-Room Loudspeaker and Headphone Target Responses,” by Sean Olive et al. (Audio Engineering Society Convention Paper 8994). Harman’s research found that the mean preferred bass boost was 11.2dB among untrained listeners, 4.9dB among trained listeners, and 6.6dB across all listeners. Based on this AES paper, it’s fair to say that my preferences likely align with, at the very least, a great many audiophiles. The caveat, of course, is that the paper also found significant variations in bass-boost preferences, with at least one listener preferring a slight bass cut—but I believe these individuals would be in the minority within our hobby.
Listening room and the four speaker positions
My room measures 15′ × 12′, with a ceiling a little over 7′ high. On the floor is carpet over concrete. The room is well damped with broadband acoustic absorption placed at the first-reflection points on the left and right side walls. There is also an absorptive panel between and behind the speakers on the front wall, as well as homemade bass traps in the front corners. I used four different positions to revisit the sound of the Alumine Two loudspeakers in this space.
The first photo shows my typical setup for my Focal Sopra No1 reference loudspeakers. The center of the midrange-woofer driver on each speaker is approximately 29″ from the wall behind (long wall) and about 37″ from each corresponding side wall. The distance between the centers of the midrange-woofers (i.e., speaker to speaker) is about 9′, with the MLP also being 9′ from each speaker.
This same positioning was used for the Alumine Twos when I initially reviewed them, as shown above. In the charts and text that follow, I refer to this as Position 1.
Per Swanbon’s instructions, I moved each speaker back 1′ from their reference positions, but still used my customary 18-degree toe-in angle (i.e., how much each speaker is angled to point toward the listener). This resulted in the midrange-woofers being about 20″ from the wall behind, about 34″ from each speaker’s respective side wall, with about 9.5′ between them. I refer to this as Position 2.
Position 3 had the speakers with the midrange-woofers approximately 14″ from the wall behind them and approximately 32″ from each side wall. The distance between the centers of the midrange-woofer drivers was about 10′. Please note that at this position, the bottom of each stand was about 1″ from the baseboard, and the inside and outside rear corners of each cabinet were only 3″ and 6″ respectively from the wall behind them. I’d never placed any speakers this close to the wall behind them before.
Position 4 had the speakers essentially in each corner of the room, with the midrange-woofers approximately 20″ from the wall behind them and approximately 23″ from each speaker’s respective side wall. This put the distance between the centers of the midrange-woofers at about 11.5′. With this positioning, the distance between the speakers was extreme, so I increased the toe-in angle of each speaker until they were pointed directly at the MLP, to avoid the “hole in the center” effect in the soundstage.
In-room measurement results
The chart below shows the results for Position 1 with the Focal Sopra No1 (green), Revel M126Be (red), and Stenheim Alumine Two (cyan) loudspeakers, all of which are standmounted designs. As I mentioned, I typically set speakers up in this position, so I already had this data for the No1 and M126Be loudspeakers from previous reviews. In the chart, we can see that the Focals yield about 8.5dB of bass boost (the most of the three), the Revels show around 5.5dB, and the Stenheims about 0dB.
What’s very important to note here is that the two comparison speakers were not cherry-picked for their bass output. Instead, the Revel M126Be loudspeakers’ bass-boost result is representative of how most of the more than a dozen two-way standmounted speaker pairs I’ve had in my room have measured. In fact, I’d say the Revels are a bit below average in terms of bass boost. In the chart above, the bass-extension results are 30.7Hz for the Focals, 33.5Hz for the Revels, and 38.5Hz for the Stenheims.
In the chart above we can see measurements for the Alumine Twos in the four room placements: Position 1 (green), with 0dB of bass boost, as shown in the previous chart; Position 2 (cyan), showing 3.5dB of boost; Position 3 (red), showing 4dB of boost, with a less severe null at 129Hz; and Position 4 (pink), which effectively had the speakers in the corners, showing 5dB of boost. So, in Position 4, with 5dB of bass boost and 35.5Hz of extension, the Stenheims managed to produce bass output that fell into the average of what I measure from two-way standmounts in my reference speaker positions (i.e., Position 1).
To better illustrate the bass boost the Alumine Twos were getting by being positioned in the corners of my room, the final chart shows the in-room response of the speakers at Position 4 (red) compared to the in-room responses of the Focal (cyan) and Revel (green) speakers in Position 1. We can see that, when we consider that both the 50Hz and 80Hz peaks are averaged to compute bass boost for the purposes of this discussion, the Stenheims in Position 4 (5dB of boost and 35.5Hz low-frequency extension) yielded a bass response that was quite close to the Revels (5.5dB boost, 33.5Hz extension) in Position 1. So the corner position certainly works to improve the bass response—but how do the speakers sound in these different positions in the room?
Listening impressions for the Alumine Twos at the various positions
As I explained in my review of the Alumine Twos, I found the bass output to be unacceptably low during my listening with the speakers set up in my reference position—the speakers sounded too light and thin. But this time, in Position 2, I found the bass output to be passable, but still lacking compared to most other two-way standmounts I’ve reviewed when they’re placed in the reference position. In Position 3, I found the bass output and extension to approach what many two-way speakers achieve in my room at the reference position—though, with 4dB of bass boost, they were still shy of what I would call satisfying. In Position 4, however, I found the bass output to just reach satisfying-sounding bass levels for a two-way standmount design in my room. I should add that in all the positions, the correct tonality was retained in the midrange and highs.
But it should come as no surprise to any experienced audio enthusiast that there’s a price to pay with these changes in terms of soundstaging and imaging when you bring speakers closer to the wall boundaries. In Position 2, the soundstage was noticeably shallower than in Position 1, but I still found it to have reasonable depth with recordings I typically use for reviews.
With Position 3, the depth of the soundstage flattened considerably (i.e., less apparent space between recorded sounds placed closest to the listener and those further away) and the soundstage height became compressed to no higher than the top of the speaker cabinets. I hadn’t heard this effect with the speakers in Position 2. In terms of soundstage height, with the Alumine Twos or other standmounted speakers set up in Position 1, center-placed vocal images could sound like they’re positioned 2′ or even 2.5′ above the tops of the speakers, which, to me, sounds very realistic. But that wasn’t the case with the Alumine Twos in Position 3.
In Position 4, which yielded the best bass performance, soundstage depth was acceptable but limited, much like Position 2. Soundstage height in Position 4 was commendable, with center images clearly appearing above the speaker plane—though I believe vocalists didn’t sound quite as high as I’d expect from my reference position. However, soundstage width was, as expected, exaggerated, because of the 11.5′ speaker-to-speaker spread. But, thanks to a more extreme toe-in angle, I did not experience a “hole in the center” soundstage. Still, aural images were wider and less defined compared to my reference position. Of course, some audiophiles may enjoy the ultra-wide soundstage effect, so it’s worth trying.
Concluding remarks
In my review of the Alumine Twos, I wrote: “So, if you expect and demand that your two-way standmount speakers have good bass output and extension, then, unless you have a very small room and are willing to place the Twos quite close to the wall to leverage some bass boost from the room, I must urge you to look elsewhere—either that or consider matching these speakers with one or two subs.” After going through this exercise, I think these comments still generally apply, though these charts and listening notes do indicate that if you’re willing to experiment a lot more with placement than with most speakers, you can achieve satisfying bass output from the Alumine Twos alone. I heard proper tonality through the rest of the frequency range, but you would have to assess any compromises associated with soundstaging and imaging due to the atypical placement. And for those whose rooms are even smaller than mine, corner loading might be the best way to get an acceptable bass boost from a pair of Alumine Twos. And in a smaller room, the added room gain could be achieved without sacrificing much in terms of soundstaging and imaging.
In the end, I really do feel that the Alumine Twos sounded exceptional, and quite literally without fault above about 100Hz, which is what I said in my original review. I also wrote that, when coupled with two subwoofers, they provided some of the best sound I’ve ever heard in my room. So, matching the Alumine Twos with one or two subwoofers is still the way I’d lean—even though I’ve shown that, with some experimentation, it’s possible to get satisfactory sound out of the speakers alone. But that’s the kind of thing each prospective purchaser must decide for themselves.
. . . Diego Estan
diego@soundstage.com