Focal Aria 936 loudspeaker Confounding, Cables, and Room Acoustics

Sidebar 3: Confounding, Cables, and Room Acoustics

In designing an experiment, one of the essential requirements is the avoidance of confounding. If you want to determine the effect of a single variable, you must change only that variable, and keep everything else constant. If you change more than one variable (unless it's part of a more complexly designed, multivariable experiment), then any differences in outcome may be due not to the variable of interest, but to the other, confounded variables.

This concept is relevant not only to scientific research but to conclusions drawn from everyday observations. A typical example in audio involves listening to a system featuring a particular speaker in one room at an audio show, then listening to another speaker in another system in another room. If your focus is on speakers, it's tempting to attribute any sonic differences to the speakers, but the comparison is rife with confounding. Unless the two systems use exactly the same components, each component is a confounded variable—as are the rooms, the acoustical treatments (if any) in each room, the positions of the speakers, the position of the listener in the room, the amount of time each system component has had to break in/warm up, the number of people in each room, and a variety of psychological factors, including the listener's mood and level of aural fatigue (the latter an important factor of show conditions), etc. It is in consideration of these potential confounding factors that I tend to be cautious about drawing conclusions about the sound of specific audio components at shows.

While the methodology used in the subjective reviews of audio gear may not satisfy the most rigorous scientific criteria, I think most reviewers do their best to ensure that their conclusions represent the sound of the component being reviewed, and not the result of a failure to eliminate confounding. Whenever I get a new component to review, I make it a point to keep the rest of the system the same. But sometimes there are obstacles to this practice. If the component is a speaker, the designer or marketing rep may want to send me cables that they've found work particularly well with that speaker. I can appreciate that they want their product to sound its best, but changing the cables involves obvious confounding. Of course, I could listen to the speakers with my usual cables as well as the ones the speaker designer recommends, but I'd then be reviewing the cables as well as the speakers, and I don't want to go down that road. Unless there are solid technical reasons for not using my usual cables—eg, the speakers need to see a specific characteristic cable impedance—I prefer to stay with cables whose sound is familiar to me.

For several years now, I've standardized on Nordost Valhalla speaker cables, interconnects, and power cables. Are they the best? I can't say. There are a lot of cables out there, and I've listened to only a few of them (albeit some other highly regarded ones). I haven't heard anything that is more transparent to the signal and more revealing of musically relevant sonic details than the Valhallas. By staying with them, I know that at least there has been no cable change that would involve confounding—and while the Valhallas are more expensive than the cables likely to be used with a speaker such as the Focal Aria 936, I'm pretty certain that my cables weren't limiting the speakers' performance in any significant way.

But no audio product line stays the same indefinitely, and during my time with the Aria 936 word came that Nordost was replacing the Valhallas with the Valhalla 2s, and the company offered to swap my loaner set of original Valhallas with Valhalla 2s. It made sense to move to the latest models, but I wasn't about to change cables mid-review, so I delayed using the Valhallas until I'd finished listening to the Aria 936. Once the formal listening was done, I was ready to swap cables. And since the review was essentially finished, confounding was no longer an issue.

And then I thought: As long as I'm making changes, I might as well bite the bullet and undertake the long-overdue renovation of my listening room. So out came all the equipment, CDs, and LPs, to be temporarily stored in other parts of the house, and our renovation contractor set about removing the wallpaper (some of it three layers deep), painting the walls and ceiling, installing crown moldings (which, as well as being attractive, may have some sonic benefits), and replacing my hodgepodge of CD racks with floor-to-ceiling shelves painted the color of the walls. Another change that I expected to provide acoustical benefits was the replacement of two sets of louvered doors that lead into a large closet on one side of the room. The replacement doors are much more solid, and are marketed for their soundproofing properties.

The hardwood floor was refinished, and the extra-thick rug that had covered most of the floor (and presented a challenge to speaker cones and spikes) was replaced with a smaller one that would allow speakers to be placed on the part of the hardwood floor now left exposed. When all the equipment, CDs, and LPs were brought back, I also returned the pair of Tube Traps to the front left and right corners, and Cathedral Sound resonance-controlling devices to the room's top four corners. Finally, part of the wall behind my main listening seat was covered with sound-absorbing panels from Vicoustics. I'd previously used packing foam for this purpose—effective, but not exactly decorative. The photo shows my listening room after all these renovations. I don't have a "before" photo, but if I did, trust me—you wouldn't want to see it.

I still had the review samples of the Aria 936s, and of course I had to hear what they sounded like in the revised environment and with the new Valhalla 2 cables.

In a word: great! And this was without the speaker spikes being extended, and without having gone to any special trouble to set up the speakers just so. The sound was more open, more dynamically free, more lively, and perhaps a touch brighter than before, but still nowhere close to being too bright. Keeping in mind the multiple confoundings represented by the changes in cables, doors, carpet, wall surface, molding, and furnishings, I can't say what role each played in producing the differences, but the combined effect is a significantly more realistic sound—and my greater musical enjoyment.—Robert Deutsch

US distributor: Audio Plus Services
156 Lawrence Paquette Industrial Drive
Champlain, NY 12919
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Rick Tomaszewicz's picture

You suggested perusal of Recommended Components for a good matching amp. Perhaps it's time for Stereophile to develop an app which matches recommended or reviewed components based on reviewer-observed synergies? Now that's an app that could save our hobbyists a lot of money and frustration! You could use all the usual criteria such as speaker efficiency v.s. amp output, but also provide guidance on frequency balance matching, i.e.; soft phono preamp with bright cartridge.

remlab's picture

..has that old Focal/Wilson 20khz resonance. Compensates for us old guys hearing.

Allen Fant's picture

This newest series are on my radar to demo. In the past, I really liked the 918/928 models.

I am interested in the new driver material.

eriks's picture

Unfortunately a lot of listeners point the Focal's straight to their ears. This might be good for many speaker's, but not for the Profile's which shared a similar tweeter design and resonance. They have a more neutral tonal balance and image much better with the speaker's toed in as little as possible.

eriks's picture

Hey Robert,

You might have been snookered a little by Focal. While they make good stuff, the al/mg tweeter with a poron surround has been around for about a decade. It's not so new. Still sounds good though. :)



Vlasto's picture

Focals are actually paired very ofter with German T+A...very pleased combination ...


latinaudio's picture

Where did you saw that combination? I have a pair of Focal Electra 926 plus T+A electronics and the highs still sizzle, although the bass performance got better...

growboxguy's picture

On a whim I just purchased a set of Aria 926 for the crazy price of $1799 shipped, brand new from an authorized reseller. I had to take the white color for that price but hey, I will work with it.

My question is will these mate well with my Bryston 3b SST? I listen to mainly rock at high volumes, I use a subwoofer crossing at 60 hz so low end wont be a problem. My system consists of a Bryston BDP-2, Teac UD-301 DA converter, Yamaha CX-A 5000 preamp, Bryston 3b sst for mains and an old school Classe Audio DR-10 on a pair of JL Audio 12w6v3 in a custom sealed enclosure.

Thanks so much!