The Fifth Element #90

As a film title, Quantizing Hanson Hsu might not rank up there with Kissing Jessica Stein, but we work with what we have to work with. Hanson Hsu is the principal designer at Delta H Design, Inc., an acoustics and architecture firm based in Marina del Rey, California. Though he dabbles in some weird science, Hsu doesn't wear a white lab coat, literal or figurative. He's down-to-earth and personable, with a conversational style that evinces warm wit and a real love of music. At one point in our conversations, he exclaimed, "I get so much joy when things sound good."

Hsu's background includes writing his bachelor's thesis in Creative Sound Technology at SUNY Binghamton, work in sound reinforcement for theatrical and musical performances, teaching in the theater department of Cornell University, and positions as chief engineer at professional loudspeaker manufacturer Westlake Audio and in postproduction at Sony Pictures' Cary Grant Theater, where he worked on Armageddon (1998). DHDI, founded in 1997, has designed or renovated audio facilities for Universal Music Group, Sony Pictures, and others.

In the holiday gift guide in my December 2014 column, I included about $2100 worth of DHDI's Zero Reflection (ZR) products: two ZR Micros ($599 each), which are conventional-looking panels measuring 24" by 24" by 1.25", wrapped in gray fabric, to be placed directly behind the speakers; and three ZR Sample Rate 8 Bit panels ($299 apiece), each 20" by 40" by 0.75" thick and made of CNC-milled MDF, between and above the speakers. According to Hsu, those were the bare minimum needed to achieve an appreciable improvement in my listening room's sound. He was right: The ZR panels improved the sound. Appreciably. I loved it. Indeed, I was taken aback at how much of an improvement I heard, given the small total area of acoustical treatments installed: 24.7 square feet.

The name "ZR Sample Rate 8 Bit" is an inside joke. In response to my query about what digital-audio quantization bits have to do with what seems to me to be a diffusion panel, Hsu revealed that the CNC machine tool that DHDI uses to carve out the panel's unique terraced ridges is 1/8" in diameter: a 1/8" bit. Those ridges end up making each 8 Bit panel look like a 3D topographic model of terraced rice paddies cut into a hillside.

The ZR Micro panels aren't just foam wrapped in fabric. Each weighs about 10 lbs and has a plywood backing. They can be ordered wrapped with fabrics from contract vendors Knoll, Maharam, or Luna. DHDI offers ZR Micros in various Room Packages: the Classic (20 panels), the Plus (40 panels), and the Virtuoso (66 panels). Since the single-panel price is $599, unless there's a package discount, the price of the Classic Room Package would be $11,980, plus nontrivial shipping charges.

DHDI's approach to room treatment, by its very nature, makes A/B comparisons difficult and, it seems to me, of little value. That's primarily because DHDI's 10 years or so of laboratory research, carried out with the assistance of outside scientists, and their in-the-field applications have convinced Hsu that the most problematic early reflections of sound are the frequencies bounced off the wall behind the speakers, which the listener faces while listening: ie, the room's front wall.

Hsu says that it's helpful to envision a speaker's radiations in all directions, while remembering that the sonic output from a speaker's sides, top, and rear—even at listening positions that directly face any of those surfaces—consists of only bass and midrange frequencies, no treble. Reflecting that unbalanced sound back into the listening space can double the initial tonal imbalance. DHDI's method of dealing with the problem of front-wall reflections is to place its acoustical treatments directly against the front wall and the loudspeakers as close to that wall as possible, with, as Hsu said, "the cables that come out of the loudspeakers right up against the acoustical panels." Which means simultaneously changing not one but two variables.

That said, with the ZR Micro panels centered behind my ATC SCM19 speakers and as close to the front wall as possible (see photo), I heard none of the ill effects I would otherwise expect from placing the speakers so close to the wall. With the room reconfigured per Hsu's instructions, the bass was not only tighter, but more powerful and subjectively deeper. This puzzled me, until I figured out that the ZR Micros were likely absorbing energy that would otherwise be reflected back to my ears delayed in time and therefore out of phase with the direct sound from the speakers, and that such destructive interference would thus partially cancel the direct deep bass sound. Ah-ha!

I'd expected the ZR Sample Rate 8 Bit panels to increase the sense of bloom; ie, that more of the room's contribution would be involved in the midrange and treble. But instead of bloom, the result was a sharper sense of focus that added a feeling of richness—an increased sense of power—to Joni Mitchell's voice and piano in the title track of her Court and Spark (gold CD, Asylum/DCC GZS 1025). (I lost track of my mass-market aluminum CD of Court and Spark a long time ago, but through less-than-stellar equipment, even DCC's deluxe gold version risks making the piano sound tinny and Mitchell's voice thin.)

Dealer friend Bob Saglio dropped by to hear what I was making all the fuss about. Bob is something of a room-treatment agnostic for domestic stereo, his skepticism inversely proportional to the area of wall surface covered. He doubted that the sound of an average-size room could be transformed by only 27.4 square feet of acoustic panels. But what he heard impressed him.

Schrödinger's Air Molecule
Schrödinger's Cat is the famous thought experiment in quantum theory that Erwin Schrödinger used to illustrate what he regarded as a weakness of the so-called Copenhagen Interpretation of quantum mechanics (footnote 1). It's not often that an audio-related website brings to mind Schrödinger's Cat, but this paragraph from DHDI's site did exactly that:

"ZR Technology quantizes air at the molecular level. By controlling air (the medium of sound), ZR controls sound before sound can occur, creating a reality in which an air molecule can be in two places at once. [italics added] For the first time, deviations in phase, resonant frequencies, and bass anomalies can be eradicated before they even exist. Fractal-Chaotic Differentiality[–]based mathematics allow for dramatic broadband effects from subsonic to ultrasonic frequencies. Ongoing research continues to uphold the critical postulate that resolution and geometry trump mass and density."

Perhaps a briefer way to put it might be: "There are more things in heaven and earth, Horatio / Than are dreamt of in your philosophy." (Hamlet, I.v)

My response to this is my usual response to audio claims that are unverifiable in some precise particular; eg, the effectiveness of a particular way of braiding or laying the fine wires that make up an audio cable: The thing we are talking about makes its contribution to the system's sound. It is what it is. Usually, I think, an outsider can't tell whether the contribution to the sound made by a new interconnect or a new acoustical panel is because of or despite a claimed design feature of that product. And for me, in the last analysis, which it is doesn't really matter.

A key concept is that DHDI defines the resolving power of an acoustical treatment of a given area by the number of nonparallel surfaces in that area. As the number and thus the proportion of nonparallel surfaces increase, the panel's effect is claimed to change phase, from operating on the wavelength to operating on the air itself, as alluded to in the quote above. Hsu says that anyone who removes the fabric from a ZR Micro panel will see "a lot of nonparallel surfaces in a very complex aperiodic array." The workings of the ZR Sample Rate 8 Bit panels are in plain sight.

DHDI has applied for a patent for some of their technology. The mechanics of that process permitting, a white paper explaining the technology may be posted on their website by the time you read this.

The practical takeaways from my wide-ranging conversation with Hanson Hsu are: For home listening environments, spending about $3500 on ZR acoustical treatments will provide worthwhile benefits—but only for a small listening sweet spot. DHDI's design paradigm for studio environments is to "quantize" the air at the walls to remove all of the walls' effects on the sound, so that you hear only the direct sound from the speakers' front baffles. DHDI's goal is to design out that one-person sweet spot. To achieve that requires covering about 50% of the room's surfaces with ZR Micro panels. With those panels costing about $150/square foot, that gets pricey fast.

Hsu claims that a room fully treated with ZR panels will leave the speakers to reproduce the music as it was actually recorded. He says that a fully treated room does not change the recorded sound "in any human-threshold way you can perceive. You get the room pressurization from the bass that is built into the recording, and the room is not adding or detracting."

Hsu says that DHDI does not claim to have solved "the problem of the two acoustics": the superimposition of the sound of the recording environment on the sound of the playback environment. Rather, he says that that is what DHDI's happy clients are saying. Indeed, the Testimonials page of DHDI's website is full of praise from a wide range of engineers and musicians.

Footnote 1: Schrödinger never actually put a cat in a sealed box with a flask of poison gas that would be broken open by a hammer triggered by a random event of radioactive decay. Just as important, Schrödinger did not create his thought experiment to promote the idea that the cat actually exists in two states, alive and dead, until you checked up on it. Rather, he intended to highlight the problems in trying to apply quantum theory, which describes the behavior of subatomic particles, to objects and situations that occur on a more human scale.

Bansaku's picture

Back in the day audiophiles used to throw up carpet or curtains on the wall behind the speakers. Cheap, sometimes ugly, but effective. :P

Just the facts's picture

Imagine the purity when you eliminate all effects and save money by just taking your speakers outside. Only pesky ground reflections. Sitting atop a tall pole and pointing your speakers up solves that.

Doctor Fine's picture

Domestic audio rooms are sometimes loaded with bad sounding reflected energy which cancels out frequencies, blurs some and creates in general false information to your music playback.
Luck may have it that some rooms are naturally in better shape than others thus leaving most of the work to speaker placement and attention to a clean soundfield (don't put turntables in front of woofers etc).
But other rooms may benefit from sound absorption discretely placed where it kills room reverb.
My current listening room can not tolerate sonex panels up front but a rear wall is out of the sight lines and calling for damping material.
And I wasn't in need of front curtains but they would help a lot up front with killing secondary reflections so in they go.
The well considered purchase of competent lively audio components is half the challenge in getting high quality playback.
The room is the other half.
Considering a good basic system costs over 20 grand the least an intelligent soul could do is spend a few shekels on getting the room to help the sound.
Common sense.