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Review: Delta H Design ZR Acoustics Treatment Philosophy

A Delta H design is an intriguing option for those that desire a "new" way to reach their acoustic-environmental goals.

Any reasonable acoustician will agree there’s more than one right way to effectively treat a recording studio: hard in front and soft in back, tuned bass traps, diffusion mixed with absorption, reflection free zone, dead room, live room, and so on. If you picture the whole of studio acoustics technique employed over the last half century as a pie, someone just added a new slice.

It’s called ZR Acoustics for “Zero Reflections,” and it was invented by Hanson Hsu of Delta H Design a few years back in Venice, CA. The Greek letter delta, meaning “change,” was the only one that stuck with me from high school chemistry. Teenage hormonal vicissitudes alone could explain my identification with the ancient triangular symbol. Post college I was drawn to the delta whenever I found myself desiring a quantum shift in my life or studio work. If traditional acoustics practice is a process of refining tried and true methods, change is precisely what ZR means to the world of studio acoustics.

Mark Holden at The Invisible Studios, Hollywood

It’s not likely Hsu drew the first ZR sketches on a bar napkin, as a.) He loves making visceral sketches with a Sharpie on giant sheets of architectural vellum, and b.) Hanson is not a drinkin’ man, but he is in touch with his quanta. Like Neo, Hanson has a distinct ability to “see” the matrix of sound wave vectors within a space.

Features (or, “Necessity is a Mother”)

In 2005, rockstar mixer Mike Shipley presented his friend Hanson with a challenge: Endow his primary mixing space — which, like many great mix engineers happens to be in his house — with acoustics as good as the finest control rooms in the world (many of which he’s heard) without losing a single inch of square footage or covering the windows or moving any walls in the rectangular living room. “After having retraced the last 100 years of acoustics, I asked myself the question, ‘What are the base concepts of the tried and true models? What acoustic elements have they addressed and what have they not?” says Hsu.

The motivation to not let a client down and the willingness to question the “givens” fermented Hanson’s ideas into a revolutionary new approach that he patented and trademarked as ZR Acoustics. Instead of creating one reflection-free zone at the mix position, herding bass into space-hogging fiberglass chambers, and/or mitigating and compromising, the ideal ZR room is balanced from front to back and side to side with nary an acoustic treatment nor fog machine in sight.

As simple as an apple pie, ZR is made of the everyday construction materials sheetrock, rock wool, caulk, screws and glue inside standard 3.5-inch stud walls and covered flush with cloth. But milk, butter, flour and eggs do not a soufflé make; through ZR’s perhaps revolutionary approach, it’s the unique arrangement of basic ingredients that create a sweet spot the size of several Chefs Boyardee.

I had the opportunity to visit in person the most recent ZR room created for The Invisible Studios in Hollywood. Mark Holden’s all-purpose, two-room composing, tracking, and post mixing space feels like an eerie gray cube: eerie because of the palpable hush and slight sense of vacuum around my ears, and grey because the cloth covering the ZR guts was all in various tones of grey, floor to ceiling, like a Borg cube but without the voices in my head. When it’s your ZR room you can choose whatever colors you want and even have giant images printed on the cloth. Like its name, the studio’s acoustic treatments were invisible.

To demonstrate the movement of a series of his algorithmically aimed, ever-diminishing reflections — the essence of ZR — Hanson deliberately and precisely draws virtual ray traces through the air, counting “one bounce — down 6dB. Two — down 12dB. Three — down 18dB. Four — down 24dB. Five — down 30 … And now we’re into the noise floor before it ever makes it back to your ears.”

In Use (or, “Sounds Like a Record”)

The listening tests proved astonishing. As I scooted my rolling chair back and forth over eight feet from the mix position to the couch in the back, there was very little change in the sound. Off to the side, with my head less than a foot from the wall, I could clearly hear the stereo image, including a hard-panned upright bass. Over the next two hours I moved all over the room and was surprised to hear a consistent stereo image and very little change in the bass, with no flabby build up by the walls. Bass traps are no longer necessary in a space where Hanson has cracked the postulates of orthodox acoustics practice by eliminating the inverse square law. What this means is low stuff don’t build up in the corners no more. ZR’s two main claims — a.) a 5-foot wide sweet zone, as opposed to spot, from front to back; and b.) nearfield monitoring throughout the space appear to be true.

Fast Facts Applications
Studio, home/project studio, broadcast, audio post

Key Features
Sheetrock, rock wool, caulk, screws and glue inside standard 3.5-inch stud walls and covered flush with cloth; custom designs by Delta H Design acoustician Hanson Hsu.

POA (priced on application)

Delta H Design | 310-581-2331 |


I’m sorry if this introduction to ZR Acoustics has piqued you’re interest because it’s likely you now want to know what’s behind the wizard’s curtain. Well, I had to sign a non-disclosure agreement before I took the Redpill and plunged into ZR so I’m just hoping this article hasn’t gone too far. I can tell you it’s simple and elegant and it’s real. It makes sense for world class production facilities or project studios and all shapes and sizes of rooms, whether you’re building from the ground up or installing it into an existing space. Though the building costs are nearly half of traditional first-class studio build-outs, not including Delta H’s design fee, it’s still not cheap. But if enough of us bug Hanson about it, perhaps figuring out how to make ZR acoustics affordable to the masses will be his next breakthrough. I’m an optimist and a dreamer so let me not be embarrassed to prophesy that ZR could do for studio acoustics what the DAW has done for recording.

Considering the total ubiquity of studio environments created within size-challenged domestic spaces, ZR may be precisely the quantum shift in acoustics needed to improve the modern studio model. If ZR came in a kit, everyone would have one. For now, like everyone else, I’ll contact Delta H Design directly with my room dimensions so he can design a room to calculate a seemingly impossible solution within my studio’s (read: bedroom’s) four walls.

Alex Oana is an award wining engineer, who mixes and masters at his studio in Los Angeles.