CAS Quarterly

Winter 2016

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40 W I N T E R 2 0 1 6 C A S Q U A R T E R L Y A Dub Stage Case Study: for measurement and listening tests as soon as possible after most of the messy and dusty work is done. This allows me to begin actual audio measurements, evaluation of surface finishes, and subjective lis- tening tests much quicker in the process to avoid costly changes later. The front of the room and speaker wall was completed first, afford- ing me ample time to evaluate the room. This was very important since the room was not of a typical symmetrically shaped stage and I wanted to make sure the mixing position and client areas had proper response characteristics. Additionally, it allowed me to make sure the alternating wall surfaces, spec'd for acoustical balance, were resulting in a neutral response and the bass traps were doing their jobs suffi- ciently within the boundaries of the room. As we begun to install various equipment on the stage with the speakers being operational, my crew and I got pretty comfortable with the sound of the room and how the room responded prior to install- ing the new woven screen. When it came time to install the new screen, we built and assembled the frame and screen in front of the room. But since our contractor was unavailable to hang it for a few days, we just leaned it against the front wall which, obviously, covered the speakers. Then something amazing happened about an hour later … I'd expected to have some sort of response loss from the speakers being masked by the screen, but much to my surprise, there was no sign of that. I even went back and laid the screen on the floor to expose the speakers again, listened to a bunch of music and dialogue materials, then put the screen back up and I was truly amazed. Admittedly, this is probably the most transparent audio I'd heard on a re-recording stage from speakers covered by a screen. Once this factor was truly realized along with more evaluations, it led to outfitting all the re-recording stages at Westwind with the same type of woven screens. TESTIMONIALS A trusted colleague, Andy Potvin of Dolby Laboratories, carried out voicing the B-chain. Here are Andy's replies to questions about his experience with woven screens. DS: What major differences are you seeing in voicing a room fitted with a woven screen vs. perf screen? AP: The most noticeable difference when voicing a room with a woven screen (especially if the room had a perf screen before) is that the amount of effort required to "push" HF through the screen is dra- matically reduced. The amount of amplifier gain and HF compensa- tion drops significantly, along with a reduction in associated artifacts. DS: Are you observing a lesser degree of audible artifacts attributed to either one? AP: When measuring the system and comparing it to previous mea- surements or, to the system as it stands before re-EQ'ing after a screen change, it is immediately observable that the HF energy passing through the screen is dramatically unimpeded. DS: What is the most significant sound quality change you are observing between them. AP: It is apparent that the noise level of the system tends to be lower "less steam" (extreme high frequencies heard as hiss), the HF tends to seem less brittle (to my ear), and the amount of reflected energy from the screen back into the HF horn is reduced and the associated comb filtering drops significantly. DS: Any other general comments? AP: The benefits of the woven screens are remarkable sonically. If the visual results are suitable for current projection systems, then the choice is clear for the mixing stage. PVC vs. Loom Projection Screens by Dan Shimiaei PREFACE The importance of sound quality is ever so prevalent in today's broadcast, streaming, gaming, and theatrical release environments. As delivery requirement gaps even out for UHD and immersive sound in such disciplines, the quality, transparencies, and closer repli- cation to the eventual audience experience must be recognized. In the recent years, significant improvements in material develop- ment and manufacturing techniques have afforded us screens better suited for mixing in an effort to improve sound propagation with transparency whilst maintaining optimum image quality and unifor- mity. Much is debated in the PVC perforation vs. loom (woven sheet) products with respect to the material properties in maintaining opti- mum image and sound qualities. Many aspects regarding acoustic measurements, light uniformity, moire patterns, longevity, ease of cleaning, outgassing, etc., are scrutinized by both camps. Many manufacturers, interested websites, and bloggers have pored over significant resources to prove claims of superiority in one way or another. The scope of this article is not to take sides with any of the claims nor disprove any of them, but rather explore results from recent user experiences and facility perspectives. BACKGROUND In February of 2015 during construction of Stage 6 at Westwind Media, a decision was made to purchase and install a woven screen. The rest of the facility had been outfitted with a well-regarded manufacturer of perf screens and, prior to purchasing another PVC perf screen, it was decided to look at other screen options. The final decision to purchase a woven screen was made after a few weeks of researching the nature and quality differences between screen materials, testing smaller samples of a few woven screens, and talking to industry peers. Stage 6 was to serve as a testing bed for evaluation of this type of screen since the facility was looking to upgrade three other re-recording stages and outfit them with new screens. A practice I've always followed during the construction or remodel of a re-recording stage is to have the front wall and speakers available Stage 6 at Westwind Media

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