Welcome back to our series on immersive live sound. The June 2020 issue of FRONT of HOUSE featured Terence Caulkins, PhD offering his expert input on setting up pre-production systems for immersive sound. On a related note, I have been working on some studio monitor design concepts for pre-production of live-sound immersive programs. Existing information on that topic seems to be scarce, so I turned to two experts from leading manufacturers d&b audiotechnik and L-Acoustics, regarding setting up immersive pre-production systems.
Pre-Production for d&b audiotechnik Soundscape, By Nick Malgieri, d&b Advanced Systems Specialist
There are three main methods for pre-mixing Soundscape shows. These include:
- Offline without a DS100 Signal Engine (without auralization). This can be accomplished by using: d&b’s free R1 software; QLab software (Pro License required); a DiGiCo SD-Series console; an Avid S6L-Series console; or DAW software equipped with the Soundscape plug-in. Once the software control is programmed, an Ethernet cable can be connected to d&b’s DS100 onsite to enable real-time rendering of Soundscape’s En-Scene and En-Space parameters to the “show” speaker system. All delay times are handled by the DS100, so very little manual programming will be required.
- At one of 17 d&b demo facilities across the world (see full list at dbsoundscape.com).
- On a temporary speaker system with as few as four speakers (most common). A temporary speaker setup can be assembled in your own facility and controlled via the DS100 signal engine. The temporary setup can be as small or as large as you require with as few as three speakers for 180° systems and five speakers for 360° systems. Speakers do not have to conform to a specific arrangement or other specification.
Fig. 1 shows a fairly elaborate demo system, including overhead speakers. For a typical control room-sized environment, three E6 or 8S speakers are more than sufficient to audition 180° systems. Once the show is programmed and mixed, the DS100 can then scale the existing parameters to the “show” speaker system automatically. This includes handling multiple types of speaker zones including front fills, delays, overhead speakers, mono out fills, etc. All delay times are handled by the DS100, so very little manual programming will be required onsite. Bjork’s studio in Iceland was temporarily outfitted with a Soundscape system in order to prepare content for the tour. A total of 15 d&b E-Series speakers were chosen to allow for small groups of people to enjoy the auralizations. Once the show is mixed and programmed, the DS100 makes it easy to adapt to differing speaker arrangements on site.
‡‡        Adapting a Touring Show to New Venues
When touring, it’s common that speaker positions, quantities and orientations have to change from venue-to-venue. This is handled easily be modifying the speaker arrangement in ArrayCalc and then reloading the system into the DS100 engine. This allows the processor to automatically render the existing show parameters for the new speaker arrangement. If object positioning is controlled externally — DiGiCo console, QLab, tracking system, etc. — the object positions can be automatically scaled to match the geometry of the new venue in order to avoid reprogramming the external controller). The Kraftwerk tour had three differing venues with wildly differing speaker arrangements. Speaker position, orientation, quantities and models can be easily changed. The processor will automatically re-render the signals to accommodate the new speaker arrangement.
L-Acoustics L-ISA Auditoria and Pre-Production Workflow, By Sherif El Barbari, Director of L-ISA Labs
L-ISA Auditoria is a predetermined system designed to exacting standards to guarantee the natural, intimate spatialized experience of L-ISA Immersive Hyperreal Sound technology.
A mobile or permanent L-ISA Auditorium can be deployed to support mixing sessions, trainings or demonstrations using audio and video tools. We developed L-ISA Auditorium packages available in two versions, Syva or X Series, which are both are suitable for different types of spaces and tasks. Over the past months, we’ve started deploying L-ISA Auditoria all over the globe. The first one opened at Sonoruss in Moscow in September 2019, followed by further auditoria in Western and Eastern Europe, North America, Asia, South Africa and Scandinavia, just to name a few.
Along with the deployment, we released accompanying guideline and recommendation documents to support the installs. Among the tasks carried out in these venues are pre-production mixing and programming sessions to prepare for events or tours profiting from the L-ISA technology.
Historically, pre-production systems utilized L/R speaker configurations, fed by the stereo mixing bus of a console, allowing to evaluate the mix. In a real venue — theater, arena, concert hall or outdoors — a so-called stereo mix is correctly perceived only by a very limited number of the audience, namely the few in the center, between the L and R speaker arrays, referred to as the “sweet spot.”
With L-ISA, the sweet spot is expanded to the majority of the audience and the mix is perceived in the same way as our natural hearing perceptions works. It allows people outside of the privileged sweet spot to enjoy the performance in complete clarity.
To ensure that the pre-production for an L-ISA event happens under similar conditions as in the actual venue, the mixing engineer must use a scaled down speaker system in order to create an object-based mix using the creative tools of L-ISA.
The first step to preparing an L-ISA project is to create a speaker system design in Soundvision, L-Acoustics’ proprietary 3D simulation software. The design considers all aspects of the sound reinforcement system to fulfill the required specs for the event. The optimized loudspeaker design then is imported into the L-ISA Controller, our intuitive control software of the L-ISA technology and the gateway to numerous creative interactions with the system.
Based on the Soundvision design import, important parameters become available for use in the L-ISA Controller software. Parameters include:
- Physical speaker layout (hyperreal system, immersive hyperreal system, dome…)
- Frontal system resolution (number of scene speakers and extension speakers)
- Surround speaker system resolution (number of speakers and elevation layers)
- Overhead speaker system resolution (number of speakers and distribution)
- Scene system pan range
- Surround system pan range, and
- Elevation pan range
These parameters are critical to correctly configure the pre-production setup and facilitate a smooth transition to the venue where the full-scale loudspeaker design will be deployed.
‡‡        Pre-Production Setup Guidelines for Auditoria
When scaling down the system for the pre-prod auditorium, the same number of frontal (scene and extension) speakers must be used to proportionally scale down the step (distances) between the speakers according to their coordinates in the Soundvision design (see Fig. 2).
Surround speaker resolution can be reduced in the pre-prod auditorium. With the advantages of object-based mixing, we can use a lesser number of surround speakers while still being able to localize objects in a desired “direction/location.” When transitioning to the venue we benefit from a higher speaker resolution. The mix is automatically mapped to the higher number of surround speakers, which results in a more precise localization.
In the pre-prod auditorium, it is important to replicate a mixing position reflecting the same pan angle range as perceived from the mixing position in the venue, especially for the frontal system. Maximum pan angles for surround speakers should be maintained in the pre-prod auditorium, especially when deciding to reduce the number of surround speakers in order to scale down the system.
Adding propagation delays to the pre-prod speakers in the auditorium (calculated based on the distances to the mixing position in the venue) ensures temporal integrity of the mix when played in a larger space.
When tuning the speaker system of the auditorium, we must anticipate and adapt to the contour of the P.A. system in the venue. Environmental effects on sound propagation over distance must be considered during the tuning process, especially the expected HF attenuation at the mixing position in the venue (easily achieved using subtle HF attenuation of pre-prod speakers in the auditorium using a shelving filter). Simulate LF build-up indoors, which causes masking effects and leads to correction in the EQ settings of the mix.
Reverberation influences of an acoustically tricky venue can compromise intelligibility. To cater for these influences in the mix, the built-in L-ISA room engine allows users to simulate the effect in the auditorium by using the extensive setting options provided to tailor the ambience.
A highly recommended and valuable approach is to prepare a few sessions in the pre-prod auditorium, which replicate different audience listening positions in the venue. For instance, at the far rear audience areas, which are close to surround speakers. This is achieved by adjusting speaker gains and adding propagation delays, calculated according to the chosen location in the venue, to assess the integrity of the mix at various audience listening positions. The described method avoids making destructive mixing decisions that “ruin” the experience at these audience locations.
‡‡        More to Come
Stay tuned, next month we will focus on more leading immersive sound manufacturers.
David K. Kennedy operates David Kennedy Associates, consulting on the design of architectural acoustics and live-sound systems, along with contract applications engineering and market research for loudspeaker manufacturers. He has designed hundreds of auditorium sound systems. Visit his website for an extended list of immersive products and manufacturers: www.immersive-pa.com/brands.
