Linux🐧Audio🎧Conference🎙️2019🔈BRINGING THE GRAIL CCRMA🔊diffusion🔉system🐉MasteringSurpriseByNTVMAEBUS

Bringing the GRAIL to the CCRMA Stage | Design process of a complex Linux-based diffusion system, using off-the-shelf components and GNU/Linux
for all the software components.

Mute all songs | Copyright Owner’s policy
1:25 Introduction By Fats Gonder / Opening | James Brown 1:48
6:07 Follow the Rules Song | Heidi Butkus 6:20
17:15 Signal To Noise | Peter Gabriel 17:26

Proceedings of the 17 th Linux Audio Conference (LAC-19), CCRMA, Stanford University, USA, March 23–26, 2019

Linux Audio Conference 2019 March 23-26, 2019 — CCRMA, Stanford University (USA)
“In Ping(uins) we trust”
After seven years outside of the United States, Linux Audio Conference (LAC) took place at Stanford University on March 23-26, 2019 for its 17th edition! LAC LAC is …

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The Stage, a small concert hall at CCRMA, Stanford University,
was designed as a multi-purpose space when The Knoll, the building
that houses CCRMA, was renovated in 2003/5. It is used for
concerts, installations, classes and lectures, and as such it needs to
be always available and accessible. Its support for sound diffusion
evolved from an original array of 8 speakers in 2005, to 16 speakers
in a 3D configuration in 2011, with several changes in speaker
placement over the years that optimized the ability to diffuse pieces
in full 3D surround. This paper describes the evolution of the design
and a significant upgrade in 2017 that made it capable of rendering
HOA (High Order Ambisonics) of up to 5th or 6th order, without
changing the ease of operation of the existing design for classes and
lectures, and making it easy for composers and concert presenters to
work with both the HOA and legacy 16 channel systems.

We have been hosting concerts at CCRMA since it was created in the
70’s. In 2009 we started expanding our concert diffusion capabilities
while gearing up for the inaugural season of a new concert hall being
built at Stanford, the Bing Concert Hall. In 2013 we were able to
use our newly created GRAIL system (the Giant Radial Array for
Immersive Listening) to diffuse concerts with out own “portable”
speaker array with up to 24 speakers and 8 subwoofers arranged in a
dome configuration for full 3D surround sound diffusion .

1.1. From WFS tests to HOA in the Stage





5.1. Firmware giveth…

5.2. Digital Mixer Mode

5.3. Routing the Subwoofers

5.4. And firmware taketh away…

5.5. OpenMixer Mode

5.6. Switching modes

5.7. What? More Speakers?

5.8. Control Software

5.9. Calibration


6.1. Motu vs. Jack vs. PulseAudio

The opening concerts of the newly upgraded Stage took place in October
4/5 2017, and the system performed very well (at the time we
were still using the old subwoofers). Another round of upgrades in
2018 replaced the original subwoofers with newer ones, as outlined
above, and also upgraded the main 8 speakers with newer A77X
Adam monitors. The lower layer of speakers were repositioned at
the bottom of the main towers, and the new subwoofers were stacked
immediately above them (originally they had been reversed). A second
round of successful concerts (our annual Transitions concerts)
took place in October 2018 with the fully upgraded array. The full
array has seen more use in the past year, with several concerts using
it instead of what would have been stereo or quad diffusion.
We have outlined the design process of a complex Linux-based
diffusion system, using off-the-shelf components and GNU/Linux
for all the software components.


“Openscad, the programmers solid 3d cad modeller,” http:

Paul Davis, “Jack audio connection kit,”
/, 2002.

“The avnu alliance (avb),”


“Openavnu git repository,”

Fons Adriaensen, “Jconvolver, a convolution engine,” http:

Denis Sbragion, “Drc: Digital room correction,”
, 2002.

Fons Adriaensen, “Aliki, an integrated system for impulse
response measurements,”
, 2006.

Ingo Molnar and Thomas Gleixner, “Real-time linux, the preempt_
rt patches,”
, 2000.


linux foundation



I am an avid Linux lover and open source enthusiast. I use Ubuntu and believe in sharing knowledge. Apart from Linux, I love classic detective mysteries.

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