The Polyphonic Frugal Wave Field Synthesis (WFS) system is an FPGA-driven spatial audio platform designed to make real-time WFS accessible and reproducible. The system installed at CCRMA serves as an interface connected to the existing speaker array.
This page provides a complete walkthrough of the system architecture, hardware, software, and usage instructions.
This system allows you to place virtual sound sources in space, both behind and in front of the bar, using Wave Field Synthesis (WFS), a spatial audio technique that reconstructs the sound field of virtual sources by reproducing their wavefronts through a loudspeaker array.
As currently configured, the board drives only the bottom array of 32 loudspeakers. Additional boards can be connected to enable the full speaker range or to integrate further arrays. For more information, please contact me.
The system is composed of two boards. The smaller board, which contains the FPGA, will be referred to as the FPGA board. The larger board, which contains the amplifiers, will be referred to as the amp board. Connect the two boards as the picture below.
For simplicity, the amp board uses Sub-D25 connectors. Using the provided custom cables, connect the DB25 ports to the speaker array. The DB25 connectors are numbered 1 to 4. On the speaker array side, connect each cable to the correspondingly numbered port. Be careful, these connectors are fragile!
Connect the power supply to the FPGA board. Use a 5 V power supply (center-positive) capable of delivering at least 4 A for a single 32-channel unit. Then connect an Ethernet cable to the FPGA board.
The FPGA board outputs two identical power cables at the top. Connect one of them to the amplifier input power connector located on the right side of the amp board.
The FPGA boots automatically when powered on. Boot is complete when the Polyphonic logo turns green. You can then begin communicating with the system via Ethernet.
To create the server, clone our Git repository:
https://github.com/inria-emeraude/syfala
Navigate to the server directory:
cd syfala/source/linux/syfala-server
Then run the server using Rust (install Rust if needed):
pw-jack cargo run --release
If the server is running correctly, you should see a message similar to:
INFO server/src/main.rs:114: Starting UDP
You should now see the system in your preferred JACK routing tool. For example, you can use qpwgraph.
You can now connect your audio sources from your DAW to the system (see the Ardour example in the image below).
You can either use the interface written in Processing (install Processing if needed).
Open the following file with the Processing GUI and run it:
syfala/examples/cpp/wfs/interface/hls_wfs/hls_wfs.pde
You can also send OSC commands directly, controlling the x and y position of each source with the following convention:
"/wfs/source<i>/y/<yPos>"
"/wfs/source<i>/x/<xPos>"
Replace <i> with the source number.
yPos is typically in the range -4 (source far away) to 4 (source near), and
xPos is typically in the range -2.5 (left) to 2.5 (right).
Great… let's start by checking the LEDs on the side of the board.
Use the following checks to diagnose common issues:
On the host machine, verify the following:
pw-jack cargo run --release?
If the problem persists, please contact:
maxime.popoff@inria.fr