Eleven Engineering Live Tuning
Live tuning is a technique to create and modify the digital audio processing filters on a DSP while audio is flowing through it so you can hear the effect of the filter changes live. Live‑tuning requires using Sigma Studio and connecting an Adapter Board to the DSP board. To prevent I2C conflicts with the Nadja's I2C, the DSP must be disconnected from the Nadja I2C bus and reconnected to the Adapter Board I2C. The DSP Live‑Tuning changes are volatile and the DSP will lose the tuning data when it is powered down or reset. To make the tuning persistent between power cycling Eleven Engineering will convert it to a binary format and store it in the XInC2's non‑volatile memory where it will be loaded every time the DSP is turned on.
Note: Customers are responsible for filtering out harmful frequencies for the drivers they use. Tweeters in particular can be damaged by low frequencies (<~3 kHz)
Terminology
- I2C: A communication protocol (Inter‑Integrated Circuit) that is used to program the DSP with the DSP Project File.
- I2S: A protocol (Inter-Integrated Circuit Sound)for receiving and transmitting audio on the DSP.
- Sigma Studio: Application for building and loading digital filters onto the ADAU 1701 Audio Processor.
- DSP Project File (.dspproj): File type created and used by Sigma Studio to save filter/tuning configurations.
- Digital Signal Processor (DSP): The chip that Sigma Studio programs with filter/tuning configurations. Currently all Eleven Engineering Live Tuning products use the ADAU1701 for the DSP.
- Adapter Board: Tool that is connected to the DSP and uses DSP. The Adapter Board is called "EVAL‑ADUSB2EBZ".
- Amplifier (Amp): Chip that converts I2S into audio for a driver. Eleven Engineering products typically use Merus™ for the Amp
Connections
- Diagram
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To perform live-tuning the I2C connection between Nadja and the DSP needs to be severed so the Live-Tuning I2C does not interfere with the rest of the Nadja's I2C as illustrated in the following diagram.
- Adapter Board
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The SDA, SCL, and Ground pins should be connected to the ribbon cable in the same manner as this picture.
- Saskatoon Twin
For live-tuning the Adapter Board should be connected to the DSP SDA and SCL headers as well as the Ground header.
| Mode [1] | MSEL0 | MSEL1 |
|---|---|---|
| Parallel Bridge Tied Load | LOW | LOW |
| 2 Channels Bridge Tied Load | HIGH | LOW |
| 4 Channels Single Ended Load | HIGH | HIGH |
Programming With Sigma Studio
To load firmware onto the DSP open a .dspproj file in Sigma Studio and connect the Adapter Board to the computer
- Open the .dspproj file in Sigma Studio
- Connect the Nadja I2C to the DSP and power on the board. It is important to have Nadja connected while booting up because it needs to configure the DSP to output a clock to the Amps before enabling them.
- Disconnect the Nadja I2C from the DSP and connect the Adapter Board (SCL, SDA and ground pins) to the DSP while it is powered on. Instead of jumper wires a switch can be wired onto the DSP headers to simplify this process.
- Connect the SCL, SDA, and ground pins on the Adapter Board to the motherboard.
- Plug in the Adapter Board to the computer
- Load the firmware by pressing the "Link, Compile, Download" Button in Sigma Studio. The Download Status is shown in the bottom right corner. If the DSP was programmed it should display "Download Active", otherwise it will display "Comms Failed"
- Once connected, changes to block parameters will instantly update the DSP, however adding or removing blocks and connections require the firmware to be re-downloading with the "Link, Compile, Download" Button. Additionally, since the DSP has volatile memory the DSP file must also be re‑downloaded if the DSP is powered down or reset.
- When tuning is complete, the final DSP Project File must be saved and provided to Eleven Engineering to permanently stored in the XInC2 non‑volatile memory in a special binary format. Eleven Engineering return new firmware with the final tuning.
Downloads
Saskatoon & Strawberry Twins
Standard DSP Project File for the Saskatoon & Strawberry Twins that has no EQ other than a DC blocking filter at 60Hz. This DSP Project configuration assumes Amp 1 (Top) is in BTL mode which has two separate audio outputs and Amp 2 (Bottom) is in PBTL mode which has only one audio output. Outputs can be added or removed as needed.