TL;DR: A friend and I are developing a DSP amp and are seeking feedback on our proof of concept.
Note to admins: This post is not intended for commercial purposes. I have deliberately avoided advertising any brand or product names. The sole purpose is to gather feedback for our feasibility study on a project that may potentially become commercial in the future.
Dear fellow engineers and enthusiasts,
This is a prototype of our audio amplifier, which is based on the ADAU1452 DSP and two TAS3251 chips in the output stage. This setup provides a total output of 4x175W (or 2x350W) at 36VDC.
After several months of development, we now face some critical decisions, the most important being the viability of this device for mass production and the potential features to add or remove since this proof of concept.
This version is not the final iteration; we are still optimizing certain parameters. Most notably, the THD+N currently measures at 0.08% at 100W into 4Ohm and 0.008% at 10W into 4Ohm, with an A-weighted noise floor around 105uV. While these numbers are quite good, they do not fully match the TAS3251 datasheet. We are continuing to optimize the PCB layout, LC filter components, and PFFB.
We aim to provide plug-and-play functionality for this device, meaning users will not need to tweak the ADAU DSP and can select one of the pre-made use cases that are easily configurable and controlled via a user interface. For more advanced users, full access to the ADAU DSP will be available using SigmaStudio.
The main firmware, based on FreeRTOS, runs on an STM32F4 MCU. This MCU initializes and controls the DSP and amp chips, among other functionalities on the board. The audio signal path is also managed through the MCU, allowing for various measurements such as level metering and FFT. Additionally, the MCU handles USB audio input and the user interface.
We are also considering integrating 3rd party module to significantly enhance connectivity and streaming capabilities.
Our current focus is to prepare the hardware fully, so all new features can be added or enabled simply by updating the firmware in the future.
Please share your thoughts on how appealing this project is to you and what features you would like to see added or removed. Your feedback will be invaluable in guiding our next decisions. Below is a detailed list of features.
Thank you!
Notable features:
Inputs:
User interface:
Powering:
Connectivity:
Upgradability:
Note to admins: This post is not intended for commercial purposes. I have deliberately avoided advertising any brand or product names. The sole purpose is to gather feedback for our feasibility study on a project that may potentially become commercial in the future.
Dear fellow engineers and enthusiasts,
This is a prototype of our audio amplifier, which is based on the ADAU1452 DSP and two TAS3251 chips in the output stage. This setup provides a total output of 4x175W (or 2x350W) at 36VDC.
After several months of development, we now face some critical decisions, the most important being the viability of this device for mass production and the potential features to add or remove since this proof of concept.
This version is not the final iteration; we are still optimizing certain parameters. Most notably, the THD+N currently measures at 0.08% at 100W into 4Ohm and 0.008% at 10W into 4Ohm, with an A-weighted noise floor around 105uV. While these numbers are quite good, they do not fully match the TAS3251 datasheet. We are continuing to optimize the PCB layout, LC filter components, and PFFB.
We aim to provide plug-and-play functionality for this device, meaning users will not need to tweak the ADAU DSP and can select one of the pre-made use cases that are easily configurable and controlled via a user interface. For more advanced users, full access to the ADAU DSP will be available using SigmaStudio.
The main firmware, based on FreeRTOS, runs on an STM32F4 MCU. This MCU initializes and controls the DSP and amp chips, among other functionalities on the board. The audio signal path is also managed through the MCU, allowing for various measurements such as level metering and FFT. Additionally, the MCU handles USB audio input and the user interface.
We are also considering integrating 3rd party module to significantly enhance connectivity and streaming capabilities.
Our current focus is to prepare the hardware fully, so all new features can be added or enabled simply by updating the firmware in the future.
Please share your thoughts on how appealing this project is to you and what features you would like to see added or removed. Your feedback will be invaluable in guiding our next decisions. Below is a detailed list of features.
Thank you!
Notable features:
Inputs:
- I2S
- SPDIF
- Bluetooth with aptX
- USB audio class
User interface:
- GPIO and Rotary encoders
- All features controllable over I2C registers and through SCPI interface on UART
- Few RGB LEDs on board
Powering:
- 36VDC up to max power
- USB-PD up to 100W (up to 240W in the future once the technology becomes available)
Connectivity:
- Point-to-point stereo link with another module using CC8520
- Integration with third-party module for streaming services such as Spotify, Apple Music, Amazon Music, Tidal, Deezer, Qobuz, TuneIn, and more...
Upgradability:
- Main firmware upgradable over USB
- USBi interface emulated by main firmware, allowing real-time DSP tuning and debugging without a dedicated hardware programmer
Attachments
Hi. Really excited about this project.
It would be good if you can get the THD+N to <0.03% at 100W.
How are you managing the connection between ADAU DSP and SigmaStudio.
I'll take a few of the first batch for sure.
Chris
It would be good if you can get the THD+N to <0.03% at 100W.
How are you managing the connection between ADAU DSP and SigmaStudio.
I'll take a few of the first batch for sure.
Chris
Hi Chris,
we would like to get close to datasheet values, meaning THD+N <0.01% at 100W. With proper utilization of PFFB, it could be even less, but I can't promise that. There is still lot of work to do.
Regarding the ADAU DSP and SigmaStudio connection, for the prototype and perhaps for the first batches, there will be the standard programming connector compatible with USBi adaptor. However, the ADAU I2C is also routed to STM32 and later we would like to emulate the USBi interface completely in the STM32, so the onboard USB could be used without the need for external USBi programmer. On all released boards, this will be enabled by FW update.
Thank you very much for your interest. We aim to launch first batch at the end of this year.
Jan
we would like to get close to datasheet values, meaning THD+N <0.01% at 100W. With proper utilization of PFFB, it could be even less, but I can't promise that. There is still lot of work to do.
Regarding the ADAU DSP and SigmaStudio connection, for the prototype and perhaps for the first batches, there will be the standard programming connector compatible with USBi adaptor. However, the ADAU I2C is also routed to STM32 and later we would like to emulate the USBi interface completely in the STM32, so the onboard USB could be used without the need for external USBi programmer. On all released boards, this will be enabled by FW update.
Thank you very much for your interest. We aim to launch first batch at the end of this year.
Jan
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This looks very interesting, I will be keeping track of what happens here. Thanks for the work, hopefully the end result is to your liking.
