I came across a project in Sigma Studio in which they simulate the operation of a tube amplifier. What attracted me to this project was the ability to control the level of distortion. I made a distortion adjustment using an external potentiometer from 0.005% to 15%.
The result was quite interesting. This project is a good way to test your threshold for sensitivity to distortion.
The design of the project introduces distortions according to this principle:
-When changing frequency, the level of distortion is almost the same for any frequency;
-As the signal level decreases, distortion increases;
-Even harmonics prevail over odd ones.
Project in Sigma Studio.
The result was quite interesting. This project is a good way to test your threshold for sensitivity to distortion.
The design of the project introduces distortions according to this principle:
-When changing frequency, the level of distortion is almost the same for any frequency;
-As the signal level decreases, distortion increases;
-Even harmonics prevail over odd ones.
Project in Sigma Studio.
For those who are interested in the optical input, I posted boards with an optical input on eBay.
Optical input/output
Optical input/output
For some time now I've been working with an ADAU1701 DSP board and separate 2x50w and 1x 100w amplifiers trying to get things to work well together to manage a three way active speaker project. Problems with numerous power supplies, ground loops and general incompatibilities. I was about to re-ignite long lost electronics knowledge and design my own when I saw this post.
I purchased one of the boards and have been working with it for a few weeks now. The unit was delivered on time, well packed, Uriy-ch was in touch throughout, followed up on delivery and has been very helpful with information advice and resolving a few queries on my side.
The amp has been very easy to work with. I'm powering it from a 20V DC power pack to start with as recommended. I reviewed the amp listening on a known set of speakers and was very pleased with the lack of any high frequency hiss which is present on most of the other amplifier boards I have. It has more the enough power for my needs and sound quality is excellent.
Programming has been straightforward, I'm using a Dayton Audio in circuit programmer but any SPI programmer should work fine. The three Sigmastudio projects provided are great starting points. I have settled on the 3 way design but with manual EQ rather than the AutoEQ algorithm which I haven't mastered yet.
I can thoroughly recommend this for integration into DIY speaker projects or as a standalone 2.0 or 2.1 amplifier
I purchased one of the boards and have been working with it for a few weeks now. The unit was delivered on time, well packed, Uriy-ch was in touch throughout, followed up on delivery and has been very helpful with information advice and resolving a few queries on my side.
The amp has been very easy to work with. I'm powering it from a 20V DC power pack to start with as recommended. I reviewed the amp listening on a known set of speakers and was very pleased with the lack of any high frequency hiss which is present on most of the other amplifier boards I have. It has more the enough power for my needs and sound quality is excellent.
Programming has been straightforward, I'm using a Dayton Audio in circuit programmer but any SPI programmer should work fine. The three Sigmastudio projects provided are great starting points. I have settled on the 3 way design but with manual EQ rather than the AutoEQ algorithm which I haven't mastered yet.
I can thoroughly recommend this for integration into DIY speaker projects or as a standalone 2.0 or 2.1 amplifier
For those who don’t like FIR crossover but want to have an even phase, I put together a subtractive crossover in Sigma Studio.
The frequency response and crossover circuit turned out like this.
And this is the measured step response of the sum of three bands.
Below is a project in Sigma Studio.
The frequency response and crossover circuit turned out like this.
And this is the measured step response of the sum of three bands.
Below is a project in Sigma Studio.
Do you plan to build 4 channel version, 2x100W plus 2x30W for 2 way active speakers ? I'm looking for something like that. It could be also perfect caraudio DSP amplifier.
I do not plan. There is no space on the board and the microcircuit does not have enough pins.
There are many industrial solutions for cars.
If you use two three-way boards, then you can use the third channel of each board as an output for a subwoofer that can be placed under the table, which will greatly simplify the task of choosing a speaker for a compact active two-way speaker.
Having dug a little into the settings of the adau1452, I realized that the way I had previously used to increase the frequency on the I2S output of the adau1452 is not the optimal way.
It is more optimal to use frequency increase using ASRC; this way eliminates the need to filter the output signal and is generally more rational.
To increase the frequency, I used ASRC2, ASRC3, since ASRC0 and ASRC1 are busy processing the input data stream.
The use of ASRC made it possible to simplify the output part of the project, and the use of ASRC made it possible to use SPDIF transmission from the DSP core at project frequencies of 48 kHz or 96 kHz, which previously could not be done. Also now the board goes into sleep mode more stably when there is no data flow at the input.
Below I have posted basic projects in Sigma Studio configured for different sampling rates within the project using ASRC to increase the frequency on the I2S output.
It should be taken into account that the pin numbering has now changed. Now outputs 4=Ch0, 5=Ch1, 6=Ch16.
It is more optimal to use frequency increase using ASRC; this way eliminates the need to filter the output signal and is generally more rational.
To increase the frequency, I used ASRC2, ASRC3, since ASRC0 and ASRC1 are busy processing the input data stream.
The use of ASRC made it possible to simplify the output part of the project, and the use of ASRC made it possible to use SPDIF transmission from the DSP core at project frequencies of 48 kHz or 96 kHz, which previously could not be done. Also now the board goes into sleep mode more stably when there is no data flow at the input.
Below I have posted basic projects in Sigma Studio configured for different sampling rates within the project using ASRC to increase the frequency on the I2S output.
It should be taken into account that the pin numbering has now changed. Now outputs 4=Ch0, 5=Ch1, 6=Ch16.
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To be honest, setting the project frequency in Sigma Studio is a very non-obvious thing; I had to go through the options for a long time to understand how to correctly specify the settings that will satisfy the project frequency.
Also, those wishing to use the 5V power bus for external devices should take into account that the current that this pole can produce does not exceed 100 mA, it is best to take no more than 50 mA from it.
Also, those wishing to use the 5V power bus for external devices should take into account that the current that this pole can produce does not exceed 100 mA, it is best to take no more than 50 mA from it.
Hi - I'm finding the heatsink is getting quite hot. It's drawing 300mA from the power supply (27V) but the heatsink is almost too hot to touch - this is with no music playing. Is this what you'd expect? Room temp is around 20DegC.
All. The boards are gone.
The next boards will have a slightly larger number of additional service ports, I also tested connecting the ESP32 to the board via I2S and broadcasting audio over WiFi, I really liked the result of stable streaming that supports 24 bits via I2S, and for this reason I will make input boards with an optical input and output and ESP32. When I assemble new boards, I will show the results and write more about the new features of the input board.
The next boards will have a slightly larger number of additional service ports, I also tested connecting the ESP32 to the board via I2S and broadcasting audio over WiFi, I really liked the result of stable streaming that supports 24 bits via I2S, and for this reason I will make input boards with an optical input and output and ESP32. When I assemble new boards, I will show the results and write more about the new features of the input board.
I collected the next revision of the boards and opened a new thread to avoid confusion.
https://www.diyaudio.com/community/threads/3-way-dsp-amp.415065/#post-7734899с
https://www.diyaudio.com/community/threads/3-way-dsp-amp.415065/#post-7734899с
I'm curious what compromise you came to as a solution to this. Is it the "subtractive crossover" with flat phase you mentioned further down the page? Also these boards look great and I would be curious to pick some up when your new version has more in stock. Cheers!I found measurement results in my archives when I was playing with setting up three-way speakers on FIR filters.
Below in the picture, the red frequency response is before correction, the black frequency response is after correction, and the most interesting thing further is the step response of this whole undertaking.
I’ll say right away that listening to speakers with such an frequency response is very problematic because the entire sound is exposed, the slightest flaws in the mixing of the music can be heard, later I took a different approach, it allowed me to find some kind of compromise between musicality and sound detail.
On the frequency response I showed earlier, 1/24 octave smoothing was applied, i.e. when correcting the frequency response, I used a very high resolution, which led me to a very analytical sound. Later, I made a correction with different octave smoothing 1/3, 1/6, 1/12 1/24 and psychoacoustic octave smoothing and after listening to each option, I chose the option that was optimal to my ear between the detail of the sound and its musicality. In my conditions, I liked the frequency response correction with psychoacoustic smoothing the most. I think it is worth adding that I get the reference frequency response in the listening area, i.e. I make the frequency response correction taking into account the reflections in the room, so I partially compensate for the influence of the room on the sound. With all this, I do not automatically build the correcting frequency response at frequencies below 300 Hz, below 300 Hz I use manual frequency response correction.
FIR filters for 512 taps in the crossover were enough for me to get a flat phase and optimal frequency section steepness. I did not check the subtractive filter by ear, since I wanted to have steep frequency sections to reduce the joint frequency zone of the speakers, this greatly facilitates the receipt of small distortions from the speakers.
In general, you can configure your speaker system in different ways, and this depends on the preferences and conditions of use of this speaker system, there is no single and universal method for setting up a speaker system, I believe that everyone should find the method that will allow him to get the sound that he is looking for in his conditions. My way is not universal, it has both advantages and disadvantages. But it was in my conditions that it gave me a result after which I do not want to reconfigure the speaker system.
Keep an eye on this thread, I'll be posting how many boards are available soon.
https://www.diyaudio.com/community/threads/board-3-way-dsp-amp.415079/page-2
Very interesting, thank you for the explanation! I had heard before that FIR type correction could lead to hyper revealing or overly analytical sound and was curious for possible remedies while keeping phase intact. Gives me some fun things to try.
Excellent, thanks!!