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-   -   Cheap DSP to learn about active multi-way speaker (https://www.diyaudio.com/forums/multi-way/369868-cheap-dsp-learn-active-multi-speaker.html)

Neil Davis 25th March 2021 01:43 AM

You can have one of these boards for free by simply buying the owner a coffee. They are an early design that is no longer supported, but they work and are a good way to learn about the ADAU1701 and how to control it. You can have the code, but it is very difficult to follow--see the main blog (Feb 16, 2021) for details.

robca 25th March 2021 04:46 PM

Quote:

Originally Posted by benjaminandrews38 (https://www.diyaudio.com/forums/multi-way/369868-cheap-dsp-learn-active-multi-speaker-post6586181.html#post6586181)
I'd recommend downloading and playing with sigma studio before settling on a specific dsp chip. you can throw a few filters together quite quickly, and see whether or not your program will fit on a 1701. Furthermore, the more ubiquitous 1452 options on Aliexpress have the dsp chip on a seperate board to the codec, that way if you wanted to roll your own adc/dac board it could give you a jumpstart.

I didn't realize that the 1452 boards had the option to use a separate codec board with AD1938, which definitely adds a lot of flexibility. Thanks for pointing that out.

Yes, I downloaded Sigmastudio and promptly got lost :) :) Lots and lots of functionality, even for the "lowly" 1701. I will probably get the cheapest 1701 board and use a signal generator+oscilloscope to see what happens to the signal with the various options. Right now, given my lack of DSP experience, most of those options are obscure.

robca 25th March 2021 04:57 PM

Quote:

Originally Posted by Neil Davis (https://www.diyaudio.com/forums/multi-way/369868-cheap-dsp-learn-active-multi-speaker-post6586199.html#post6586199)
You can have one of these boards for free by simply buying the owner a coffee. They are an early design that is no longer supported, but they work and are a good way to learn about the ADAU1701 and how to control it. You can have the code, but it is very difficult to follow--see the main blog (Feb 16, 2021) for details.

Thanks Neil, really appreciated. Will follow up with you in a PM for this.

Incidentally, and I'm sure you hear it a lot, I'm a big fan of your site, which I discovered early in my exploration. Still slowly digesting the content, and I'm blown away by how much work you did on the site. Kudos and thanks for sharing your knowledge with us

Neil Davis 29th March 2021 10:16 PM

I found a suitable box for the learning board, and I'll send out tomorrow. You will need a microUSB cable to power it up. I'll send out the code tomorrow as well.

I wrote up some new information about the software at this link: Finally: Some Shareable Code – Audiodevelopers Reborn

That write-up might give you a better idea of how the code is organized, plus what sort of collaborative effort I would be interested in. Again, my time is limited right now, but I'm not going to walk away from many years of work on this project, either.

My primary interest right now is either line arrays or multi-way speakers with more than 3 bands of DSP (5-way, for example). So, I'm not really interested in "perfecting" the 3-way software...just trying to re-architect it so it is modular library code that I can adapt to these other designs.

jjasniew 29th March 2021 11:37 PM

@robca; "And I'd like to learn more about handling sounds purely in the digital domain (then converting to analog at the proper time)"

You could try your hand at TI TAS amplifiers, using the Zoudio board (~$100) found in the https://www.diyaudio.com/forums/vendor-s-bazaar/. It's good for running a pair of two way speakers; other configurations are possible.

TAS amplifiers do DSP "purely in the digital domain" and convert to analog at the power output stage. Unsure if that's "the proper time" for you or not. I think the sound is nice.

Setup of the amplifier and its DSP is all through register programming using an I2C interface. (You get one and a custom setup program when you buy the Zoudio amp).

TI however doesnt just give their control software panel away as an easy download, unless you're developing a product using their hardware. Unsure how tough a nut it would be to crack; making sense out of the register programming, which of course anyone with a I2C interface can do.

Have a look at the Zoudio amp and the TAS product line to see what you think,

robca 30th March 2021 12:03 AM

Thanks again Neil. I did send you a few coffees as a small token of appreciation.

In parallel, I started building a framework to program an ADAU1701 using "modern" ESP32 libraries. I'm using quite a few standard libraries (including the MCUdude one), a WiFi manager with captive portal to set the device upon first power on, then a website offering the device UI (using the modern Bootstrap reactive framework, with the ability to duplicate basically the same functionality of the Android app), including the ability to upload newer versions of the web UI over the air. Also the overall firmware can be updated over the air. Basically once the ESP32 is programmed the first time, everything that needs updating is done over the air using the web server in the ESP32 itself, requiring nothing more than a browser. And all settings are retained even between updates.

At the moment is nothing more than a rough skeleton, with none of the actual functionality. It's gong to be quite a lot of work to get it to full functionality, but the basic concepts are in place and working. I will contact you separately to see how open you are to allow me to reshare the code using your same logic (i.e. ADAU1701 generic implementation plus an Arduino device to change parameters in real time) and/or to port your code to the new framework. I will not share anything coming from you without your preliminary approval, to be clear.

Since I plan to sooner or later diverge from your functionality in my experiments, developing a more modern ESP32 implementation will help me anyway for any device I will end up building. And the basic functionality I'm implementing now will work for any future ESP32 project of mine where I need a web server implementation, so worth doing on its own.

If you are interested, I can send you a skeleton proof of concept in a few days, just to give you a sense of how it will look like.

If any of the above gives you concern even after my assurances, I would suggest holding off on sharing your code until I can address your concerns. The last thing I want to do is play fast and loose with someone else IP and hard work

robca 30th March 2021 01:04 AM

Thanks @jjasniew, I'll look into that.

But from a cursory look and based on what I learned in the last few days, the ADAU1701 seems a better option, not only because the tools are freely available, but also because most of the more powerful ADI DSPs are pretty much compatible with each other and very affordable. For example, the ADAU1462 which can also use external codecs is available for ~$40 on Aliexpress (codec boards are extra)

I also would like to limit moving from analog to digital domains too many times. My main sources are all digital (streamers or PCs), and can provide SPDIF outputs. The ADAU1701 can accept I2S signals, and with a cheap SPDIF to I2S converter I can avoid going PC->DAC->A/D to ADAU1701->DAC to the D class amplifier. Even better, with an ADAU1462, I can get PC->SPDIF directly to ADAU1462-> SSM3582 which is a D-class amplifier that can use digital inputs directly. Everything happens in the digital domain, with no analog components apart from the speakers and my ears :)

So even if I'm not ready to go ADAU1462 & SSM3582 yet, learning on the ADAU1701 will be more usable later on

DorinD 30th March 2021 09:21 AM

https://ro.mouser.com/ProductDetail/...RjMpIH0w%3D%3D

EVAL-ADAU1466 Evaluation Board | Analog Devices


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