Ongoing - Homebrew IR Loader (trigger warning: SMD content)

[vigilante398]

My original plan was to post this in the IAIGF thread before its demise, but I figure I'll make a build report thread to keep it documented as I go. I started working on a tube-driven (naturally) IR loader pedal last year and was working with the AMT Pangaea module, which is super easy to use and I was able to design a board that it could drop into. So 7-8 months later I had something that I was ready to look at building a bunch of to sell, so I contacted AMT for a quote for more modules, and the price had nearly doubled since the first one I bought! So I said to myself


And that's what I did. Looking at their module I saw that they use the Analog Devices ADAU1701 DSP IC, and looking around I found a couple other commercially available IR loaders that also used it (like Shift-Line Cabzone), and from looking at the datasheet it seemed like the kind of thing I could figure out. So I threw together a design based on Analog's development board, and the boards showed up yesterday:



It's missing a few SMD parts as JLC was out of stock, and it needs a pot and a few switches, but I'll get it together soon. I'm still waiting on the programming tool, Analog charges $200 for theirs, so I ordered a $45 Chinese knockoff that isn't here yet. So this isn't a completed build, but I first off wanted to share my excitement because new PCBs are neat, and second off knew that if I tell someone that I'm working on something I'm more likely to actually work on it

 

[Paradox916]

That’s pretty cool can’t wait to see how it turns out.. just curious on how easy/ or complicated it will be to change IRs. will it be an app based “drag and drop” scenario or something a little more in-depth.

 

[vigilante398]

That’s pretty cool can’t wait to see how it turns out.. just curious on how easy/ or complicated it will be to change IRs. will it be an app based “drag and drop” scenario or something a little more in-depth.

So the way AMT did it is with a processor that talks to the ADAU1701, you can plug USB in and it acts like a flash drive, just drag and drop. The ADAU1701 by itself doesn't have any functionality like that, you need to convert the impulse response into a text file, run it through Analog's software, and then upload it with their proprietary USB tool.

So my eventual goal will be to get something like AMT have, a device in between the USB port and the ADAU1701 that could take a drag-and-dropped wave file and feed the IC the data it needs, but that will be down the road. This extremely early prototype will only be able to handle one impulse response at a time (though I did put an EEPROM on it so I'm going to experiment with storing and reading data with that).

 

[vigilante398]

Not real progress per se, but I added the hardware to the board last night. I still need to install the 10uF caps that the board house was out of, and I'm waiting on a digikey order for the missing regulator, then it's ready to be played with it. The programming tool I ordered from China is in the general area of my house, but it was rerouted away from our post office yesterday and is on the way back now, so hopefully I'll see it in the next couple days.

 

[vigilante398]

I hadn't updated this in a couple months as I had trouble getting it working and had shelved it, but last night I got into a mood and dug it back up as I have a moderately time-sensitive project I was hoping to get at least one IR into, so I decided I wouldn't sleep until I got an IR running on this damn thing. Fortunately it only took a couple hours for me to figure out what I was doing wrong, so I can successfully load a single IR in now.

One of the bigger struggles was that ADAU1701 erases its flash memory every time it boots, so if you cycle power it loses the program, so I have to store it in an external EEPROM, which took me an embarrassingly long time to get working. But it works, I have a Marshall 1960a loaded into it right now and it sounds excellent.

Temporary next step will be working this into a custom project for a professional bassist so I can add an IR output to his "signature" preamp pedal he's working with me on. Once I have that wrapped up I can focus on the real meat of the project which will be making it easier to load IRs. Currently I have to convert the WAV files into a list of responses with an online tool and load the list into the software to generate the patch, so I need to figure out how to move that process from the online tool to a microcontroller so I can drag-and-drop WAV files into the thing over USB and have it load them up.

Why am I telling you all this? Because if I'm working on a project and nobody knows about it, I lose motivation to work on it

 

[Harry Klippton]

I hadn't updated this in a couple months as I had trouble getting it working and had shelved it, but last night I got into a mood and dug it back up as I have a moderately time-sensitive project I was hoping to get at least one IR into, so I decided I wouldn't sleep until I got an IR running on this damn thing. Fortunately it only took a couple hours for me to figure out what I was doing wrong, so I can successfully load a single IR in now.

One of the bigger struggles was that ADAU1701 erases its flash memory every time it boots, so if you cycle power it loses the program, so I have to store it in an external EEPROM, which took me an embarrassingly long time to get working. But it works, I have a Marshall 1960a loaded into it right now and it sounds excellent.

Temporary next step will be working this into a custom project for a professional bassist so I can add an IR output to his "signature" preamp pedal he's working with me on. Once I have that wrapped up I can focus on the real meat of the project which will be making it easier to load IRs. Currently I have to convert the WAV files into a list of responses with an online tool and load the list into the software to generate the patch, so I need to figure out how to move that process from the online tool to a microcontroller so I can drag-and-drop WAV files into the thing over USB and have it load them up.

Why am I telling you all this? Because if I'm working on a project and nobody knows about it, I lose motivation to work on it

This is "cool" and I "like this"

 

[temol]

Fingers crossed. I like the project. It would be nice to have IR loader that could be build-in into ampsim or into reactive load for example.

 

[vigilante398]

So I pulled out my STM32 dev board to see if I could figure out the mass storage thing so I could plug into the computer and drag-drop IR files directly into the flash memory, and it took about 5 minutes for me to realize I don't want to do it. So I jumped on fiverr, and a very polite gentleman from India will be writing that part for me I can design circuits 'til the cows come home, but my firmware abilities are pretty much limited to Arduino. He said it should be pretty easy, so if it works out with him I'll talk to him about the next steps, which will be converting WAV files into hex files that can be sent over to the DSP.