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It somehow feels like you put a lot of thought into this already and missed starting from the beginning in this post.
What device do you want to have a USB-C DAC for? What's the actual size limitations and what power do you want to draw that would need a heatsink? Do you have specs in mind, or is there a comparable project already available to look at?
I've put some thought into it, but realistically I lack the experience to flesh out the idea.
I've seen a few small DAC concepts out there, like https://www.elektroda.com/rtvforum/topic4091483.html or that iPhone modification that Strange Parts did a few years ago, but none of these really 100% match my needs. As for the sizing, the only real answer I have for you is "small" - whilst it is intended for integration into a phone, I'm going to be building a housing for that phone from scratch, so the size requirements are somewhat led by the dac itself. I had a few ideas about using a flexi-strip in place of a solid PCB too, but I think that's aiming too high for my non-existent skillset. Instead, I have no problem redesigning the board to be long and thin if necessary, or squat and fat in the alternate. Realistically, it's probably going to be somewhat L-shaped, but there's a good two inches or more of width and something like six inches of height to work with - minus the PCB of the phone, that is.
The actual handset it will be accompanying is a Sony Xperia 1 IV, but that's largely meaningless as we can add pretty much any additional size to it up to a reasonably large handset within the last ten years (preferably with an OLED display, but I'll be somewhat limited in terms of compatibility anyway and might have to end up running the screen in an alternate fashion somehow, I haven't thought too hard about that side of things because the project is useless if I can't design a DAC inthe first place).
The heatsink stuff was really just a suggestion, I'm not actually sure if it will be necessary, but it's good to have the option.
Specifications wise, it essentially needs to do four things:
The bit that I'm stuck on, really, is the addressable EQ. I could possibly go with some sort of Arduino-esque solution, but that's a lot of lifting for a single-purpose device. I have no idea where else to start looking - I know there are RISC chips out there that run on nothing but a button cell, but again I'm clueless as to whether or not this is a good idea.
Thanks for the detailed answer, that helps a lot for my understanding.
The project sounds like a lot of work, especially for such a niche application. Do you have a crowd to support this (with time or money) or do you plan pay for this and sell it in the end?
Neither. This is a purely personal project, and I'm using as much off-the-shelf as possible. The dac itself doesn't have to be top of the line, just decent. The PCB itself I'll probably just have printed, rather than trying to breadboard it or make some ungodly wire mess.
Some stuff I can get for almost pennies, like a USB-C controller and the actual sockets and plugs, so this is a non-concern. The actual dac chip though, I'm expecting (or at least hoping) to find something around the £30-£40 mark, although this may well be aspirational. That said, this is something I can theoretically transplant to my next device, and the next after that, assuming I create custom housings for them.
I'm in no position to discourage you from building this, but this is a fsr greater project than you're writing it to be. Send me a link to the git repo, so I can tag along and keep updated!
Hmm. Git is far too organised for my play style. I may take photographs at some point, assuming I can actually find components (and learn how to do... well, any of this).
The USBC to 1/8 adapters for phones, particularly the iPhone have an integrated DAC.
I've looked at these, but they lack the integrated amplifier (afaik) and the configurable equaliser. Those are two super important features that pretty much break the idea for me.
First thing I thought of too.
Sorry OP, you’re not building anything smaller than this cheap item from apple.
Using these as a starting point and modifying as needed is probably a good thing to look at before you go too far down the rabbit hole.
After a night's thought, this might be an interesting idea. Although I'd need to figure out how to add a programmable interface to it.