Get yourself a Creative Play! 4 for £20 and see what it can do.
The reason I mention the Play! 4 is I’ve used one and it has plenty of punch plus it has other features that can be handy (input) for a laptop user that other dongles don’t have.
And it’s like £20
Huh, thought USB dongles killed the thread. For the record, I did have a FiiO BTR3K when I initially wrote the post. That BT/USB adapter uses an AK4377 chip and paired with an Qualcomm chip for USB and BT duty. The parts themselves are relatively small, but the ancillary components surround the chip and effectively expand the overall required area.
Considering how dense the parts placement is on that dongle, I wouldn’t be too surprised if this imposed a jacket-catching overhang should we adapt it to card format.
I can see ways of compressing this dongle even further, such as moving the Qualcomm chip on the other side of the board and going with an even higher layer count PCB. Both the combo 3.5mm jack and balanced 2.5mm jack can remain. I’d also replace the Qualcomm chip with something smaller, like an even smaller STM32 chip since it only does USB.
Also, how tf did Apple cram a 600 ohm driver in their laptop?
I have a cheap USB audio plug that probably just has a simple CMedia audio codec chip in it (never used it, was bought for a customer that lost audio but I fixed it).
Its not much bigger then a Framework module so I guess a higher end Realtek Codec chip (ALC1220/4080?) might fit. You wouldn’t get much at the amp end though.
Oh I find those kinds of dongles pretty cheap on eBay. They’re great for wacky headset builds that need a soundcard. Of course, they’re average at best, but at that price it can’t be beat.
Still not the point of this thread though. We need to c r a m m those high-end parts into a module.
For most people, the Apple USB-C to 3.5mm headphone jack dongle should suffice to call it a day (for 32ohms earbuds and headphones).
Currently at $9 from Amazon.ca: https://www.amazon.ca/dp/B07K25P3N1
Unless you want to use them on your android phone as well…
For some reason you only get like, half volume out of those on android devices, I’m not sure about laptops. Fairly frustrating since it’s a pretty solid adapter for like, 10 bucks
I’m still working on my prototypes. Gonna be a longer process than I thought because my first attempt didn’t work - the audio codec isn’t connecting to USB, almost like it’s not getting power. I’m going to have to make larger versions to troubleshoot the circuit itself before I can get to miniaturizing it for an expansion card.
Updates:
Prototype1: USB to i2s to PCM1792 DAC to INA1620 headphone amp
Doesn’t do anything when I plug it in. Lots of likely mechanical issues because the PCB was physically too thick for the USB connector, will respin on a larger board for testing and try again. I’ll include different pads for different USB to i2s bridges - the CP2106 I’m trying to use now, a PCM2706, and a PIC32MX150 or like.
Prototype 2: USB to PCM2706, analog path to TPA6120 amp → Almost works, stymied because it turns out programming an EEPROM with USB descriptors is only optional in MOST power modes, not the power mode I’m using. A socket so I can program the EEPROM is in the mail. The original problem was silly: I forgot to hook up the power.
I’ve heard nothing from the sales support for ESS and their highly integrated chips, which is a shame. And I can’t keep throwing money at these without a success, so I can’t buy a FiiO KA1 and reverse engineer it right now.
