Propagation delays do not matter if DAC and ADC are asynchronous and isolator channel-to-channel skew is low.
That ADC is really cool! I'd buy one. I was looking ad one of those AD Eval boards because I didn't want to spend the $1800 for the Mytek unit. Is it balanced and single ended input? I'd buy one if you're open
IIUC the USB isochronous limits each direction to 1024 bytes pres microframe which unfortunately allows only 1 channel at 1.5MHz 24/32 bits. Unless multiple transactions/high-bandwidth mode is used which is a major complication for the USB device (but stock windows&linux UAC2 host drivers should support out of the box).
Hello,
That's sound great !
My actual hardware i already capable to provide up to 24bits/1536kHz I2S stream with 98.304MHz clock (OSVA project posted here).
So I think I will build one of your board to test it, or maybe you would have one already assembled available for sale ?
Regards.
Frex
Thanks for the compliment. And the first post that is on topic. Input is either differential or single-ended. I've sent you PM.
Depends on how syncing is done. If I2S output is synced to I2S input (BCK & LRCK), then 2 isolators are involved. But if just MCK is shared between ADC and DAC only 1 isolator per direction is involved so propagation delay has no influence if channel-to-channel skew is low.
@TNT made very interesting recordings with Cosmos ADC and my AK5394A ADC version presented in this thread.
https://www.diyaudio.com/community/threads/fixed-gain-field-recorder.373352/post-7862343
Both recordings sound fine but surprisingly different especially with headphones. Listen for yourself and post your opinion on TNTs thread.
https://www.diyaudio.com/community/threads/fixed-gain-field-recorder.373352/post-7862343
Both recordings sound fine but surprisingly different especially with headphones. Listen for yourself and post your opinion on TNTs thread.
@bohrok2610
Do you have a preference when it comes to your resistor and capacitor selection? Or are you more in the camp if it measures well it will sound well?
Do you have a preference when it comes to your resistor and capacitor selection? Or are you more in the camp if it measures well it will sound well?
I only use brand-name components from Mouser/Digikey but not "audiophile" components. For analog stages I use primarily Vishay-Beyschlag MELF 0204 resistors and C0G capacitors whenever possible (Murata, Taiyo Yuden, TDK, Samsung). BOMs in my first posts in this thread list the actual components used.
Here is a new version of the STM32F723 I2S-USB board firmware.
I added some features that could be interesting to other STM32 projects as well:
Set feature can be used for higher level functionalities:
I added some features that could be interesting to other STM32 projects as well:
- USB HS DFU bootloader (DFU = Device Firmware Upgrade). This can be used e.g. to upload a new firmware using the USB port.
- USB Custom HID interface. This can be used to change the configuration remotely via USB at runtime. E.g. with SimpleHIDWrite or by implementing a dedicated Windows GUI. Of the 2 ADCs in this thread only ES9822PRO has configuration settings.
- Configuration data backup in flash memory
- Set register
- Set feature
Set feature can be used for higher level functionalities:
- Clip detection on/off
- Clip detection level
- Mono/stereo mode
- Filter setting
- Save configuration
- Reset
- Switch to DFU
Listening tests revealed that my AK5394 ADC had inverted left channel due to layout mistake 😳
Here are corrected schematic and gerbers.
Here are corrected schematic and gerbers.