Fixing analog audio on the $2.58 HDMI-to-VGA adapter

(nyanpasu64.gitlab.io)

12 points | by zdw 2 days ago ago

8 comments

  • olelele a day ago ago

    What kind of mixer do you use?

    If it has balanced xlr inputs a DI will completely eliminate the earth hum. That the signal is dropped to mic level doesn’t matter much as the impedance is correct, the connection balanced and the mixer preamp designed for the purpose. // I am somewhat professional sound tech :)

    • nyanpasu64 a day ago ago

      3.5mm, I now know why conventional consumer audio devices don't use mixers, they're a ground loop party

      It's also that I don't know how to build a differential input not limited to power supply range, I do think they are sold and I have a mixer at home but it's somewhat bulky for my computer desks.

  • andrewstuart a day ago ago

    These chips appear to be 8051s with multi hundred MHz DACs.

    Be fun to program them but I can’t find any programmable devboards with the Capstone CS5213.

  • andrewstuart a day ago ago

    >> A photo revealed the chip was a NX3303X; I could not find any datasheets

    Not much information out there but these are similar chips, possibly it’s a clone?

    Capstone CS5213 datasheet:

    https://file.elecfans.com/web2/M00/2B/BD/pYYBAGHVUbyARd_-AAU...

    And also the AlgolTek AG6200 / AG6201 Series, datasheet:

    https://assets.yoreparo.com/attachments/28SGHqLW2Z2MfSzEBJB4...

    • nyanpasu64 a day ago ago

      The CS5213 appears pinout-compatible with the MX929x, interesting. The AG620x is a chip I've had the misfortune of encountering; it was common in Amazon DACs, dropped signal output every 15 minutes or so unless you disconnected the EDID pins from the (monitor?), and interprets input signal in a cursed fashion where 16 or below produces black but only 255 produces full white. If your computer outputs limited range HDMI the analog signal can't reach white, but if your computer outputs full range HDMI the shadows are clipped. This is one of the chips that gave HDMI DACs a reputation for black crush and caused CRT communities to recommend DP.

      Interestingly the MiSTer game system community actually patched their FPGAs to output digital signals from 16-255, and have some other way of avoiding the signal dropouts (never talk to EDID?), so this chipset is almost seeked out over incompatible models.

      • andrewstuart a day ago ago

        Gemini suggested to me that a number of these chips are “industry standard drop in replacements” for each other effectively clones.

        But finding more information to settle it would take googling in a desktop for a few hours chasing down weird Chinese forum rabbit holes.