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Thread: Audio Board Equivalent for Custom PCB

  1. #1
    Senior Member houtson's Avatar
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    Audio Board Equivalent for Custom PCB

    I've built a custom effects board with Teensy and AudioBoard which has been great fun but the connection from the Audioboard to inputs and outputs are a bit of a mess.

    I know I could tidy up the wire or add connectors but for the next version I'd like to include the functions of the AudioBoard on the custom PCB so that once complete all I need to do is plug in a Teensy.

    I'm good with the AudioBoard schematics and details and ok with basic hand soldering surface mount but the STGL5000 QFN looks tricky.

    Looking for some help or ideas:

    - anyone got experience hand soldering the QFN package successfully (don't have a reflow oven and this will be a one off so rather not invest in lots of new stuff)

    - are there any other audio board type designs that people have experience of with Teensy for basic audio project with easier to solder packages (just need 16-bit, line in and out + phones if poss)

    thanks for any help,
    Paul

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  2. #2
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    Buy an audio board, a heat gun kit, flux and solder paste, and practice "repairing" the chip. Or you could make your own boards and buy a few chips. I think the key is learning to use the heat gun and flux. If you're going to stay with the hobby, an inexpensive heat gun will be a good investment. Go watch "Jessa" on her mac repair channel, she has dozens of videos showing how to use a heat gun. Same with Louis Rossman.

    Your kit, as it is, looks as professional as any 70's mainstream stereo on the inside. Good job.

  3. #3
    Senior Member houtson's Avatar
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    thanks @boxxofrobots, not sure inside of a 70's stereo was the look I was going for but thanks for the link to Jessa

    doesn't look like many alternative options so will have a look into heat gun etc. and give that a go with and old audioboard

    cheers Paul

  4. #4
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    By the way, you CAN solder that chip with a soldering iron and flux and solder remover tape. There are also videos showing how to do it. I'd built my own surface mount boards using cardstock and fine wire and gluing the smds down before wiring them - you can solder just about anything with enough patience and technique.

  5. #5
    Senior Member Blackaddr's Avatar
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    Quote Originally Posted by boxxofrobots View Post
    By the way, you CAN solder that chip with a soldering iron and flux and solder remover tape. There are also videos showing how to do it. I'd built my own surface mount boards using cardstock and fine wire and gluing the smds down before wiring them - you can solder just about anything with enough patience and technique.
    The Teensy Audio library supports other codecs as well. Take a look at any of the control_* files. Those are your options without having to write your own stuff.
    https://github.com/PaulStoffregen/Audio

    One of the reasons I selected the WM8731 codec was the TSOP package is very hand-solderable. The Audio library has basic support for this codec, and I have extended support for a few extra features in my BALibrary for for guitar effects here:
    https://github.com/Blackaddr/BALibrary

  6. #6
    Senior Member houtson's Avatar
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    @blackaddr thanks for that, I'll look into WM8731, I can deal with TSOP so looks promising
    Your board looks great. cheers, Paul

  7. #7
    Senior Member houtson's Avatar
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    @blackaddr I've been looking at your schematic, which has been really helpful thanks for sharing it.

    I know your board is focussed towards guitars and has significant attention to that with the preamp.

    I'm only interested in Line in - in your schematic it looks as though you connect line in direct to the codec without any additional component, does that work ok or is it that you don't really use line in on that boards?

    thanks Paul

  8. #8
    Senior Member houtson's Avatar
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    First go at a new board using the WM8731 codec as suggested by @blackaddr, easy to solder and seems to work well, bit more testing to do.

    Used pretty much the application circuit from the datasheet.

    Gains all a bit off using the standard control object in the AudioLib so plan to try the extended controls in the BALibrary.

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    Screenshot of schematic with connections to Teensy 4.0 if anyone interested.

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    cheers, Paul

  9. #9
    Senior Member Blackaddr's Avatar
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    Quote Originally Posted by houtson View Post
    @blackaddr I've been looking at your schematic, which has been really helpful thanks for sharing it.

    I know your board is focussed towards guitars and has significant attention to that with the preamp.

    I'm only interested in Line in - in your schematic it looks as though you connect line in direct to the codec without any additional component, does that work ok or is it that you don't really use line in on that boards?

    thanks Paul
    Sorry for the very late reply, I missed this message a month ago. To answer you question, if you just want line in, the schematic in the datasheet is suitable. If you want really good noise performance, you may still need to create a separate clean analog supply with an LDO to supply the CODEC.

    The preamp and input overload protection is as you said, necessary for guitars, because circuits tend to operate at 9V and require very high impedance inputs making them super sensitive to noise. A lot of work went into the PCB layout of my board to ensure high performance even for guitar inputs.

    Btw, your project is looking great! Be sure to post some more pictures or videos when it's done!

  10. #10
    Hey guys. You seem to be quite experience here. Quick Question. Can you recommend a good soldering gun. And like what is the best soldering iron with regards to (wattage) to use. Oh and solder too, what's the best solder (60/40) silver base solder, Lead free? Or should I go with the entire soldering projects for beginners like https://diystadium.com/best-solderin...for-beginners/ . I'm kinda a newbie at soldering.

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