TDA1308 headphone pre-amp from DAC

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Projectitis

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Hi all,

As part of the project I'm working on I have stereo audio generated on the DAC pins of the T_3.6.
I have this TDA1308-based pre-amp board on the way to drive headphones, or maybe laptop speakers if suitable. Here's a pic:

Stereo-TDA1308-Headphone-Amplifier-Board-Headset-Amp-Preamplifier-Board-Module-3V-6V.jpg

I have next to no experience with the electronics side of things, so naturally I have a few questions :)

My setup currently is T_3.6 in a breadboard powered by USB. Currently no other hardware/buttons/anything attached.
Eventually it will be powered by a 3.6v lithium (PSP battery) and will have all sorts of other hardware also (display, analog and digital inputs, serial wifi board etc).

  1. Can I connect my L/R audio directly from DAC to the inputs on this board, or do I need a capacitor also, as I've seen in another thread where DAC pins are connected to powered speakers?
  2. Similarly, can I hook up the headphone jack directly to the outputs of this board?
  3. Do I connect the input GND pin on the board to AGND on the teensy? Or just to normal GND (i.e. v-)?
  4. Related to questions about GND, this may be too big a question for this thread alone (I have a feeling it's the result of a couple of years' tertiary study) - how can I design my eventual setup for the least interference/noise?

Any help appreciated :)

Cheers,
Peter

Edit: I've hit 2^6 posts. Nice :D
 
That's the problem when you buy cheapest Chinese stuff... On that Aliexpress product site, there are no schematics nor other important technical details. Thus, your first step should have been to avoid that seller and to buy from a company which provides all needed info to circuit developers...

1. As you can clearly see on the product pictures, the input signals go through the capacitors C1 and C2, thus, these are integrated on the PCB, no need to add others.
2. As you could have found out the same way by looking at the PCB and the TDA1308 data sheet, the answer is yes.
3. AGND
4. Build a first prototype while respecting already the common good practice for analog circuit design, check the result (Oscilloscope and SNR meter needed) and then optimize it step by step until it fits the desired technical specifications.

Edit re question #4: http://www.analog.com/en/analog-dialogue/articles/staying-well-grounded.html
 
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Thanks for the advice, Theremingenieur, though it clearly irked you to give it.
Some things are not as obvious to others as they are to you.

Edit: also thanks for the link. I’ve got a bunch of reading to do :) I’ve seen many threads regarding grounding in this forum, so I expect it’s a very involved topic.
 
Projectitis,

I recently purchased the audio shield for my T3.2 and using it for a microphone level monitor. The unit has a headphone jack, not sure if that helps, but getting it to work and the supplied libs make that process easy. Not sure if that unit will do what you need, but it appears to check your boxes.
 
Theremingenieur is bang on the money :) Also the audio shield is very large (it's actually tiny, but comparatively large!), and has many more features than I need.
I have an xm modplayer running on T_3.6 and just need the output level lifted high enough to drive headphones.

Just a note on reputable suppliers - purchasing from many suppliers from here in New Zealand (basically an island in the middle of no-where, remember) is price prohibitive. This is just an example - but if I were to purchase the audio board from PJRC it would cost me US$14.25 for the board, and either US14.39 for shipping, or the second option is US$95.61 for UPS! There are re-sellers here in NZ but they don't stock all products and are still very expensive. One other example is that I recently wanted some Adafruit IDC breakout helpers to allow double-pin headers to straddle the breadboard gap. There is ONE place in NZ that sells them (our version of mouser) for USD$5 for one, but the shipping on just that item is US$19! Now US$24 is much more than I'm prepared to pay for a header with bent pins!

That's why I tend to try to find alternatives on AliExpress and similar sites.
 
Seems that you live in a country where electronic components are sold and shipped at whorehouse rates... :D

I’ll never again complain when the French customs require me to pay additional 20% of sales tax when I receive orders from overseas!
 
Haha! We have an additional 15% sales tax currently on overseas orders, but only on orders of over $400. However, our government is changing that soon to be on all orders!
 
Well, progress. I don't have my preamp yet (expect it in a few weeks) but i'm getting some extremely crunchy sound out of the mod player! Now the fun part starts.
 
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