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MAX9744 inputs
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MAX9744 inputs

by crossoft on Thu Aug 08, 2019 3:55 pm

I'd like to connect a MAX9744 https://www.adafruit.com/product/1752 to my Raspberry Pi to get sufficient 20W output for the XS-GTF1027 https://www.adafruit.com/product/1732.

I already have the 3W bonnet and the XS-GTF1027, and can send audio output to it, using aplay, but of course it's quiet, because, 3W output, 20W speaker.

My question is, if I connected the MAX9744 to the Pi, are its inputs analog? (so that I could connect to the outputs of the bonnet)
Or, if I needed to connect it directly to the Pi for audio signal, is that I2C? Would aplay see that as an audio output selection?

I'm just trying to avoid buying a few amplifier boards only to find that they won't work for me.

Thank you!

crossoft
 
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Re: MAX9744 inputs

by adafruit_support_carter on Thu Aug 08, 2019 6:57 pm

Do you have the speakers in some kind of enclosure? That might help to make them louder. You can also try bumping up the gain. The default is 6bB, but you can get 9dB by cutting this trace:
gain.jpg
gain.jpg (8.44 KiB) Viewed 48 times


Unfortunately, you won't be able to tie the output of the Speaker Bonnet to the MAX9744. The Speaker Bonnet is also I2S (not I2C), so there isn't any line level output available. You'll need to use something else to get a line level output. Options are HDMI (would need a cable breakout), the analog audio on the phono jack (very low quality), or some kind of DAC, like this cheap USB dongle:
https://www.adafruit.com/product/1475

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Re: MAX9744 inputs

by crossoft on Thu Aug 08, 2019 7:13 pm

Hello, I actually do have the speaker enclosed, it's just terribly quiet :)

I'll try the USB dongle - since I need line level output to the amplifier, is there a way via I2C to manage the volume of the amplifier then? I'm inexperienced in it, but hoping to control it via aplay or node js.

Thanks!!

crossoft
 
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Joined: Thu Aug 08, 2019 3:47 pm

Re: MAX9744 inputs

by adafruit_support_carter on Thu Aug 08, 2019 8:04 pm

Yep, you can control the amp over I2C. See the Digital Control sections that show the general approach with Arduino:
https://learn.adafruit.com/adafruit-20w ... al-control
or CircuitPython:
https://learn.adafruit.com/adafruit-20w ... cuitpython

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Please be positive and constructive with your questions and comments.