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Adafruit MAX98357 I2S Class-D Mono Amp Tips
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Adafruit MAX98357 I2S Class-D Mono Amp Tips

by aer0usa on Wed Feb 10, 2021 9:39 am

Hi. Instead of a question, I'm here to share some tips that I found when working with my Adafruit MAX98357 I2S Class-D Mono Amp.

I followed the setup instructions for the amp, and I thought that rather than run the provided script, I'd follow the "Detailed Install", but I think that the Detailed Install skips something, because it didn't work. So I ran the provided script and then it was fine. I haven't actually gone and checked the content of the script to see what it adds. Probably a driver? Anyway, just so you know, check out the script. It doesn't seem to hurt anything if you run the script after doing the Detailed Install.

Then, once I had it playing audio, the audio was very scratchy. I was thinking something was wrong with the speaker or I had a loose connection or bad solder joints. Well, I had left the "Gain" pin unconnected because I figured the default of 9dB would be fine. On a whim, I connected the Gain pin to the Gnd (for 12dB), and the scratchiness went away! Now it sounds great! Something to try if you don't like the audio quality.

While I was trying to figure out the audio problem, I found the "downsampling" arguments for mpg123. Once I had the Gain figured out, I found that downsampling with the "-4" argument made the audio sound even better! Try "mpg123 --help" for more arguments. The downsampling didn't help with the scratchiness; that was the Gain pin. Your mileage may vary, but it is worth trying.

That's it! This amp is a great way to play audio out of a Raspberry Pi Zero W!

aer0usa
 
Posts: 1
Joined: Tue Feb 09, 2021 6:17 pm

Re: Adafruit MAX98357 I2S Class-D Mono Amp Tips

by Clyde256 on Thu Apr 29, 2021 1:14 am

Thank you for sharing your experience. Don't have a problem with the volume control? The official Adafruit manual states that this problem exists. Did you solve it somehow?

Clyde256
 
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Joined: Thu Apr 29, 2021 1:11 am

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