Speaker pHAT sound deterioration


After following the setup instructions for the “Adafruit MAX98357 I2S Class-D Mono Amp”, I had this HAT working, The sound level, seemed about right for a reputed 0.5W output. After an hour or so, the audio became overlaid with what sounded like digital noise almost masking the original source. Suspecting software issues, I laid the HAT aside until I found your single line installation instruction.

Fresh installation of Raspian Jessie (2017-1-11), the obligatory update & dist-upgrade, then your single-line install: The sound output is very low, the “left, right,…”. of speaker-test -c2 -t wav being barely perceptible more than 1 foot from the speaker; using Mathematica to generate a pure sinewave tone, the resultant is horribly noisy and distorted. Is this more likely to be hardware or software related?

Speaker Phat sound diminished

using alsamixer, make sure the output level is at 80+… not sure if that’s the issue but it sounds like it could be.


alsamixer playback level is set to 100.


I’ve just completed a fresh install on another RPi, same as before, plenty of lights, little sound.


have you soldered the pHAT onto the header? are you using select wiring or popping the pHAT onto the Pi as expected? can you post a picture of your setup for us?


Yes the pHAT is soldered onto the header. Image shows the pHAT attached to a RPi 2B, the problem remains whether I use a model 2, 3 or zero.


I can’t see anything wrong with the soldering.

… I’m not convinced it is hardware related if you had a respectable volume initially, but if you tried on a clean install with our software stack then that’s still the most plausible.

please, send an email to support@pimoroni.com and request a RMA, they will swap the unit and hopefully that will be the end of your troubles!


just to check though, have you seen the assembly guide and have followed it to mount and wire the speaker on the underside right?



Four nuts as spacers - ✔
Soldering looks OK - ✔

Guess, I’ll have to RMA it.