diff --git a/internal_filesystem/lib/mpos/audio/stream_wav.py b/internal_filesystem/lib/mpos/audio/stream_wav.py
index 7516dbae..c2a672c4 100644
--- a/internal_filesystem/lib/mpos/audio/stream_wav.py
+++ b/internal_filesystem/lib/mpos/audio/stream_wav.py
@@ -328,7 +328,8 @@ class WAVStream:
                     self._find_data_chunk(f)
 
                 # Decide playback rate (force >=22050 Hz) - but why?! the DAC should support down to 8kHz!
-                target_rate = 22050
+                target_rate = 22050 # slower is faster (less data)
+                target_rate = 22050 * 2 # CJC only supports 30kHz and up?
                 if original_rate >= target_rate:
                     playback_rate = original_rate
                     upsample_factor = 1
@@ -345,6 +346,25 @@ class WAVStream:
                 # Initialize I2S (always 16-bit output)
                 try:
                     i2s_format = machine.I2S.MONO if channels == 1 else machine.I2S.STEREO
+
+                    # Configure MCLK pin if provided (must be done before I2S init)
+                    # On some MicroPython versions, machine.I2S() supports a mck argument
+                    # but not on ESP32S3 1.25.0 version, apparently.
+                    if 'mck' in self.i2s_pins:
+                        mck_pin = machine.Pin(self.i2s_pins['mck'], machine.Pin.OUT)
+                        from machine import Pin, PWM
+                        # Add MCLK generation on GPIO2
+                        try:
+                            mck_pwm = PWM(mck_pin)
+                            # Set frequency to sample_rate * 256 (common ratio for CJC4334H auto-detect)
+                            # Use duty_u16 for finer control (0–65535 range, 32768 = 50%)
+                            mck_pwm.freq(playback_rate * 256)
+                            mck_pwm.duty_u16(32768)  # 50% duty cycle
+                            print(f"MCLK PWM started on GPIO2 at {playback_rate * 256} Hz")
+                        except Exception as e:
+                            print(f"MCLK PWM init failed: {e}")
+                            # fallback or error handling
+
                     self._i2s = machine.I2S(
                         0,
                         sck=machine.Pin(self.i2s_pins['sck'], machine.Pin.OUT),
diff --git a/internal_filesystem/lib/mpos/board/fri3d_2026.py b/internal_filesystem/lib/mpos/board/fri3d_2026.py
index 4e660553..ffaaae7f 100644
--- a/internal_filesystem/lib/mpos/board/fri3d_2026.py
+++ b/internal_filesystem/lib/mpos/board/fri3d_2026.py
@@ -211,15 +211,24 @@ from mpos import AudioManager
 # Note: I2S is created per-stream, not at boot (only one instance can exist)
 # The DAC uses BCK (bit clock) on GPIO 2, while the microphone uses SCLK on GPIO 17
 # See schematics: DAC has BCK=2, WS=47, SD=16; Microphone has SCLK=17, WS=47, DIN=15
+
+# This worked briefly, way too loud and with distortion:
 i2s_pins = {
-    # Output (DAC/speaker) pins
     'sck': 2,       # SCLK or BCLK (optional)
     'ws': 47,       # Word Select / LRCLK shared between DAC and mic (mandatory)
     'sd': 16,       # Serial Data OUT (speaker/DAC)
-    # Input (microphone) pins
     'sck_in': 17,   # SCLK - Serial Clock for microphone input (optional for audio out)
 }
 
+# This is how it should be (untested)
+i2s_pins = {
+    # Output (DAC/speaker) pins
+    'mck': 2,       # MCLK (mandatory)
+    #'sck': 17,      # SCLK or BCLK (optional)
+    'ws': 47,       # Word Select / LRCLK shared between DAC and mic (mandatory)
+    'sd': 16,       # Serial Data OUT (speaker/DAC)
+}
+
 # Initialize AudioManager with I2S (buzzer TODO)
 AudioManager(i2s_pins=i2s_pins)