diff --git a/src/lerobot/microphones/portaudio/microphone_portaudio.py b/src/lerobot/microphones/portaudio/microphone_portaudio.py
index 25f4a8a66..106f9060d 100644
--- a/src/lerobot/microphones/portaudio/microphone_portaudio.py
+++ b/src/lerobot/microphones/portaudio/microphone_portaudio.py
@@ -197,10 +197,11 @@ class PortAudioMicrophone(Microphone):
         # Can only be run on a single process/thread for file writing safety
         with sf.SoundFile(
             output_file,
-            mode="x",
+            mode="w",
             samplerate=sample_rate,
             channels=max(channels),
-            subtype=sf.default_subtype(output_file.suffix[1:]),
+            format="WAV",
+            subtype="FLOAT",  # By default, a much lower quality WAV file is created !
         ) as file:
             while not event.is_set():
                 try: