diff --git a/ai-hub/app/api/routes/tts.py b/ai-hub/app/api/routes/tts.py
index 5352008..9e3d620 100644
--- a/ai-hub/app/api/routes/tts.py
+++ b/ai-hub/app/api/routes/tts.py
@@ -134,7 +134,7 @@
                         
                         # Then stream the remaining chunks using parallel fetching but sequential yielding
                         import asyncio
-                        semaphore = asyncio.Semaphore(3) # Limit concurrent external requests
+                        semaphore = asyncio.Semaphore(1) # Strict lock for Beta TTS stability
 
                         async def fetch_chunk(text_chunk, idx):
                             retries = 3
@@ -143,7 +143,6 @@
                                 try:
                                     async with semaphore:
                                         pcm_data = await provider.generate_speech(text_chunk)
-                                        logger.debug(f"TTS Chunk {idx} generated: {len(pcm_data)} bytes.")
                                         return pcm_data
                                 except Exception as e:
                                     error_str = str(e)
@@ -168,7 +167,7 @@
                                     yield _create_wav_file(pcm)
                                 else:
                                     yield pcm
-                                logger.debug(f"TTS Chunk {i+1} yielded.")
+                                logger.info(f"TTS Chunk {i+1} yielded successfully.")
                                 
                     except Exception as e:
                         logger.error(f"Runtime error in TTS stream: {e}")
@@ -176,7 +175,7 @@
                     finally:
                         logger.info(f"TTS Stream finished for session {user_id}")
 
-                media_type = "audio/wav" if as_wav else "application/octet-stream"
+                media_type = "audio/wav" if as_wav else "audio/wav" # Keep as wav for best client support
                 return StreamingResponse(
                     full_stream(), 
                     media_type=media_type, 
diff --git a/ai-hub/app/core/providers/tts/gemini.py b/ai-hub/app/core/providers/tts/gemini.py
index c5353d9..b3a207c 100644
--- a/ai-hub/app/core/providers/tts/gemini.py
+++ b/ai-hub/app/core/providers/tts/gemini.py
@@ -78,7 +78,7 @@
         before_sleep=lambda retry_state: logger.warning(f"Retrying Gemini TTS request (attempt {retry_state.attempt_number})...")
     )
     async def generate_speech(self, text: str) -> bytes:
-        logger.debug(f"TTS generate_speech: '{text[:60]}...'")
+        logger.info(f"TTS request [model={self.model_name}, vertex={self.is_vertex}]: '{text}'")
 
         headers = {"Content-Type": "application/json"}