diff --git a/tortoise/api.py b/tortoise/api.py
index c4cce4d..11a13ff 100644
--- a/tortoise/api.py
+++ b/tortoise/api.py
@@ -280,10 +280,10 @@ class TextToSpeech:
                        'cond_free_k': 2.0, 'diffusion_temperature': 1.0})
         # Presets are defined here.
         presets = {
-            'ultra_fast': {'num_autoregressive_samples': 16, 'diffusion_iterations': 32, 'cond_free': False},
-            'fast': {'num_autoregressive_samples': 96, 'diffusion_iterations': 32},
-            'standard': {'num_autoregressive_samples': 256, 'diffusion_iterations': 128},
-            'high_quality': {'num_autoregressive_samples': 512, 'diffusion_iterations': 1024},
+            'ultra_fast': {'num_autoregressive_samples': 16, 'diffusion_iterations': 30, 'cond_free': False},
+            'fast': {'num_autoregressive_samples': 96, 'diffusion_iterations': 80},
+            'standard': {'num_autoregressive_samples': 256, 'diffusion_iterations': 200},
+            'high_quality': {'num_autoregressive_samples': 256, 'diffusion_iterations': 400},
         }
         kwargs.update(presets[preset])
         return self.tts(text, **kwargs)