diff --git a/dont_fret/models.py b/dont_fret/models.py
index b56299b..170b824 100644
--- a/dont_fret/models.py
+++ b/dont_fret/models.py
@@ -11,7 +11,8 @@
 
 from dont_fret.burst_search import bs_eggeling, return_intersections
 from dont_fret.channel_kde import compute_alex_2cde, compute_fret_2cde, convolve_stream, make_kernel
-from dont_fret.config.config import BurstColor, DontFRETConfig, cfg
+from dont_fret.config import cfg as global_cfg
+from dont_fret.config.config import BurstColor, DontFRETConfig
 from dont_fret.support import get_binned
 from dont_fret.utils import clean_types
 
@@ -34,7 +35,7 @@ class PhotonData:
     """
 
     def __init__(
-        self, data: pl.DataFrame, metadata: Optional[dict] = None, cfg: DontFRETConfig = cfg
+        self, data: pl.DataFrame, metadata: Optional[dict] = None, cfg: DontFRETConfig = global_cfg
     ):
         self.data = data
         self.metadata = metadata or {}
@@ -224,7 +225,7 @@ def burst_search(self, colors: Union[str, list[BurstColor]]) -> Bursts:
         """
 
         if isinstance(colors, str):
-            burst_colors = cfg.burst_search[colors]
+            burst_colors = global_cfg.burst_search[colors]
         elif isinstance(colors, list):
             burst_colors = colors
         else:
@@ -380,7 +381,7 @@ def from_photons(
         cls,
         photon_data: pl.DataFrame,
         metadata: Optional[dict] = None,
-        cfg: DontFRETConfig = cfg,
+        cfg: DontFRETConfig = global_cfg,
     ) -> Bursts:
         # todo move to classmethod
 
@@ -446,7 +447,10 @@ def load(cls, directory: Path) -> Bursts:
         with open(directory / "metadata.json", "r") as f:
             metadata = json.load(f)
 
-        cfg = DontFRETConfig.from_yaml(directory / "config.yaml")
+        try:
+            cfg = DontFRETConfig.from_yaml(directory / "config.yaml")
+        except FileNotFoundError:
+            cfg = None
         return Bursts(burst_data, photon_data, metadata, cfg)
 
     def save(self, directory: Path) -> None:
@@ -456,7 +460,8 @@ def save(self, directory: Path) -> None:
 
         with open(directory / "metadata.json", "w") as f:
             json.dump(self.metadata, f)
-        self.cfg.to_yaml(directory / "config.yaml")
+        if self.cfg is not None:
+            self.cfg.to_yaml(directory / "config.yaml")
 
     def fret_2cde(self, photons: PhotonData, tau: float = 50e-6) -> Bursts:
         assert photons.timestamps_unit