diff --git a/light9/effect/sequencer/eval_faders.py b/light9/effect/sequencer/eval_faders.py
--- a/light9/effect/sequencer/eval_faders.py
+++ b/light9/effect/sequencer/eval_faders.py
@@ -44,8 +44,10 @@ class FaderEval:
         self.graph = graph
         self.lib = lib
         self.faders: List[Fader] = []
+        self.grandMaster = 1.0
 
         self.graph.addHandler(self._compile)
+        self.graph.addHandler(self._compileGm)
         self.lastLoopSucceeded = False
 
     @COMPILE.time()
@@ -73,6 +75,15 @@ class FaderEval:
         setAttr = typedValue(EffectAttr, self.graph, setting, L9['effectAttr'])
         return (Fader(self.graph, self.lib, cast(URIRef, fader), effect, setAttr))
 
+    def _compileGm(self):
+        try:
+            self.grandMaster = typedValue(float, self.graph,
+                                          L9.grandMaster,
+                                          L9.value)
+            print('got gm', self.grandMaster)
+        except ValueError:
+            return
+        
     @COMPUTE_ALL_FADERS.time()
     def computeOutput(self) -> DeviceSettings:
         faderEffectOutputs: List[DeviceSettings] = []
@@ -82,7 +93,9 @@ class FaderEval:
                 if f.value is None:
                     log.warning(f'{f.value=}; should be set during _compile. Skipping {f.uri}')
                     continue
-                effectSettings = EffectSettings(self.graph, [(f.effect, f.setEffectAttr, f.value)])
+                v = f.value
+                v *= self.grandMaster
+                effectSettings = EffectSettings(self.graph, [(f.effect, f.setEffectAttr, v)])
 
                 ds = f.ee.compute(now, effectSettings)
                 faderEffectOutputs.append(ds)