diff --git a/Models/Instruments/Audio/Audio1.xml b/Models/Instruments/Audio/Audio1.xml
index d1f7391f..3faf04a2 100644
--- a/Models/Instruments/Audio/Audio1.xml
+++ b/Models/Instruments/Audio/Audio1.xml
@@ -980,7 +980,7 @@
 						<value>25</value>
 					</greater-than-equals>
 					<equals>
-						<property>systems/audio/acp[1]/call_chan</property>
+						<property>systems/audio/acp[0]/call_chan</property>
 						<value type="string">hf1</value>
 					</equals>
 				</and>