diff --git a/src/dexed.cpp b/src/dexed.cpp
index f6d5bbf..e8ba337 100644
--- a/src/dexed.cpp
+++ b/src/dexed.cpp
@@ -92,7 +92,8 @@ Dexed::Dexed(double rate) : lvtk::Synth<DexedVoice, Dexed>(p_n_ports, p_midi_in)
   controllers.breath_cc = 0;
   controllers.aftertouch_cc = 0;
   controllers.masterTune=0;
-  controllers.opSwitch=0x3f; // enable all operators
+  //controllers.opSwitch=0x3f; // enable all operators
+  controllers.opSwitch=0x00;
 
   bufsize_=256;
 
@@ -796,12 +797,22 @@ void Dexed::onParam(uint8_t param_num,float param_val)
         controllers.masterTune=(tune<<11)*(1.0/12);
         break;
       case 166:
+        controllers.opSwitch|=data[param_num]<<5;
+        break;
       case 167:
+        controllers.opSwitch|=data[param_num]<<4;
+        break;
       case 168:
+        controllers.opSwitch|=data[param_num]<<3;
+        break;
       case 169:
+        controllers.opSwitch|=data[param_num]<<2;
+        break;
       case 170:
+        controllers.opSwitch|=data[param_num]<<1;
+        break;
       case 171:
-        controllers.opSwitch=(data[166]<<5)|(data[167]<<4)|(data[168]<<3)|(data[169]<<2)|(data[170]<<1)|data[171];
+        controllers.opSwitch|=data[param_num];
         break;
       case 172:
         max_notes=data[param_num];