diff --git a/src/engine/platform/opl.cpp b/src/engine/platform/opl.cpp
index d453dab2..fe446ad2 100644
--- a/src/engine/platform/opl.cpp
+++ b/src/engine/platform/opl.cpp
@@ -349,10 +349,21 @@ void DivPlatformOPL::tick() {
 
     if (chan[i].keyOn || chan[i].keyOff) {
       immWrite(chanMap[i]+ADDR_FREQH,0x00|(chan[i].freqH&31));
+      if (chan[i].state.ops==4 && i<6) {
+        immWrite(chanMap[i+1]+ADDR_FREQH,0x00|(chan[i].freqH&31));
+      }
       chan[i].keyOff=false;
     }
   }
 
+  if (update4OpMask) {
+    update4OpMask=false;
+    if (oplType==3) {
+      unsigned char opMask=chan[0].fourOp|(chan[2].fourOp<<1)|(chan[4].fourOp<<2)|(chan[6].fourOp<<3)|(chan[8].fourOp<<4)|(chan[10].fourOp<<5);
+      rWrite(0x104,opMask);
+    }
+  }
+
   for (int i=0; i<512; i++) {
     if (pendingWrites[i]!=oldWrites[i]) {
       immWrite(i,pendingWrites[i]&0xff);
@@ -368,12 +379,21 @@ void DivPlatformOPL::tick() {
       chan[i].freqH=freqt>>8;
       chan[i].freqL=freqt&0xff;
       immWrite(chanMap[i]+ADDR_FREQ,chan[i].freqL);
+      if (chan[i].state.ops==4 && i<6) {
+        immWrite(chanMap[i+1]+ADDR_FREQ,chan[i].freqL);
+      }
     }
     if (chan[i].keyOn) {
       immWrite(chanMap[i]+ADDR_FREQH,chan[i].freqH|(0x20));
+      if (chan[i].state.ops==4 && i<6) {
+        immWrite(chanMap[i+1]+ADDR_FREQH,chan[i].freqH|(0x20));
+      }
       chan[i].keyOn=false;
     } else if (chan[i].freqChanged) {
       immWrite(chanMap[i]+ADDR_FREQH,chan[i].freqH|(chan[i].active<<5));
+      if (chan[i].state.ops==4 && i<6) {
+        immWrite(chanMap[i+1]+ADDR_FREQH,chan[i].freqH|(chan[i].active<<5));
+      }
     }
     chan[i].freqChanged=false;
   }
@@ -457,6 +477,8 @@ int DivPlatformOPL::dispatch(DivCommand c) {
       }
       if (chan[c.chan].insChanged) {
         int ops=(slots[3][c.chan]!=255 && chan[c.chan].state.ops==4 && oplType==3)?4:2;
+        chan[c.chan].fourOp=(ops==4);
+        update4OpMask=true;
         for (int i=0; i<ops; i++) {
           unsigned char slot=slots[i][c.chan];
           if (slot==255) continue;
@@ -554,16 +576,22 @@ int DivPlatformOPL::dispatch(DivCommand c) {
       chan[c.chan].ins=c.value;
       break;
     case DIV_CMD_PANNING: {
-      switch (c.value) {
-        case 0x01:
-          chan[c.chan].pan=1;
-          break;
-        case 0x10:
-          chan[c.chan].pan=2;
-          break;
-        default:
-          chan[c.chan].pan=3;
-          break;
+      if (c.value==0) {
+        chan[c.chan].pan=3;
+      } else {
+        chan[c.chan].pan=(((c.value&15)>0)<<1)|((c.value>>4)>0);
+      }
+      int ops=(slots[3][c.chan]!=255 && chan[c.chan].state.ops==4 && oplType==3)?4:2;
+      if (isMuted[c.chan]) {
+        rWrite(chanMap[c.chan]+ADDR_LR_FB_ALG,(chan[c.chan].state.alg&1)|(chan[c.chan].state.fb<<1));
+        if (ops==4) {
+          rWrite(chanMap[c.chan+1]+ADDR_LR_FB_ALG,((chan[c.chan].state.alg>>1)&1)|(chan[c.chan].state.fb<<1));
+        }
+      } else {
+        rWrite(chanMap[c.chan]+ADDR_LR_FB_ALG,(chan[c.chan].state.alg&1)|(chan[c.chan].state.fb<<1)|((chan[c.chan].pan&3)<<4));
+        if (ops==4) {
+          rWrite(chanMap[c.chan+1]+ADDR_LR_FB_ALG,((chan[c.chan].state.alg>>1)&1)|(chan[c.chan].state.fb<<1)|((chan[c.chan].pan&3)<<4));
+        }
       }
       //rWrite(chanOffs[c.chan]+ADDR_LRAF,(isMuted[c.chan]?0:(chan[c.chan].pan<<6))|(chan[c.chan].state.fms&7)|((chan[c.chan].state.ams&3)<<4));
       break;
@@ -687,6 +715,7 @@ int DivPlatformOPL::dispatch(DivCommand c) {
 void DivPlatformOPL::forceIns() {
   for (int i=0; i<18; i++) {
     int ops=(slots[3][i]!=255 && chan[i].state.ops==4 && oplType==3)?4:2;
+    chan[i].fourOp=(ops==4);
     for (int j=0; j<ops; j++) {
       unsigned char slot=slots[j][i];
       if (slot==255) continue;
@@ -723,6 +752,7 @@ void DivPlatformOPL::forceIns() {
       }
     }
   }
+  update4OpMask=true;
 }
 
 void DivPlatformOPL::toggleRegisterDump(bool enable) {
@@ -768,10 +798,15 @@ void DivPlatformOPL::reset() {
   lfoValue=8;
   properDrums=properDrumsSys;
 
+  if (oplType==1) { // disable waveforms
+    immWrite(0x01,0x20);
+  }
+
   if (oplType==3) { // enable OPL3 features
     immWrite(0x105,1);
   }
-  
+
+  update4OpMask=true;
   delay=0;
 }
 
diff --git a/src/engine/platform/opl.h b/src/engine/platform/opl.h
index 7bd6118a..3515b29e 100644
--- a/src/engine/platform/opl.h
+++ b/src/engine/platform/opl.h
@@ -32,7 +32,7 @@ class DivPlatformOPL: public DivDispatch {
       unsigned char freqH, freqL;
       int freq, baseFreq, pitch, note;
       unsigned char ins;
-      bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, furnaceDac, inPorta;
+      bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, furnaceDac, inPorta, fourOp;
       int vol, outVol;
       unsigned char pan;
       Channel():
@@ -51,6 +51,7 @@ class DivPlatformOPL: public DivDispatch {
         portaPause(false),
         furnaceDac(false),
         inPorta(false),
+        fourOp(false),
         vol(0),
         pan(3) {}
     };
@@ -78,7 +79,7 @@ class DivPlatformOPL: public DivDispatch {
 
     unsigned char lfoValue;
 
-    bool useYMFM;
+    bool useYMFM, update4OpMask;
   
     short oldWrites[512];
     short pendingWrites[512];