diff --git a/src/engine/platform/sound/ymfm/ymfm_opz.h b/src/engine/platform/sound/ymfm/ymfm_opz.h
index 997ba32f9..4bc4663a0 100644
--- a/src/engine/platform/sound/ymfm/ymfm_opz.h
+++ b/src/engine/platform/sound/ymfm/ymfm_opz.h
@@ -220,8 +220,8 @@ public:
 
 	// per-channel registers
 	uint32_t ch_volume(uint32_t choffs) const        { return byte(0x00, 0, 8, choffs); }
-	uint32_t ch_output_any(uint32_t choffs) const    { return byte(0x20, 7, 1, choffs) | byte(0x30, 0, 1, choffs); }
-	uint32_t ch_output_0(uint32_t choffs) const      { return byte(0x30, 0, 1, choffs); }
+	uint32_t ch_output_any(uint32_t choffs) const    { return 1; }
+	uint32_t ch_output_0(uint32_t choffs) const      { return byte(0x30, 0, 1, choffs) | (!byte(0x20, 7, 1, choffs)); }
 	uint32_t ch_output_1(uint32_t choffs) const      { return byte(0x20, 7, 1, choffs) | byte(0x30, 0, 1, choffs); }
 	uint32_t ch_output_2(uint32_t choffs) const      { return 0; }
 	uint32_t ch_output_3(uint32_t choffs) const      { return 0; }
diff --git a/src/engine/platform/tx81z.cpp b/src/engine/platform/tx81z.cpp
index f81fda5fe..e9e817cd7 100644
--- a/src/engine/platform/tx81z.cpp
+++ b/src/engine/platform/tx81z.cpp
@@ -490,6 +490,7 @@ int DivPlatformTX81Z::dispatch(DivCommand c) {
     case DIV_CMD_PANNING: {
       chan[c.chan].chVolL=((c.value>>4)>0);
       chan[c.chan].chVolR=((c.value&15)>0);
+      chan[c.chan].freqChanged=true;
       /*
       if (isMuted[c.chan]) {
         rWrite(chanOffs[c.chan]+ADDR_LR_FB_ALG,(chan[c.chan].state.alg&7)|(chan[c.chan].state.fb<<3));
diff --git a/src/engine/playback.cpp b/src/engine/playback.cpp
index 3b382de80..8e1f1d664 100644
--- a/src/engine/playback.cpp
+++ b/src/engine/playback.cpp
@@ -479,6 +479,7 @@ bool DivEngine::perSystemEffect(int ch, unsigned char effect, unsigned char effe
 }
 
 #define IS_YM2610 (sysOfChan[ch]==DIV_SYSTEM_YM2610 || sysOfChan[ch]==DIV_SYSTEM_YM2610_EXT || sysOfChan[ch]==DIV_SYSTEM_YM2610_FULL || sysOfChan[ch]==DIV_SYSTEM_YM2610_FULL_EXT || sysOfChan[ch]==DIV_SYSTEM_YM2610B || sysOfChan[ch]==DIV_SYSTEM_YM2610B_EXT)
+#define IS_OPM_LIKE (sysOfChan[ch]==DIV_SYSTEM_YM2151 || sysOfChan[ch]==DIV_SYSTEM_OPZ)
 
 bool DivEngine::perSystemPostEffect(int ch, unsigned char effect, unsigned char effectVal) {
   switch (sysOfChan[ch]) {
@@ -491,9 +492,10 @@ bool DivEngine::perSystemPostEffect(int ch, unsigned char effect, unsigned char
     case DIV_SYSTEM_YM2610_FULL_EXT:
     case DIV_SYSTEM_YM2610B:
     case DIV_SYSTEM_YM2610B_EXT:
+    case DIV_SYSTEM_OPZ:
       switch (effect) {
         case 0x10: // LFO or noise mode
-          if (sysOfChan[ch]==DIV_SYSTEM_YM2151) {
+          if (IS_OPM_LIKE) {
             dispatchCmd(DivCommand(DIV_CMD_STD_NOISE_FREQ,ch,effectVal));
           } else {
             dispatchCmd(DivCommand(DIV_CMD_FM_LFO,ch,effectVal));
@@ -520,12 +522,12 @@ bool DivEngine::perSystemPostEffect(int ch, unsigned char effect, unsigned char
           }
           break;
         case 0x17: // arcade LFO
-          if (sysOfChan[ch]==DIV_SYSTEM_YM2151) {
+          if (IS_OPM_LIKE) {
             dispatchCmd(DivCommand(DIV_CMD_FM_LFO,ch,effectVal));
           }
           break;
         case 0x18: // EXT or LFO waveform
-          if (sysOfChan[ch]==DIV_SYSTEM_YM2151) {
+          if (IS_OPM_LIKE) {
             dispatchCmd(DivCommand(DIV_CMD_FM_LFO_WAVE,ch,effectVal));
           } else {
             dispatchCmd(DivCommand(DIV_CMD_FM_EXTCH,ch,effectVal));