diff --git a/src/engine/dispatch.h b/src/engine/dispatch.h
index 37a001b2..4574ebb9 100644
--- a/src/engine/dispatch.h
+++ b/src/engine/dispatch.h
@@ -453,18 +453,6 @@ class DivDispatch {
      */
     virtual bool getWantPreNote();
 
-    /**
-     * get minimum chip clock.
-     * @return clock in Hz, or 0 if custom clocks are not supported.
-     */
-    virtual unsigned int getClockRangeMin();
-
-    /**
-     * get maximum chip clock.
-     * @return clock in Hz, or 0 if custom clocks are not supported.
-     */
-    virtual unsigned int getClockRangeMax();
-
     /**
      * set the chip flags.
      * @param flags a DivConfig containing chip flags.
@@ -591,6 +579,14 @@ class DivDispatch {
     virtual ~DivDispatch();
 };
 
+// custom chip clock helper define. put in setFlags, but before rate is set.
+#define CHECK_CUSTOM_CLOCK \
+  if (flags.getInt("customClock",0)>0) { \
+    chipClock=flags.getInt("customClock",1000000); \
+    if (chipClock>20000000) chipClock=20000000; \
+    if (chipClock<100000) chipClock=100000; \
+  }
+
 // pitch calculation:
 // - a DivDispatch usually contains four variables per channel:
 //   - baseFreq: this changes on new notes, legato, arpeggio and slides.
diff --git a/src/engine/platform/abstract.cpp b/src/engine/platform/abstract.cpp
index 8ee1d45a..33dd3c17 100644
--- a/src/engine/platform/abstract.cpp
+++ b/src/engine/platform/abstract.cpp
@@ -97,14 +97,6 @@ bool DivDispatch::getWantPreNote() {
   return false;
 }
 
-unsigned int DivDispatch::getClockRangeMin() {
-  return 0;
-}
-
-unsigned int DivDispatch::getClockRangeMax() {
-  return 0;
-}
-
 void DivDispatch::setFlags(const DivConfig& flags) {
 }
 
diff --git a/src/engine/platform/ay.cpp b/src/engine/platform/ay.cpp
index ab2c2c72..b10cdfd8 100644
--- a/src/engine/platform/ay.cpp
+++ b/src/engine/platform/ay.cpp
@@ -826,6 +826,7 @@ void DivPlatformAY8910::setFlags(const DivConfig& flags) {
         chipClock=COLOR_NTSC/2.0;
         break;
     }
+    CHECK_CUSTOM_CLOCK;
     rate=chipClock/8;
   }
   for (int i=0; i<3; i++) {
diff --git a/src/engine/platform/ay8930.cpp b/src/engine/platform/ay8930.cpp
index 821fa4fe..2ec70048 100644
--- a/src/engine/platform/ay8930.cpp
+++ b/src/engine/platform/ay8930.cpp
@@ -804,6 +804,7 @@ void DivPlatformAY8930::setFlags(const DivConfig& flags) {
       chipClock=COLOR_NTSC/2.0;
       break;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/4;
   for (int i=0; i<3; i++) {
     oscBuf[i]->rate=rate;
diff --git a/src/engine/platform/bubsyswsg.cpp b/src/engine/platform/bubsyswsg.cpp
index c00b4ce2..a43b8b1d 100644
--- a/src/engine/platform/bubsyswsg.cpp
+++ b/src/engine/platform/bubsyswsg.cpp
@@ -323,6 +323,7 @@ void DivPlatformBubSysWSG::notifyInsDeletion(void* ins) {
 
 void DivPlatformBubSysWSG::setFlags(const DivConfig& flags) {
   chipClock=COLOR_NTSC;
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock;
   for (int i=0; i<2; i++) {
     oscBuf[i]->rate=rate/64;
diff --git a/src/engine/platform/c64.cpp b/src/engine/platform/c64.cpp
index 9fb10d41..068dd1b3 100644
--- a/src/engine/platform/c64.cpp
+++ b/src/engine/platform/c64.cpp
@@ -535,17 +535,18 @@ void DivPlatformC64::setFP(bool fp) {
 void DivPlatformC64::setFlags(const DivConfig& flags) {
   switch (flags.getInt("clockSel",0)) {
     case 0x0: // NTSC C64
-      rate=COLOR_NTSC*2.0/7.0;
+      chipClock=COLOR_NTSC*2.0/7.0;
       break;
     case 0x1: // PAL C64
-      rate=COLOR_PAL*2.0/9.0;
+      chipClock=COLOR_PAL*2.0/9.0;
       break;
     case 0x2: // SSI 2001
     default:
-      rate=14318180.0/16.0;
+      chipClock=14318180.0/16.0;
       break;
   }
-  chipClock=rate;
+  CHECK_CUSTOM_CLOCK;
+  rate=chipClock;
   for (int i=0; i<3; i++) {
     oscBuf[i]->rate=rate/16;
   }
diff --git a/src/engine/platform/fds.cpp b/src/engine/platform/fds.cpp
index 5859be56..ab4c228a 100644
--- a/src/engine/platform/fds.cpp
+++ b/src/engine/platform/fds.cpp
@@ -454,13 +454,14 @@ void DivPlatformFDS::setNSFPlay(bool use) {
 void DivPlatformFDS::setFlags(const DivConfig& flags) {
   int clockSel=flags.getInt("clockSel",0);
   if (clockSel==2) { // Dendy
-    rate=COLOR_PAL*2.0/5.0;
+    chipClock=COLOR_PAL*2.0/5.0;
   } else if (clockSel==1) { // PAL
-    rate=COLOR_PAL*3.0/8.0;
+    chipClock=COLOR_PAL*3.0/8.0;
   } else { // NTSC
-    rate=COLOR_NTSC/2.0;
+    chipClock=COLOR_NTSC/2.0;
   }
-  chipClock=rate;
+  CHECK_CUSTOM_CLOCK;
+  rate=chipClock;
   oscBuf->rate=rate/32;
   if (useNP) {
     fds_NP->SetClock(rate);
diff --git a/src/engine/platform/gb.cpp b/src/engine/platform/gb.cpp
index 6a88d0f7..0bdd2434 100644
--- a/src/engine/platform/gb.cpp
+++ b/src/engine/platform/gb.cpp
@@ -655,6 +655,7 @@ void DivPlatformGB::setFlags(const DivConfig& flags) {
 
 int DivPlatformGB::init(DivEngine* p, int channels, int sugRate, const DivConfig& flags) {
   chipClock=4194304;
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/16;
   for (int i=0; i<4; i++) {
     isMuted[i]=false;
diff --git a/src/engine/platform/genesis.cpp b/src/engine/platform/genesis.cpp
index 85074228..adfdf258 100644
--- a/src/engine/platform/genesis.cpp
+++ b/src/engine/platform/genesis.cpp
@@ -1221,6 +1221,7 @@ void DivPlatformGenesis::setFlags(const DivConfig& flags) {
   ladder=flags.getBool("ladderEffect",false);
   noExtMacros=flags.getBool("noExtMacros",false);
   OPN2_SetChipType(ladder?ym3438_mode_ym2612:0);
+  CHECK_CUSTOM_CLOCK;
   if (useYMFM) {
     if (fm_ymfm!=NULL) delete fm_ymfm;
     if (ladder) {
diff --git a/src/engine/platform/lynx.cpp b/src/engine/platform/lynx.cpp
index 66acdcd5..e6704b64 100644
--- a/src/engine/platform/lynx.cpp
+++ b/src/engine/platform/lynx.cpp
@@ -471,6 +471,7 @@ int DivPlatformLynx::init(DivEngine* p, int channels, int sugRate, const DivConf
   }
 
   chipClock = 16000000;
+  CHECK_CUSTOM_CLOCK;
   rate = chipClock/128;
 
   for (int i=0; i<4; i++) {
diff --git a/src/engine/platform/mmc5.cpp b/src/engine/platform/mmc5.cpp
index b52017e8..9feaabfc 100644
--- a/src/engine/platform/mmc5.cpp
+++ b/src/engine/platform/mmc5.cpp
@@ -389,13 +389,14 @@ bool DivPlatformMMC5::keyOffAffectsArp(int ch) {
 void DivPlatformMMC5::setFlags(const DivConfig& flags) {
   int clockSel=flags.getInt("clockSel",0);
   if (clockSel==2) { // Dendy
-    rate=COLOR_PAL*2.0/5.0;
+    chipClock=COLOR_PAL*2.0/5.0;
   } else if (clockSel==1) { // PAL
-    rate=COLOR_PAL*3.0/8.0;
+    chipClock=COLOR_PAL*3.0/8.0;
   } else { // NTSC
-    rate=COLOR_NTSC/2.0;
+    chipClock=COLOR_NTSC/2.0;
   }
-  chipClock=rate;
+  CHECK_CUSTOM_CLOCK;
+  rate=chipClock;
   for (int i=0; i<3; i++) {
     oscBuf[i]->rate=rate/32;
   }
diff --git a/src/engine/platform/msm5232.cpp b/src/engine/platform/msm5232.cpp
index 84e8d91b..a9a70092 100644
--- a/src/engine/platform/msm5232.cpp
+++ b/src/engine/platform/msm5232.cpp
@@ -372,6 +372,7 @@ void DivPlatformMSM5232::notifyInsDeletion(void* ins) {
 
 void DivPlatformMSM5232::setFlags(const DivConfig& flags) {
   chipClock=2119040;
+  CHECK_CUSTOM_CLOCK;
   detune=flags.getInt("detune",0);
   msm->set_clock(chipClock+detune*1024);
   rate=msm->get_rate();
diff --git a/src/engine/platform/msm6258.cpp b/src/engine/platform/msm6258.cpp
index 7111c84c..ef11c717 100644
--- a/src/engine/platform/msm6258.cpp
+++ b/src/engine/platform/msm6258.cpp
@@ -412,6 +412,7 @@ void DivPlatformMSM6258::setFlags(const DivConfig& flags) {
       chipClock=4000000;
       break;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/256;
   for (int i=0; i<1; i++) {
     oscBuf[i]->rate=rate;
diff --git a/src/engine/platform/msm6295.cpp b/src/engine/platform/msm6295.cpp
index 71b8d7cf..3bf0b8eb 100644
--- a/src/engine/platform/msm6295.cpp
+++ b/src/engine/platform/msm6295.cpp
@@ -438,6 +438,7 @@ void DivPlatformMSM6295::setFlags(const DivConfig& flags) {
       chipClock=4000000/4;
       break;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/3;
   for (int i=0; i<4; i++) {
     oscBuf[i]->rate=rate/22;
diff --git a/src/engine/platform/n163.cpp b/src/engine/platform/n163.cpp
index 26d42e45..50da45f0 100644
--- a/src/engine/platform/n163.cpp
+++ b/src/engine/platform/n163.cpp
@@ -624,18 +624,19 @@ void DivPlatformN163::poke(std::vector<DivRegWrite>& wlist) {
 void DivPlatformN163::setFlags(const DivConfig& flags) {
   switch (flags.getInt("clockSel",0)) {
     case 1: // PAL
-      rate=COLOR_PAL*3.0/8.0;
+      chipClock=COLOR_PAL*3.0/8.0;
       break;
     case 2: // Dendy
-      rate=COLOR_PAL*2.0/5.0;
+      chipClock=COLOR_PAL*2.0/5.0;
       break;
     default: // NTSC
-      rate=COLOR_NTSC/2.0;
+      chipClock=COLOR_NTSC/2.0;
       break;
   }
+  CHECK_CUSTOM_CLOCK;
   initChanMax=chanMax=flags.getInt("channels",0)&7;
   multiplex=!flags.getBool("multiplex",false); // not accurate in real hardware
-  chipClock=rate;
+  rate=chipClock;
   rate/=15;
   n163.set_multiplex(multiplex);
   rWrite(0x7f,initChanMax<<4);
diff --git a/src/engine/platform/namcowsg.cpp b/src/engine/platform/namcowsg.cpp
index aab625b1..c1466b90 100644
--- a/src/engine/platform/namcowsg.cpp
+++ b/src/engine/platform/namcowsg.cpp
@@ -532,6 +532,7 @@ void DivPlatformNamcoWSG::setDeviceType(int type) {
 
 void DivPlatformNamcoWSG::setFlags(const DivConfig& flags) {
   chipClock=3072000;
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/32;
   namco->device_clock_changed(rate);
   for (int i=0; i<chans; i++) {
diff --git a/src/engine/platform/nes.cpp b/src/engine/platform/nes.cpp
index c971d4bf..87b2b9da 100644
--- a/src/engine/platform/nes.cpp
+++ b/src/engine/platform/nes.cpp
@@ -663,13 +663,13 @@ bool DivPlatformNES::keyOffAffectsArp(int ch) {
 void DivPlatformNES::setFlags(const DivConfig& flags) {
   int clockSel=flags.getInt("clockSel",0);
   if (clockSel==2) { // Dendy
-    rate=COLOR_PAL*2.0/5.0;
+    chipClock=COLOR_PAL*2.0/5.0;
     apuType=2;
   } else if (clockSel==1) { // PAL
-    rate=COLOR_PAL*3.0/8.0;
+    chipClock=COLOR_PAL*3.0/8.0;
     apuType=1;
   } else { // NTSC
-    rate=COLOR_NTSC/2.0;
+    chipClock=COLOR_NTSC/2.0;
     apuType=0;
   }
   if (useNP) {
@@ -681,7 +681,8 @@ void DivPlatformNES::setFlags(const DivConfig& flags) {
   } else {
     nes->apu.type=apuType;
   }
-  chipClock=rate;
+  CHECK_CUSTOM_CLOCK;
+  rate=chipClock;
   for (int i=0; i<5; i++) {
     oscBuf[i]->rate=rate/32;
   }
diff --git a/src/engine/platform/opl.cpp b/src/engine/platform/opl.cpp
index 5353fa6c..4464508c 100644
--- a/src/engine/platform/opl.cpp
+++ b/src/engine/platform/opl.cpp
@@ -1694,6 +1694,7 @@ void DivPlatformOPL::setFlags(const DivConfig& flags) {
           chipClock=COLOR_NTSC;
           break;
       }
+      CHECK_CUSTOM_CLOCK;
       rate=chipClock/72;
       chipRateBase=rate;
       break;
@@ -1715,6 +1716,7 @@ void DivPlatformOPL::setFlags(const DivConfig& flags) {
           chipClock=COLOR_NTSC*4.0;
           break;
       }
+      CHECK_CUSTOM_CLOCK;
       rate=chipClock/288;
       chipRateBase=rate;
       break;
@@ -1730,6 +1732,7 @@ void DivPlatformOPL::setFlags(const DivConfig& flags) {
           chipClock=COLOR_NTSC*8.0;
           break;
       }
+      CHECK_CUSTOM_CLOCK;
       rate=chipClock/768;
       chipRateBase=chipClock/684;
       break;
diff --git a/src/engine/platform/opll.cpp b/src/engine/platform/opll.cpp
index a8b51b10..77dea2e7 100644
--- a/src/engine/platform/opll.cpp
+++ b/src/engine/platform/opll.cpp
@@ -958,6 +958,7 @@ void DivPlatformOPLL::setFlags(const DivConfig& flags) {
   } else {
     chipClock=COLOR_NTSC;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/36;
   patchSet=flags.getInt("patchSet",0);
   for (int i=0; i<11; i++) {
diff --git a/src/engine/platform/pce.cpp b/src/engine/platform/pce.cpp
index e8a308f1..f6a8df51 100644
--- a/src/engine/platform/pce.cpp
+++ b/src/engine/platform/pce.cpp
@@ -565,6 +565,7 @@ void DivPlatformPCE::setFlags(const DivConfig& flags) {
   } else {
     chipClock=COLOR_NTSC;
   }
+  CHECK_CUSTOM_CLOCK;
   antiClickEnabled=!flags.getBool("noAntiClick",false);
   rate=chipClock/12;
   for (int i=0; i<6; i++) {
diff --git a/src/engine/platform/pcspkr.cpp b/src/engine/platform/pcspkr.cpp
index 226ee98c..59154dca 100644
--- a/src/engine/platform/pcspkr.cpp
+++ b/src/engine/platform/pcspkr.cpp
@@ -598,6 +598,7 @@ void DivPlatformPCSpeaker::setFlags(const DivConfig& flags) {
       chipClock=COLOR_NTSC/3.0;
       break;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/PCSPKR_DIVIDER;
   speakerType=flags.getInt("speakerType",0)&3;
   oscBuf->rate=rate;
diff --git a/src/engine/platform/pet.cpp b/src/engine/platform/pet.cpp
index 8a606ecf..3722d52f 100644
--- a/src/engine/platform/pet.cpp
+++ b/src/engine/platform/pet.cpp
@@ -300,6 +300,7 @@ int DivPlatformPET::init(DivEngine* p, int channels, int sugRate, const DivConfi
   dumpWrites=false;
   skipRegisterWrites=false;
   chipClock=1000000;
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/SAMP_DIVIDER; // = 250000kHz
   isMuted=false;
   oscBuf=new DivDispatchOscBuffer;
diff --git a/src/engine/platform/pong.cpp b/src/engine/platform/pong.cpp
index 1015fdda..a98fe7ba 100644
--- a/src/engine/platform/pong.cpp
+++ b/src/engine/platform/pong.cpp
@@ -21,7 +21,7 @@
 #include "../engine.h"
 #include "../../ta-log.h"
 
-#define CHIP_DIVIDER 16
+#define CHIP_DIVIDER 1024
 
 void DivPlatformPong::acquire(short* bufL, short* bufR, size_t start, size_t len) {
   int out=0;
@@ -226,8 +226,9 @@ bool DivPlatformPong::keyOffAffectsArp(int ch) {
 }
 
 void DivPlatformPong::setFlags(const DivConfig& flags) {
-  chipClock=15625;
-  rate=chipClock;
+  chipClock=1000000;
+  CHECK_CUSTOM_CLOCK;
+  rate=chipClock/64;
   oscBuf->rate=rate;
 }
 
diff --git a/src/engine/platform/rf5c68.cpp b/src/engine/platform/rf5c68.cpp
index e33cfbf3..f13a25aa 100644
--- a/src/engine/platform/rf5c68.cpp
+++ b/src/engine/platform/rf5c68.cpp
@@ -348,6 +348,7 @@ void DivPlatformRF5C68::setFlags(const DivConfig& flags) {
     case 2: chipClock=12500000; break;
     default: chipClock=8000000; break;
   }
+  CHECK_CUSTOM_CLOCK;
   chipType=flags.getInt("chipType",0);
   rate=chipClock/384;
   for (int i=0; i<8; i++) {
diff --git a/src/engine/platform/saa.cpp b/src/engine/platform/saa.cpp
index 7f48bca4..c3e48f1f 100644
--- a/src/engine/platform/saa.cpp
+++ b/src/engine/platform/saa.cpp
@@ -438,6 +438,7 @@ void DivPlatformSAA1099::setFlags(const DivConfig& flags) {
   } else {
     chipClock=8000000;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/32;
 
   for (int i=0; i<6; i++) {
diff --git a/src/engine/platform/scc.cpp b/src/engine/platform/scc.cpp
index a8fbcd7c..a75496d5 100644
--- a/src/engine/platform/scc.cpp
+++ b/src/engine/platform/scc.cpp
@@ -375,6 +375,7 @@ void DivPlatformSCC::setFlags(const DivConfig& flags) {
       chipClock=COLOR_NTSC/2.0;
       break;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/8;
   for (int i=0; i<5; i++) {
     oscBuf[i]->rate=rate;
diff --git a/src/engine/platform/segapcm.cpp b/src/engine/platform/segapcm.cpp
index 860f9926..25de3395 100644
--- a/src/engine/platform/segapcm.cpp
+++ b/src/engine/platform/segapcm.cpp
@@ -486,7 +486,8 @@ void DivPlatformSegaPCM::reset() {
 
 void DivPlatformSegaPCM::setFlags(const DivConfig& flags) {
   chipClock=8000000.0;
-  rate=31250;
+  CHECK_CUSTOM_CLOCK;
+  rate=chipClock/256;
   for (int i=0; i<16; i++) {
     oscBuf[i]->rate=rate;
   }
diff --git a/src/engine/platform/sms.cpp b/src/engine/platform/sms.cpp
index 9f65a953..0ce4c836 100644
--- a/src/engine/platform/sms.cpp
+++ b/src/engine/platform/sms.cpp
@@ -568,6 +568,7 @@ void DivPlatformSMS::setFlags(const DivConfig& flags) {
       stereo=false;
       break;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/divider;
   for (int i=0; i<4; i++) {
     oscBuf[i]->rate=rate;
diff --git a/src/engine/platform/su.cpp b/src/engine/platform/su.cpp
index 931225b4..d85a9d94 100644
--- a/src/engine/platform/su.cpp
+++ b/src/engine/platform/su.cpp
@@ -511,6 +511,7 @@ void DivPlatformSoundUnit::setFlags(const DivConfig& flags) {
   } else {
     chipClock=1236000;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/4;
   for (int i=0; i<8; i++) {
     oscBuf[i]->rate=rate;
diff --git a/src/engine/platform/swan.cpp b/src/engine/platform/swan.cpp
index 222af4a5..852450a7 100644
--- a/src/engine/platform/swan.cpp
+++ b/src/engine/platform/swan.cpp
@@ -514,6 +514,7 @@ int DivPlatformSwan::init(DivEngine* p, int channels, int sugRate, const DivConf
   dumpWrites=false;
   skipRegisterWrites=false;
   chipClock=3072000;
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/16; // = 192000kHz, should be enough
   for (int i=0; i<4; i++) {
     isMuted[i]=false;
diff --git a/src/engine/platform/t6w28.cpp b/src/engine/platform/t6w28.cpp
index c6317e11..0d294836 100644
--- a/src/engine/platform/t6w28.cpp
+++ b/src/engine/platform/t6w28.cpp
@@ -343,6 +343,7 @@ void DivPlatformT6W28::notifyInsDeletion(void* ins) {
 
 void DivPlatformT6W28::setFlags(const DivConfig& flags) {
   chipClock=3072000.0;
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/16;
   for (int i=0; i<4; i++) {
     oscBuf[i]->rate=rate;
diff --git a/src/engine/platform/tia.cpp b/src/engine/platform/tia.cpp
index d4703e28..2a28cb0a 100644
--- a/src/engine/platform/tia.cpp
+++ b/src/engine/platform/tia.cpp
@@ -356,6 +356,7 @@ void DivPlatformTIA::setFlags(const DivConfig& flags) {
   } else {
     rate=COLOR_NTSC;
   }
+  CHECK_CUSTOM_CLOCK;
   chipClock=rate;
   mixingType=flags.getInt("mixingType",0)&3;
   for (int i=0; i<2; i++) {
diff --git a/src/engine/platform/vb.cpp b/src/engine/platform/vb.cpp
index a8baab3c..1523a153 100644
--- a/src/engine/platform/vb.cpp
+++ b/src/engine/platform/vb.cpp
@@ -486,6 +486,7 @@ void DivPlatformVB::notifyInsDeletion(void* ins) {
 
 void DivPlatformVB::setFlags(const DivConfig& flags) {
   chipClock=5000000.0;
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/16;
   for (int i=0; i<6; i++) {
     oscBuf[i]->rate=rate;
diff --git a/src/engine/platform/vera.cpp b/src/engine/platform/vera.cpp
index 2966f9d1..9294a344 100644
--- a/src/engine/platform/vera.cpp
+++ b/src/engine/platform/vera.cpp
@@ -438,6 +438,7 @@ int DivPlatformVERA::init(DivEngine* p, int channels, int sugRate, const DivConf
   dumpWrites=false;
   skipRegisterWrites=false;
   chipClock=25000000;
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/512;
   for (int i=0; i<17; i++) {
     oscBuf[i]->rate=rate;
diff --git a/src/engine/platform/vic20.cpp b/src/engine/platform/vic20.cpp
index d6200a16..52a08836 100644
--- a/src/engine/platform/vic20.cpp
+++ b/src/engine/platform/vic20.cpp
@@ -307,6 +307,7 @@ void DivPlatformVIC20::setFlags(const DivConfig& flags) {
   } else {
     chipClock=COLOR_NTSC*2.0/7.0;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/4;
   for (int i=0; i<4; i++) {
     oscBuf[i]->rate=rate;
diff --git a/src/engine/platform/vrc6.cpp b/src/engine/platform/vrc6.cpp
index 52a9350c..56df0e83 100644
--- a/src/engine/platform/vrc6.cpp
+++ b/src/engine/platform/vrc6.cpp
@@ -482,13 +482,14 @@ bool DivPlatformVRC6::keyOffAffectsArp(int ch) {
 void DivPlatformVRC6::setFlags(const DivConfig& flags) {
   int clockSel=flags.getInt("clockSel",0);
   if (clockSel==2) { // Dendy
-    rate=COLOR_PAL*2.0/5.0;
+    chipClock=COLOR_PAL*2.0/5.0;
   } else if (clockSel==1) { // PAL
-    rate=COLOR_PAL*3.0/8.0;
+    chipClock=COLOR_PAL*3.0/8.0;
   } else { // NTSC
-    rate=COLOR_NTSC/2.0;
+    chipClock=COLOR_NTSC/2.0;
   }
-  chipClock=rate;
+  CHECK_CUSTOM_CLOCK;
+  rate=chipClock;
   for (int i=0; i<3; i++) {
     oscBuf[i]->rate=rate/32;
   }
diff --git a/src/engine/platform/x1_010.cpp b/src/engine/platform/x1_010.cpp
index 683b36a6..b7382c28 100644
--- a/src/engine/platform/x1_010.cpp
+++ b/src/engine/platform/x1_010.cpp
@@ -922,6 +922,7 @@ void DivPlatformX1_010::setFlags(const DivConfig& flags) {
       chipClock=16000000;
       break;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/512;
   stereo=flags.getBool("stereo",false);
   for (int i=0; i<16; i++) {
diff --git a/src/engine/platform/ym2203.cpp b/src/engine/platform/ym2203.cpp
index b3dc596c..3d6eaa8a 100644
--- a/src/engine/platform/ym2203.cpp
+++ b/src/engine/platform/ym2203.cpp
@@ -952,6 +952,7 @@ void DivPlatformYM2203::setFlags(const DivConfig& flags) {
       ayDiv=16;
       break;
   }
+  CHECK_CUSTOM_CLOCK;
   noExtMacros=flags.getBool("noExtMacros",false);
   rate=fm->sample_rate(chipClock);
   for (int i=0; i<6; i++) {
diff --git a/src/engine/platform/ym2608.cpp b/src/engine/platform/ym2608.cpp
index 63c84ad5..e15bf6b4 100644
--- a/src/engine/platform/ym2608.cpp
+++ b/src/engine/platform/ym2608.cpp
@@ -1407,6 +1407,7 @@ void DivPlatformYM2608::setFlags(const DivConfig& flags) {
       ayDiv=32;
       break;
   }
+  CHECK_CUSTOM_CLOCK;
   noExtMacros=flags.getBool("noExtMacros",false);
   rate=fm->sample_rate(chipClock);
   for (int i=0; i<16; i++) {
diff --git a/src/engine/platform/ym2610shared.h b/src/engine/platform/ym2610shared.h
index 065eb5f3..c2dce8aa 100644
--- a/src/engine/platform/ym2610shared.h
+++ b/src/engine/platform/ym2610shared.h
@@ -294,6 +294,7 @@ template<int ChanNum> class DivPlatformYM2610Base: public DivPlatformOPN {
           chipClock=8000000.0;
           break;
       }
+      CHECK_CUSTOM_CLOCK;
       noExtMacros=flags.getBool("noExtMacros",false);
       rate=chipClock/16;
       for (int i=0; i<ChanNum; i++) {
diff --git a/src/engine/platform/ymz280b.cpp b/src/engine/platform/ymz280b.cpp
index 8a903ef0..28d50acf 100644
--- a/src/engine/platform/ymz280b.cpp
+++ b/src/engine/platform/ymz280b.cpp
@@ -494,6 +494,7 @@ void DivPlatformYMZ280B::setFlags(const DivConfig& flags) {
           chipClock=16934400;
           break;
       }
+      CHECK_CUSTOM_CLOCK;
       rate=chipClock/384;
       break;
     case 759:
diff --git a/src/engine/platform/zxbeeper.cpp b/src/engine/platform/zxbeeper.cpp
index 76af5022..7f3dfedf 100644
--- a/src/engine/platform/zxbeeper.cpp
+++ b/src/engine/platform/zxbeeper.cpp
@@ -293,6 +293,7 @@ void DivPlatformZXBeeper::setFlags(const DivConfig& flags) {
   } else {
     chipClock=COLOR_NTSC;
   }
+  CHECK_CUSTOM_CLOCK;
   rate=chipClock/4;
   for (int i=0; i<6; i++) {
     oscBuf[i]->rate=rate;
diff --git a/src/gui/sysConf.cpp b/src/gui/sysConf.cpp
index 326c39a9..170e2d8b 100644
--- a/src/gui/sysConf.cpp
+++ b/src/gui/sysConf.cpp
@@ -24,6 +24,7 @@
 bool FurnaceGUI::drawSysConf(int chan, DivSystem type, DivConfig& flags, bool modifyOnChange) {
   bool altered=false;
   bool restart=settings.restartOnFlagChange && modifyOnChange;
+  bool supportsCustomRate=true;
 
   switch (type) {
     case DIV_SYSTEM_YM2612:
@@ -765,6 +766,8 @@ bool FurnaceGUI::drawSysConf(int chan, DivSystem type, DivConfig& flags, bool mo
           flags.set("echoFeedback",echoFeedback);
         });
       }
+
+      supportsCustomRate=false;
       break;
     }
     case DIV_SYSTEM_X1_010: {
@@ -1401,6 +1404,8 @@ bool FurnaceGUI::drawSysConf(int chan, DivSystem type, DivConfig& flags, bool mo
         });
       }
 
+      supportsCustomRate=false;
+
       break;
     }
     case DIV_SYSTEM_MSM5232: {
@@ -1542,13 +1547,15 @@ bool FurnaceGUI::drawSysConf(int chan, DivSystem type, DivConfig& flags, bool mo
       break;
     }
     case DIV_SYSTEM_SWAN:
-    case DIV_SYSTEM_VERA:
     case DIV_SYSTEM_BUBSYS_WSG:
-    case DIV_SYSTEM_YMU759:
     case DIV_SYSTEM_PET:
     case DIV_SYSTEM_VBOY:
       ImGui::Text("nothing to configure");
       break;
+    case DIV_SYSTEM_VERA:
+    case DIV_SYSTEM_YMU759:
+      supportsCustomRate=false;
+      break;
     default: {
       bool sysPal=flags.getInt("clockSel",0);
 
@@ -1565,6 +1572,32 @@ bool FurnaceGUI::drawSysConf(int chan, DivSystem type, DivConfig& flags, bool mo
     }
   }
 
+  if (supportsCustomRate) {
+    ImGui::Separator();
+    int customClock=flags.getInt("customClock",0);
+    bool usingCustomClock=customClock>=100000;
+
+    if (ImGui::Checkbox("Custom clock rate",&usingCustomClock)) {
+      if (usingCustomClock) {
+        customClock=1000000;
+      } else {
+        customClock=0;
+      }
+      altered=true;
+    }
+    if (ImGui::InputInt("Hz",&customClock)) {
+      if (customClock<100000) customClock=0;
+      if (customClock>20000000) customClock=20000000;
+      altered=true;
+    }
+
+    if (altered) {
+      e->lockSave([&]() {
+        flags.set("customClock",customClock);
+      });
+    }
+  }
+
   if (altered) {
     if (chan>=0) {
       e->updateSysFlags(chan,restart);