diff --git a/src/mame/drivers/namcos12.cpp b/src/mame/drivers/namcos12.cpp
index c9aac3d4668..b0cdebf113c 100644
--- a/src/mame/drivers/namcos12.cpp
+++ b/src/mame/drivers/namcos12.cpp
@@ -1665,7 +1665,7 @@ static MACHINE_CONFIG_START( coh700, namcos12_state )
 
 	MCFG_PSX_DMA_CHANNEL_READ( "maincpu", 5, psx_dma_read_delegate( FUNC( namcos12_state::namcos12_rom_read ), (namcos12_state *) owner ) )
 
-	MCFG_CPU_ADD("sub", H83002, 16737350)
+	MCFG_CPU_ADD("sub", H83002, 16934400) // frequency based on research (superctr)
 	MCFG_CPU_PROGRAM_MAP(s12h8rwmap)
 	MCFG_CPU_IO_MAP(s12h8iomap)
 
@@ -1691,7 +1691,7 @@ static MACHINE_CONFIG_START( coh700, namcos12_state )
 	/* sound hardware */
 	MCFG_SPEAKER_STANDARD_STEREO("lspeaker", "rspeaker")
 
-	MCFG_C352_ADD("c352", 29168000, 332)
+	MCFG_C352_ADD("c352", 25401600, 288)
 	MCFG_SOUND_ROUTE(0, "rspeaker", 1.00)
 	MCFG_SOUND_ROUTE(1, "lspeaker", 1.00)
 	MCFG_SOUND_ROUTE(2, "rspeaker", 1.00)
diff --git a/src/mame/drivers/namcos23.cpp b/src/mame/drivers/namcos23.cpp
index 0d730716a07..9f353125ea5 100644
--- a/src/mame/drivers/namcos23.cpp
+++ b/src/mame/drivers/namcos23.cpp
@@ -1267,10 +1267,17 @@ Notes:
 #include "machine/namco_settings.h"
 
 #define JVSCLOCK    (XTAL_14_7456MHz)
-#define H8CLOCK     (16737350)      /* from 2061 */
-#define BUSCLOCK    (16737350*2)    /* 33MHz CPU bus clock / input */
-#define C352CLOCK   (25992000)  /* measured at 25.992MHz from 2061 pin 9  */
-#define C352DIV     (296)
+
+//#define H8CLOCK     (16737350)      /* from 2061 */
+//#define BUSCLOCK    (16737350*2)    /* 33MHz CPU bus clock / input */
+//#define C352CLOCK   (25401600)  /* previously measured at 25.992MHz from 2061 pin 9  */
+//#define C352DIV     (296)
+
+#define H8CLOCK     (16934400)      /* based on research (superctr) */
+#define BUSCLOCK    (16934400*2)
+#define C352CLOCK   (25401600)
+#define C352DIV     (288)
+
 #define VSYNC1      (59.8824)
 #define VSYNC2      (59.915)
 #define HSYNC       (16666150)