diff --git a/src/mame/drivers/playmark.c b/src/mame/drivers/playmark.c
index a8b99dda33e..029682a46e7 100644
--- a/src/mame/drivers/playmark.c
+++ b/src/mame/drivers/playmark.c
@@ -1144,11 +1144,11 @@ MACHINE_CONFIG_END
 static MACHINE_CONFIG_START( excelsr, playmark_state )
 
 	/* basic machine hardware */
-	MCFG_CPU_ADD("maincpu", M68000, 12000000)   /* 12 MHz */
+	MCFG_CPU_ADD("maincpu", M68000, XTAL_24MHz/2)   /* 12 MHz */
 	MCFG_CPU_PROGRAM_MAP(excelsr_main_map)
 	MCFG_CPU_VBLANK_INT_DRIVER("screen", playmark_state,  irq2_line_hold)
 
-	MCFG_CPU_ADD("audiocpu", PIC16C57, 12000000)    /* 3MHz */
+	MCFG_CPU_ADD("audiocpu", PIC16C57, XTAL_24MHz/2)    /* 12MHz with internal 4x divisor */
 	/* Program and Data Maps are internal to the MCU */
 	MCFG_CPU_IO_MAP(playmark_sound_io_map)
 
@@ -1171,7 +1171,7 @@ static MACHINE_CONFIG_START( excelsr, playmark_state )
 	/* sound hardware */
 	MCFG_SPEAKER_STANDARD_MONO("mono")
 
-	MCFG_OKIM6295_ADD("oki", 1000000, OKIM6295_PIN7_HIGH)
+	MCFG_OKIM6295_ADD("oki", XTAL_1MHz, OKIM6295_PIN7_HIGH) /* 1MHz resonator */
 	MCFG_SOUND_ROUTE(ALL_OUTPUTS, "mono", 1.0)
 MACHINE_CONFIG_END