diff --git a/src/mame/drivers/taitogn.c b/src/mame/drivers/taitogn.c
index 3d5cbffd562..f46505472ef 100644
--- a/src/mame/drivers/taitogn.c
+++ b/src/mame/drivers/taitogn.c
@@ -692,9 +692,9 @@ static MACHINE_CONFIG_START( coh3002t, taitogn_state )
 	/* sound hardware */
 	MCFG_SPEAKER_STANDARD_STEREO("lspeaker", "rspeaker")
 
-	MCFG_SPU_ADD( "spu", XTAL_67_7376MHz/2 )
-	MCFG_SOUND_ROUTE(0, "lspeaker", 0.35)
-	MCFG_SOUND_ROUTE(1, "rspeaker", 0.35)
+	MCFG_SPU_ADD("spu", XTAL_67_7376MHz/2)
+	MCFG_SOUND_ROUTE(0, "lspeaker", 0.45)
+	MCFG_SOUND_ROUTE(1, "rspeaker", 0.45)
 
 	MCFG_FRAGMENT_ADD( taito_zoom_sound )
 	MCFG_CPU_MODIFY("mn10200")
diff --git a/src/mame/drivers/zn.c b/src/mame/drivers/zn.c
index 822e0e9490d..e41ed938741 100644
--- a/src/mame/drivers/zn.c
+++ b/src/mame/drivers/zn.c
@@ -1207,6 +1207,8 @@ MACHINE_RESET_MEMBER(zn_state,coh1000tb)
 }
 
 static MACHINE_CONFIG_DERIVED(coh1000tb, zn1_1mb_vram)
+
+	/* basic machine hardware */
 	MCFG_CPU_MODIFY("maincpu")
 	MCFG_CPU_PROGRAM_MAP(coh1000tb_map)
 
@@ -1215,10 +1217,18 @@ static MACHINE_CONFIG_DERIVED(coh1000tb, zn1_1mb_vram)
 
 	MCFG_MB3773_ADD("mb3773")
 
+	/* sound hardware */
+	MCFG_SOUND_MODIFY("spu")
+	MCFG_SOUND_ROUTES_RESET()
+	MCFG_SOUND_ROUTE(0, "lspeaker", 0.45)
+	MCFG_SOUND_ROUTE(1, "rspeaker", 0.45)
+
 	MCFG_FRAGMENT_ADD(taito_zoom_sound)
 MACHINE_CONFIG_END
 
 static MACHINE_CONFIG_DERIVED(coh1002tb, zn1_2mb_vram)
+
+	/* basic machine hardware */
 	MCFG_CPU_MODIFY("maincpu")
 	MCFG_CPU_PROGRAM_MAP(coh1000tb_map)
 
@@ -1227,6 +1237,12 @@ static MACHINE_CONFIG_DERIVED(coh1002tb, zn1_2mb_vram)
 
 	MCFG_MB3773_ADD("mb3773")
 
+	/* sound hardware */
+	MCFG_SOUND_MODIFY("spu")
+	MCFG_SOUND_ROUTES_RESET()
+	MCFG_SOUND_ROUTE(0, "lspeaker", 0.45)
+	MCFG_SOUND_ROUTE(1, "rspeaker", 0.45)
+
 	MCFG_FRAGMENT_ADD(taito_zoom_sound)
 MACHINE_CONFIG_END