diff --git a/src/mame/drivers/m63.c b/src/mame/drivers/m63.c
index 13c552bf94d..0e6f670fc0e 100644
--- a/src/mame/drivers/m63.c
+++ b/src/mame/drivers/m63.c
@@ -768,7 +768,7 @@ static MACHINE_DRIVER_START( m63 )
 	MDRV_SPEAKER_STANDARD_MONO("mono") /* ????? */
 
 	MDRV_SOUND_ADD("ay1", AY8910, XTAL_12MHz/8)
-	MDRV_SOUND_ROUTE(ALL_OUTPUTS, "mono", 0.20)
+	MDRV_SOUND_ROUTE(ALL_OUTPUTS, "mono", 0.25)
 
 	MDRV_SOUND_ADD("ay2", AY8910, XTAL_12MHz/8) /* ????? */
 	MDRV_SOUND_ROUTE(ALL_OUTPUTS, "mono", 1.00)