If no bass is present, in what you are playing, the subwoofer may turn itself off. Also, I've owned subwoofers that will let you select "auto-off" or just "on-off" at your discretion. "on-off" will prevent it from turning off after certain time has elapsed. Check the switches on the back.
Subwoofer
Can anyone if possible answer why my subwoofer goes into stand by mode all the time after just a few minutes of playing if the song is base heavy its ok movies are better in paticular new films but i find myself always adjusting the gain up and down its a Sunfire True Subwoofer MK IV have mains center and rears set at 90 hz as the sub as well should i open the hz on the sub all the way but it gets to boomy i like tight tight bass at lowest db.I know this is a hard question to answer is it possible the sub itself is just getting old using old Sony ES 9000 for pre/pro. Thanx for the rookie question.😀.