# Subwoofer Question **URL:** \ **Category:** Factual Questions\ **Created:** [December 23, 2016, 10:15pm UTC](https://boards.straightdope.com/t/subwoofer-question/775485 "2016-12-23T22:15:27Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![SanDiegoTim](https://avatars.discourse-cdn.com/v4/letter/s/85e7bf/32.png) [@SanDiegoTim](https://boards.straightdope.com/u/SanDiegoTim)\ **Post date:** [December 23, 2016, 10:15pm UTC](https://boards.straightdope.com/t/subwoofer-question/775485/1 "2016-12-23T22:15:27Z")
I’ve got a Jamo 210 subwoofer. On the back there are three toggled settings: On, Off and Auto. While I understand “Off,” what’s the difference between “On” and “Auto”? ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [December 23, 2016, 10:26pm UTC](https://boards.straightdope.com/t/subwoofer-question/775485/2 "2016-12-23T22:26:03Z")
On means the amplifier is powered up all the time. Auto usually means that the power amplifier is powered down, and the input detects the presence of signal and turns it on. If there is no signal for a while the power amplifier turns off again. Saves power, but you may get a slightly annoying pause when you first start playing sound as it powers the amplifier up. (In order to protect the speaker driver it is usual to power up the amplifier, wait, and then connect the driver - so a second or so.) ---
**Author:** ![SanDiegoTim](https://avatars.discourse-cdn.com/v4/letter/s/85e7bf/32.png) [@SanDiegoTim](https://boards.straightdope.com/u/SanDiegoTim)\ **Post date:** [December 23, 2016, 11:04pm UTC](https://boards.straightdope.com/t/subwoofer-question/775485/3 "2016-12-23T23:04:12Z")
Thx