# Line in recording on computer - how to stop the hum **URL:** \ **Category:** Factual Questions\ **Created:** [June 26, 2004, 5:43pm UTC](https://boards.straightdope.com/t/line-in-recording-on-computer-how-to-stop-the-hum/252331 "2004-06-26T17:43:36Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [June 26, 2004, 5:43pm UTC](https://boards.straightdope.com/t/line-in-recording-on-computer-how-to-stop-the-hum/252331/1 "2004-06-26T17:43:36Z")
I finally got around to connecting my stereo system to my new computer. I run cables from the REC OUT on the receiver to the LINE IN of the computer. I’ve noticed that when there’s no sound going through, there is a loud hum. Actually, the hum is there when there is sound, but it is usually drowned out by the sound. Since the receiver is about six feet from the back of the computer, I have to use in-line connecters to make the connection. At first, I thought this might be the problem, but when I connected a Walkman to the same connectors, there is no hum. All components are plugged into properly grounded outlets. What do I need to do to stop this? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [June 26, 2004, 5:52pm UTC](https://boards.straightdope.com/t/line-in-recording-on-computer-how-to-stop-the-hum/252331/2 "2004-06-26T17:52:27Z")
Sounds a lot like a ground loop problem. You can break the loop with a 1:1 ground loop isolation transformer, like [url=http://www.beststuff.co.uk/xitel\_ground\_loop\_isolator.htmthis one. This is a UK site, just to show you what you’re looking for. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [June 26, 2004, 5:53pm UTC](https://boards.straightdope.com/t/line-in-recording-on-computer-how-to-stop-the-hum/252331/3 "2004-06-26T17:53:45Z")
Oops. [Fixed link](http://www.beststuff.co.uk/xitel_ground_loop_isolator.htm). ---
**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\ **Post date:** [June 26, 2004, 5:56pm UTC](https://boards.straightdope.com/t/line-in-recording-on-computer-how-to-stop-the-hum/252331/4 "2004-06-26T17:56:22Z")
You might have to live with this hum ☹ Anyway, here’s something you can do. Open the sound control panel and turn anything unused to ‘Mute’. SW synth, Line In, CD-Rom, whatever. ---
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [June 26, 2004, 5:56pm UTC](https://boards.straightdope.com/t/line-in-recording-on-computer-how-to-stop-the-hum/252331/5 "2004-06-26T17:56:55Z")
I’ll give that a try. Radio Shack carries them (big surprise :)) for $16. Thanks. ---
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [June 26, 2004, 5:58pm UTC](https://boards.straightdope.com/t/line-in-recording-on-computer-how-to-stop-the-hum/252331/6 "2004-06-26T17:58:05Z")
> [@Dog80](#): > > You might have to live with this hum ☹ > > Anyway, here’s something you can do. Open the sound control panel and turn anything unused to ‘Mute’. SW synth, Line In, CD-Rom, whatever. I tried this, but it didn’t help. Thanks, though. ---
**Author:** ![Gut](https://avatars.discourse-cdn.com/v4/letter/g/8dc957/32.png) [@Gut](https://boards.straightdope.com/u/Gut)\ **Post date:** [June 26, 2004, 7:08pm UTC](https://boards.straightdope.com/t/line-in-recording-on-computer-how-to-stop-the-hum/252331/7 "2004-06-26T19:08:27Z")
Is your television also connected to your stereo? In my case the ground loop was caused by the cable. Cable connected to vcr, vcr connected to stereo. When I connected my computer to the stereo it caused the ground loop hum. I solved it with this [dohicky thingy](http://www.siber-sonic.com/broadcast/GLoopFix.html). It’s the last picture on the page. To test if this is what’s causing the problem unplug your cable from your vcr/tv. If you don’t have your cable connected in the way I’ve described then I’m sorry I wasted your time and board bandwidth. ---
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [June 26, 2004, 8:26pm UTC](https://boards.straightdope.com/t/line-in-recording-on-computer-how-to-stop-the-hum/252331/8 "2004-06-26T20:26:43Z")
**Gut** , my satelite dish is connected to the stereo, but not with coaxial cables. I’ve been usuing heavy duty RCA cables (but not the ridiculously expensive type). ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [June 26, 2004, 8:34pm UTC](https://boards.straightdope.com/t/line-in-recording-on-computer-how-to-stop-the-hum/252331/9 "2004-06-26T20:34:12Z")
> [@Mr. Blue Sky](#): > > **Gut** , my satelite dish is connected to the stereo, but not with coaxial cables. I’ve been usuing heavy duty RCA cables (but not the ridiculously expensive type). RCA cables _are_ a type of coaxial cable. In any case, all common ground connections have the potential to contribute to ground loop effects, whether or not they are coaxial. You can try to isolate the source of the problem by starting with a single pair of devices and one connection between them (like your stereo and computer), then add connections and components until the problem appears.