Hum bucker

[burstingfist]

Just curious if anyone has had to use a hum bucker to alleviete 60hz rolls on their projections? About a week ago I was doing a concert, and there was somewhat noticable roll in the output.

[elbows]

Havent used one myself but this site explains it pretty well...

http://www.21best.com/21_best/electronic/security/video/filters/for_sale_.html

[KillingFrenzy]

You might try looping an output of one of your devices into the input of another to see if that helps. Also, see if the physical location of devices matters. Shielding can be an issue.

If you have one cranky component that is causing the problem, then it might save you $150.

If you think a long cable is the problem... try attaching the long cable to different devices to see if the humbar is consistent across all of them. If it isn't, try fooling with the device that has "issues". If you have a distribution amp around it might help as well, since it might boost a weak signal enough to make it along a longer cable. You might be able to solve the problem before you spend $150 for something that "might" work.

[sleepytom]

we use gaton vdas with built in humbuckers quite alot - they have fixed problems often and are allmost essental when doing AV stuff as the combined video + audio ground loops can get very complex

[burstingfist]

Are Audio hum and Video hum synonomous? Or are they results of two different phenomena? At this one club, when I get an audio line from the sound guy, a hum is caused in the main speaker system. It is a fairly long line. The sound guy said it was because we were drawing power from two separate circuits, thus creating a ground loop.

[sleepytom]

yep the two are caused by the same problem - the best solution is to ensure that your power comes from the same phase as the sound (all power that is - including projectors) and to use "ground loop isolators" in the audio line - these are little boxes with a pair of phonos on each side that you run the audio signal through they make a physical break in the curcuit and thus remove the possibilty of any ground loop. You can get them quite cheaply from a car hifi shop or maplins.

if your just running a line in for audio reactive visuals you can remove a hum causing audio ground loop by disconnecting the screen of you audio line in at one end - the sound will still get through but there will be no ground loop

there is a good explination of ground loops here (http://www.epanorama.net/documents/groundloop/index.html)

[burstingfist]

we use gaton vdas with built in humbuckers quite alot - they have fixed problems often and are allmost essental when doing AV stuff as the combined video + audio ground loops can get very complex

What is a "gaton vdas"? I find that when all my stuff is setup in the studio, I get no hum, but when I go to a gig, I get a subtle slow scrolling effect.

[burstingfist]

I picked up one of those USD $40 Radio Shack distribution amplifiers and it totally removed the hum in the projection. Why would this be? Does the dist amp sort "redo" the signal?