Display Issue - Low frequency audio (bass note) affecting picture in House of Worship - AVS Forum
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Old 04-07-2014, 02:06 PM - Thread Starter
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A particular low frequency bass note is affecting the video display on a DLP projector. Any ideas, video cable, internal lamp ballast contacts, lamp contacts?
Anyone experience this? This is for a Church.
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Old 04-07-2014, 03:12 PM
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Vibrations?

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Old 04-07-2014, 03:12 PM
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I'm confused... have you identified that a specific note from a bass guitar , keyboard, kick drum, etc. is affecting the video from the projector? If so why can this not be handled with basic EQ from the mixing console or PA processing?

If on the other hand you have some unknown interference with the projector and you are asking for troubleshooting steps (cable, lamp ballast, etc.) I don't understand why you say it is a bass note causing the issue.

Can you try explaining a different way and perhaps be more specific on how the DLP projector is being affected?

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Old 04-07-2014, 03:32 PM
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God says stop making so damn much noise.. he can hear you, turn it down! He gave us good ears, done mess them up with all that noise! He says make a joyful noise not a loud noise! biggrin.gifeek.gifsmile.gif
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Old 04-07-2014, 03:38 PM - Thread Starter
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I'm sure it's a resonant noise issue at a particular frequency. I believe the audio system has an EQ, so I was going to run a frequency sweep to attempt to determine what frequency may be affected and bump that down on EQ. Another forum has mentioned a bad solder joint being affected by that frequency?
Just wondering if anyone has experienced this?
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Old 04-07-2014, 03:54 PM
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if it's a resonant frequency thing a sweep is a good way to handle it. Find it and then cut it out with the EQ.

I used to mix audio for a church and we could tell what frequency was causing trouble based on which HVAC vent in the room was vibrating... one of them was 35Hz, another was 50Hz, etc... but we found out that information just by running sweeps and playing with it. Done properly you would think the building was going to collapse on you. eek.gif Fun with the oscillator... biggrin.gif

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Old 04-07-2014, 04:32 PM
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This is what we plan to use in our church on two Christie DHD800 projectors:

http://hometoys.com/emagazine.php?url=/ezine/11.06/brent/index.htm

http://www.nigelbdesign.com/pdfs/Anti-Vibration%20Isolatin%20mount.pdf

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Old 04-07-2014, 06:41 PM
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Quote:
Originally Posted by walterappleby View Post

if it's a resonant frequency thing a sweep is a good way to handle it. Find it and then cut it out with the EQ.

I used to mix audio for a church and we could tell what frequency was causing trouble based on which HVAC vent in the room was vibrating... one of them was 35Hz, another was 50Hz, etc... but we found out that information just by running sweeps and playing with it. Done properly you would think the building was going to collapse on you. eek.gif Fun with the oscillator... biggrin.gif
If he has a mixing board/PA, he probably could install an app on his phone/tablet to accomplish the frequency generator task.

2014
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Old 04-08-2014, 08:30 AM
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Quote:
Originally Posted by 42Plasmaman View Post

If he has a mixing board/PA, he probably could install an app on his phone/tablet to accomplish the frequency generator task.

If he has a decent console it probably already has a tone generator/oscillator built in. Even without it a basic parametric EQ will be enough to find/fix it.

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Old 04-08-2014, 10:41 AM
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Any chance it's a ground loop?
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Old 04-10-2014, 05:18 AM
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Quote:
Originally Posted by enricoclaudio View Post

This is what we plan to use in our church on two Christie DHD800 projectors:

http://hometoys.com/emagazine.php?url=/ezine/11.06/brent/index.htm

http://www.nigelbdesign.com/pdfs/Anti-Vibration%20Isolatin%20mount.pdf

Like 20 grand a pop. Little steep for this forum.
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