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kkissinger
Joined: Mar 28, 2006 Posts: 1354 Location: Kansas City, Mo USA
Audio files: 42
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Posted: Tue Jan 26, 2010 12:21 pm Post subject:
Advice needed for balanced cabling problem Subject description: How do I get rid of emf pops? |
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Perhaps someone can help me with a problem that crops up from time to time...
An engineer is attempting to record his church choir and the recordings contain pops whenever the organist presses and releases pedal notes.
The source of the problem is the pipe organ's electro-mechanical relays that induce emf into the organ cables. The mic cables, in turn, pick up the momentary magnetic fields.
I suggested that he experiment by running the cables along different paths and angles, to avoid coiling extra cable, and to make sure the shields are well-grounded.
I have dealt with this problem myself and it can be really difficult -- even with balanced lines (and likely impossible with unbalanced!).
Does anyone have suggestions or solutions? Thank you in advance for your help! _________________ -- Kevin
http://kevinkissinger.com |
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ark
Joined: Mar 06, 2008 Posts: 679 Location: New Jersey
Audio files: 13
G2 patch files: 31
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Posted: Tue Jan 26, 2010 1:14 pm Post subject:
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How about a digital snake?
For that matter, how about putting an outboard mic preamp near each microphone to raise the voltage and lower the impedance? |
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BobTheDog
Joined: Feb 28, 2005 Posts: 4044 Location: England
Audio files: 32
G2 patch files: 15
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Posted: Thu Jan 28, 2010 4:10 am Post subject:
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Wrap the organ in silver paper |
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kkissinger
Joined: Mar 28, 2006 Posts: 1354 Location: Kansas City, Mo USA
Audio files: 42
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Posted: Thu Jan 28, 2010 6:53 am Post subject:
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Thank you very much for the ideas. I'm going to take a look at the relay stack... a possible solution will be to connect spark-suppression diodes across the relays. I'm dropping by the church today to take a look. _________________ -- Kevin
http://kevinkissinger.com |
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kkissinger
Joined: Mar 28, 2006 Posts: 1354 Location: Kansas City, Mo USA
Audio files: 42
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Posted: Thu Feb 04, 2010 5:55 am Post subject:
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kkissinger wrote: | Thank you very much for the ideas. I'm going to take a look at the relay stack... a possible solution will be to connect spark-suppression diodes across the relays. I'm dropping by the church today to take a look. |
I dropped by the church and met with the organist and the sound engineer. I brought some diodes with me and determined that the solution will be to install diodes across each relay coil -- nearly 200 of them!
Will be kind of fun to install these -- I enjoy the smell of solder _________________ -- Kevin
http://kevinkissinger.com |
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EdisonRex
Site Admin
Joined: Mar 07, 2007 Posts: 4579 Location: London, UK
Audio files: 172
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Posted: Sun Feb 07, 2010 5:22 am Post subject:
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That's a particularly good solution as it will also help preserve the relays. You don't want to have to replace all those relays in 10 years! _________________ Garret: It's so retro.
EGM: What does retro mean to you?
Parker: Like, old and outdated.
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