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Old July 14th, 2007, 04:12 PM   #31
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Tim,

We recorded on DV using an XL2. If the tapes were messed up, wouldn't it show up prominently in the video?
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Old July 14th, 2007, 06:17 PM   #32
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Depends what has contaminated the tapes, so to speak. It may not affect the video, don't know.

Since my last post I have done some more playing in the audio editor. If you filter out everything except 4K, then slow the track way down while maintaining the pitch, the sound starts to become familiar. It sounds like a modem communicating. Now at regular speed, it doesn't, it's much higher in speed and frequency. Sort of like what DSL high-speed sounds like. The office scene most likely would have had DSL present in the room ... did the bedroom? Remember, the DSL signal is present on the phone lines whether the computer is on or not. If you had microphone cables laying in proximity to telephone wires then they could have picked up the signal.

Anyway, that's all the guesses I have.

Been in the audio business a long time and we have a saying ...

If it don't work ... it's a cable.

After you have checked everything twice and it still don't work ... it's a cable.

And when you are sure that every cable and every connection is perfect and it still don't work ... it's a cable.

Best of Luck ...

Tim
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Old July 15th, 2007, 08:48 AM   #33
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We have cable at home, not DSL. I do not know which of the two the office had.

Yet your point brings me back to my cell phone hypothesis. That is a form of modem too. I just do not understand how it could affect the signal running through the XLR cables.
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Old July 15th, 2007, 11:02 AM   #34
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"Pin 1 Error"

Quote:
Originally Posted by Emre Safak View Post
... your point brings me back to my cell phone hypothesis. That is a form of modem too. I just do not understand how it could affect the signal running through the XLR cables.
The answer to this is a condition called "pin 1 error" that exists in some XLR audio equipment including microphones and mixers. It works like this. The device is ostensibly shielded from RF by its metal enclosure, but this protection is foiled by a bad wiring decision. Internally, the XLR cable shield (pin 1) lead runs from the device's connector to the "ground" area of the device's circuit board. In turn, the ground area of the circuit board is connected by a short lead to the outer metal housing. The erroneous thought is that this is equivalent to connecting the shield directly to the housing. Instead, the short internal lead becomes a little broadcast antenna inside the device for the RF signal picked up the cable shield. The proper way to terminate the XLR cable shield is at the external interface with the device's housing.

I don't know if your problem is cell phone interference, but if it is, that's almost certainly how it is getting in.

If you do a search on pin 1 error you'll find, as I recall, where the original discoverer of this condition uncovered it in some big name microphones.
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Last edited by David Ennis; July 15th, 2007 at 11:13 AM. Reason: clarity, typos
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Old July 15th, 2007, 11:27 AM   #35
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Originally Posted by Emre Safak View Post
... your point brings me back to my cell phone hypothesis ...
Forgive the second post, but the science teacher in me is forcing me to say that a hypotheses begs an experiment. If you don't want to tear into your equipment to inspect the wiring, I'd put a cell phone (or two or three) right next to an XLR cable and turn them on while listening with phones. If I got the noise, I'd try obvious stuff like disconnecting the mic, etc.
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Old July 15th, 2007, 11:29 AM   #36
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Fascinating... so that means my Audio Technicas are poorly shielded? I will have to try taking a bunch of cell phones and putting them next to my mics some time, to confirm the hypothesis, unless somebody has already tried.

edit: You beat me to it. Great minds think alike!
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Old July 15th, 2007, 11:49 AM   #37
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It may be cell phones and I'd certainly do the experiment but most of the time cell phone interference is intermittent. The phones 'call home' every few minutes to let the system know where they are but it's not continuous data traffic unless they're actively in use.
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Old July 15th, 2007, 11:55 AM   #38
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Only a good experiment could determine whether your AT's are poorly shielded.

I once queried AT as to whether my AT3031's might be wired with pin 1 error. Their reply was that they never had a complaint about pin 1 error, but didn't answer my question directly.

It would be good to use cell phones of different brands because of their differences. Here's a thread where cell phone interference was discussed, and where Sam Gates very politely enlighten me about pin 1 error: http://www.dvinfo.net/conf/showthrea...ight=pin+error
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Old July 15th, 2007, 12:52 PM   #39
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Quote:
Originally Posted by Jim Boda View Post
LOL! Upon further review with headphones on...the beeps sound more electronic and seem to move around in the stereo image. Unidentified Flying beeps.
The beeps seem to be flying because his recording is slightly out of phase. Left channel is ahead of Right channel. The beeps are in Stereo! In fact all the audio on the sample is out of phase. Are there two XLR runs?
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Old July 15th, 2007, 01:02 PM   #40
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There are two mics running into the same camera.
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Old July 15th, 2007, 02:33 PM   #41
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it is definately an electronic interference not mechanical sound.
there is a difference in the timing between the two channels too, I mean the two channels were affected with a phase delay but the sequence of the beep is not the same
you can check the attachment where the pulse can be clearly seen.
amplified by 18db and a low cut at ~200Hz showed this.
it was the second clip originaly posted.
Attached Thumbnails
What is this **** beeping?-beeps.jpg  
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Old July 15th, 2007, 03:18 PM   #42
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You are right. There is slight phase difference in the sample but the pulses are distinct in each channel.
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Old July 15th, 2007, 10:48 PM   #43
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That is a great tool Vasilis. What is that plug-in called? That bright line through the display is the horizontal sync from his monitor. But why different pulses in each channel. I am now thinking induction rather than RF. Crazy stuff.
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Old July 16th, 2007, 04:06 PM   #44
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Quote:
Originally Posted by Glenn Davidson View Post
That is a great tool Vasilis. What is that plug-in called? That bright line through the display is the horizontal sync from his monitor. But why different pulses in each channel. I am now thinking induction rather than RF. Crazy stuff.
this is adobe audition's default spectral frequency display (not plug-in).
I'm really confused about the source :-$
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Old July 16th, 2007, 04:38 PM   #45
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Cell phone or monitor, right? I'm banking on cell phone; the frequency of the beeping displays a randomness than does not agree with monitors.
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