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    Composer, Music Producer, Location Audio Recording
  • Interested in Sound for Picture

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  1. This place certainly lives up to its reputation. Thank you for the interesting lesson about forests and Germans.
  2. Constantin: This place has a well earned rep for folks attempting to be aggressive with new posters. Since I don't feel like a newbie after doing this for 30-35 years, I found Philip's tone a too smug. I thought his original answers sounded like he had not read my post and was just trying to be the 7,000 post boss. To speak to your post, I'm not really asking for help. I'm asking if anyone can say specifically what this interference might be. So far, in my opinion, the only answers that are starting to get there have to do with motion detectors. Philip suggested it might be a bad cable. That's could be a possibility, too. I didn't have time to move the mic around, but did move the cable two or three times, and couldn't really tell under the circumstance whether it was making a difference or not. I think suggestions like bad clocking, bad preamp, bad mic capsule are pretty thin possibilities due to the facts that I use the rig all the time and it's this venue that offers the interference. I think the frequency bands and the consistency are the big clues, and was hoping someone in this oh so knowledgeable group would simply be able to say what it is and they see it all the time. The "fix" is easy enough with RX-5. So thanks all for any other ideas you may have and for your charming welcome to this group.
  3. Perhaps... On just one mic? The interference was on one of the KM184 pair, both of which were up 15' or so in the air. The lights were quite a bit higher. The interference was continuous in terms of frequency content and amplitude for two hours. Level of the interference was very low compared to any acoustic sound the artists were making. All the mic lines were balanced XLR cables in good shape. So common mode rejection should keep everything quiet, but one mic was getting something from somewhere. I use this rig all the time, and the signature of the noise is pretty odd. I guess it could be the rig, but the issue seems to link to this venue. Definitely not an acoustic sort of overtone series. Ruler level at each frequency and in terms of amplitude. The amplitude modulation that can be seen in the diagrams and heard sounds a little like high speed Morris. Fast, but not so fast that one is not able to determine the tiny pauses occasionally between the frequency bursts, which are predominantly continuous. C'mon. This seems like the sort of thing that someone should recognize. The odd clues are the overtone relationships to the fundamental, and the continuous nature to the contamination. It's some sort of radio... Wireless mic? It's a church, and if there is a wireless system, it ain't mine, nor something I've encountered before.
  4. Yes. I guess you're right. This was a concert recording... a 40 voice choir. Did you read that there were seven other mics on the same stage that didn't "hear" the interference that was recorded on one track only? The venue was an old church. The stage (altar) was built in the last 50 years, and my suspicion is, may have some ethernet or some other leaky, in terms of electromagnetic radiation, wiring going on under the stage. I don't want to seem overly aggressive in my question to you, but if you look at the screenshots, this should probably suggest something other than the trees you are barking up... I think it's safe to assume there are not "many possible sources for noise like this". I think it's some sort of induced contamination. Anyone else?
  5. Can anyone give me some information as to what this sort of interference might be? (Attached are two screenshots from a brief iZotope RX-5 sample of a session I recorded last night. One shows the interference as a somewhat continuous (there is some amplitude modulation) frequency at 1kHz, with overtones at 2, 3, and 4 kHz. There are additional harmonics that get quieter as the frequency goes up and so are difficult to see on this example. The second screenshot is the same sample, using a feature of RX-5 that allows one to select the fundamental frequency, and then select for the overtones too. Here , it is easy to see additional harmonics at 5, 6, 7, 8, 9, and 10kHz. The frequencies are very specific. A little background, the rig is an Apogee Ensemble Thunderbolt into a MacBook Pro into ProTools. I was running eight channels of audio, using a Neumann KM-184 pair and AKG C414 pair and C451 pair condenser mics, a Sennheiser M-88, and an Electrovoice RE-20. Mics and cables were all on a medium size stage. The mic and cable that were bringing the interference to the recorder was off on the left side of the stage, 5-10 feet from other cables. I use the rig all the time without seeing this sort of interference. On Friday, I used the rig in one location, and Saturday in another (same everything; mics, cables, etc.). There was no interference on Friday and on Saturday, it there was. I also believe I have seen the interference at the same venue in the past. iZotope RX-5 fixes the issue without killing a lot of time, and in this situation, the result is unnoticeable. My question is; what does this look like to you?
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