May 5th, 2005

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Cinco de Mayo

Happy Cinco de Mayo! yarbiedoll and I plan to celebrate by going to a Mexican restaurant for supper tonight. Even my employer passed along Cinco de Mayo wishes, as an email with the following blurb landed in my inbox this morning:
Cinco de Mayo commemorates the Mexican army's defeat of the French at Puebla, Mexico, 100 miles east of Mexico City on May 5, 1862. The event has come to symbolize Mexican unity and patriotism.
What's not to celebrate on a holiday that commerates the defeat of the French? It reminds me of a favorite Google parody: French military victories (be sure to click the alternate suggestion).
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RFI Rant

I am currently being plagued by what I can only assume is RF interference. Over the weekend, I got some new equipment to record my Radio DTB podcasts and I've spent several hours over the past several nights trying to get a decent recording. Everything I've done has come out with an underlying regular and periodic "dit-dit-dit" background noise that I just can't get rid of. I can post-process the recording with software, which does a great job of eliminating the noise, but it makes my voice sound like a robot in a tunnel. Not exactly the effect I was going for.

I'm pretty close to my wit's end and would welcome any suggestions -- no matter how absurd or even repetitive -- from anyone who might have a clue about how to eliminate the interference. I know it's possible, 'cause I did record some good sample recordings with this exact equipment and set-up over the weekend. The big difference was that over the weekend, I was located in a fairly remote house on a river in a rural location, while now I'm located in a townhouse in a semi-urban location.

My setup: Microphone (MXL 990 Cardioid Condenser Mic) -> 3' mic cable -> mixer (Behringer Eurorack UB802 Mixer) -> tape-out cable (RCA -> stereo mini-jack) -> Griffin iMic -> USB -> Macintosh iBook SE (recording software: Audacity)

Downstairs, I wasn't terribly surprised to get the interference. The basement is a pit of potentially RF-emitting devices: everything related to my computer (printer, external hard drive, external cd burner, etc.), tv, stereo (and speakers), DVR, VCR, etc. I tried all sorts of settings on the knobs of my mixer and levels on Audacity. Listening to the signal through the headphones on the mixer, things sound fine. Listening to a recording, it sounds annoying.

I moved upstairs (3rd story) with only my mic, my mixer, my computer, and the necessary cables. I turned off my cell phone. I turned off the wireless card in my computer. I turned off the wireless router (located in the basement). I even turned off all the lights in the room (none of which was florescent). I pressed record, listened to the playback and heard the "dit-dit-dit-dit..." still there.

I'm going to try again, this time from the dining room and/or living room. Other than that I've run out of locations in my home. I'm really beginning to fear that there's RFI from my neighbors that's causing the problem. I hope that's not the case, 'cause I won't be able to do much about that. Otherwise, I might be able to find the offending source and eliminate or limit it.

Like I said, any suggestions are welcome. If anyone wants to hear samples of what I'm talking about (even if it's just out of curiosity), comment and I'll put some MP3s online later tonight or tomorrow.

[Update: More information about this problem and sample MP3s are included in another blog entry.]

[Update: More information: it's probably not the mixer.]
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More RFI

Well, I think I might agree with slitterst about the cause of the background noise on my new recording setup. I think it's my mixer (a Behringer Euroback UB802) causing RF interference.

Here are some sample MP3s:I also made a recording of my cheap lapel mic going through the mixer, but it had the same background noise as the nice mic had, and you could hardly hear my voice. I didn't feel like trying to get the levels right since it was obvious that it was having the same problem.

Another thing that made me think that the mixer is the problem is that the first time I tried to record with the cheap lapel mic going straight into the computer, I was getting the same interference. As soon as I unplugged the mixer, the interference went away. That's pretty damning evidence right there.

Well, I guess I'll still see about trying to make a recording with my new set-up in a more remote location again, just in case there still is a chance that I can make a decent recording with my new set-up, but I'm very pessimistic about the whole issue at this point, so I'll also be looking into how to return/replace the mixer.

The really disappointing thing about this whole situation is that I bought the UB802 on the recommendation of several other podcasters -- it's often described as "the podcaster's best friend" -- and also because it is specifically advertised as having a high resistance to RFI. *sigh* Maybe I just have a dud mixer and a replacement will take care of it. *crosses fingers*

And if I don't go with a straight-up replacement Behringer, I'm open to any suggestions for a replacement pre-amp, prefferably with the mixing capabilities that my Behringer has. And, yeah, in about the same price range.

[Update: More information: it's probably not the mixer.]