what the hell is this noise
- September 14th, 2013
- Posted in studio
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Let’s play everybody’s favourite new game, “what the hell is this noise?”!
It’s captured on a live mic in a quiet recording studio; the sound is not audible in the room itself. I’m really curious if it sounds familiar to anyone, and reminds them of anything other than ground loop:
This was picked up on AKG200 microphones, across multiple mics (All AKG200s) and cables, so it’s not am individual microphone or cable problem.
It starts at about 450hz and goes all the way through the floor. There’s something to amplify throughout that signal range. I put a sweep equaliser and found tones to boost throughout that range. Nothing above that, though.
I realise it sounds like a ground loop, but it’s not; I chased the 60hz question for a while, but it’s far wider than that. I have a workaround that reduces it to inaudibility that involves changing nothing connected to any of the equipment – at least, as long as I’m recording other people. That would not be true for a ground loop.
I posted about this a couple of places last night; the link goes to the Facebook link that got a bunch of comments.
Also, if I change out the mic to an Octava 012, it goes away. Also, a Shure SM57. No cable change fixes any part of it.
Whatcha got?
Interference from a central air/furnace? Or appliance? My new furnace makes weird noises on AM-the old one didn’t. So does the new fridge and washer, and I suspect it’s coming through the power line. In part,your mystery sounds like an erratic contact somewhere-sorta. Years ago, I hepled chase down some weird noises in a ancient vacuum tube PA system-turned out to be crosstalk from a nearby phone line-took a couple weeks to isolate it because everything was in the walls and almost impossible to get to.
For as long as I’ve owned my house, there’s been weird interference at around 650 Khz AM-I have no idea what it is, but it sounds like the interference an old CRT TV makes. There’s nothing nearby that would account for it.
Maybe it’s EVP and Jimmy Hoffa is trying to contact you…
It’s actually pretty stable as long as I don’t move. The changes are me moving around the microphone.
None of the appliances are new; the furnace hasn’t been turned on for the year yet, and it goes all day when it goes.
I have a copy of Hoffa’s authorised biography. Maybe he’s trying to get me to read it. THAT’S NOT EFFECTIVE COMMUNICATION, JIMMY!
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