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Robots for Robots → General Hardware / Software Discussion → Room hum
Hello 
I did a recording in the studio on Friday with 21 people whispering. I used a Rode Classic II Valve mic, a Rode NT2-A and a Carillion ribbon mic. On all three, although not as badly on the Carillion (probably because it's not such a great microphone), I have a rather loud room hum. What's the best way to get rid of this? EQ or some kind of filter? Any help would be greatly appreciated. Thanks!
noise reduction and get hum as a sample
i think the problem you are encountering is a low output source (whisper) being miked from a distance (condsidering 21 people). basically there is not much difference in level between the background room noise and what you are recording. so when you turn up or add gain to the signal you bring up the noise too. get the people to whisper directly into the mic from a close distance. the greater the level between the source and background room noise the better. other than that you could book some time in a treated room.
If at all possible I'd use a shotgun mic on this (the kind with a cone, like in spy series) if you really, really must mic them all at the same time in the actual room. more practical would probably to simply close mic all of them, take a impulse-response of the room and a convolution reverb. I don't really know what "room hum" is but it sounds like most of this could be prevented by using a very dead room (a library might do?) or a space build for having acoustics that work with the human voice, at universities there should be plenty of lecture halls. I'd still use a shotgun mic there if one is available.
A noise reduction plugin might save the recording that you have, but it sounds like a very tricky case.
Hmm..well it's a studio it's as dead as they could make it Zachary. It isn't very big maybe 4 x 4m & they were quite close to the mics 1/2 m away? We still had hum the day before when we recorded dialogue with a pop shield. Unfortunately, getting the dancers for one afternoon was hard enough so I can't do another recording. Any more fixit ideas like bias gave? I use the latest version of Logic Pro.
what frequency range is the hum in? You can maybe just EQ it out, if it's just 50hz. It will be harder if you have harmonics and not really possible if it's got modulation happening, or worse - intermodulation with the actual recorded material...
Anyway - doesn't hurt to have a go... grab your basic software parametric EQ, set it for a narrow bandwitch (pretty high Q value, but not the highest) and max level boost, then slowly sweep it up and down, listening to what happens to the hum... this way you can easily see what sounds exist in your recording at any frequency cause they'll jump out as you go over them.... so find wherever the hum lives, and then surgically remove it.
Awesome thanks Julian! I didn't understand all of that (still leaning) but I'll give it a try tonight & ask you if I'm not sure of something
cool! I'm not planning on doing anything much tonight apart from working out what my new sequencers can and can't do, so give me a call and I can talk you through the process if you want.
Great thanks hon! I get free calls within Oz, do you have a landline you can send me? Otherwise I'll call you on your mobile. I just got home from work though so will make dinner etc first.
None of your lecturers knew how to fix it?
I only have one lecturer for sound and he only works 3 days a week Mon - Wed. I wanted to get this fixed over the weekend so when the choreographer comes into the studio with me on Mon to look at editing the recordings, the problem would be fixed.
i seeee
Well, I ran everything through the Denoiser and it seemed to fix it. Sorry I didn't call Julian, Logic wasn't working properly on my computer. I will call you soon to catch up though!
awesome news about the denoiser working so well - it sucks when you've recorded something you can't easily make again, and then find out later it didn't work out right.
the EQ thing was going to be more of an experiment/execrcise anyway. It could be fun to play with sometime when you have a spare moment and a working home setup. :-)
turn off your vibrator.... 
I don't need a vibrator Roger 
Robots for Robots → General Hardware / Software Discussion → Room hum
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