Remove A/C Rumble?

Zilch


I did some recording in my office, and unfortunately I was unable to turn off the A/C.  It's fairly noisy and very noticeable, especially when the vocalist isn't singing. :(  (In retrospect my levels could have been better)

Any tips for cleaning it up?  (Without spending $1000s on plugins)

I've tried the Remove Silence settings, and it tends to clip the vocals badly.  Any hints on the settings (there are no example presets to guide you)

On a related note, I've noticed the following two bugs (?) for X1b:

1) Clicking the Audition button on the Remove Silence dialog box plays the clip back unprocessed
2) Audio engine dies at random when deleting clips while the transport is playing (was nuking bits that should have been silent)

Can anyone confirm these two?

That's a drag, Zilch - I've pulled out that particular part of your post because it sounds like you don't plan on doing a lot of editing.  There's no way you would want to keep a vocal track full on even when it's recorded under good conditions.  You must use a volume envelope surrounding the vocal like a glove, so that it opens up only in time to catch the first part of a note, and then drop out as soon as possible while still sounding natural.  Slicing and dicing the track is also in order, so that all the pauses are either cut out or dropped down to nothing with the envelope.

You'll still have the added noise to the vocal - something which nice plug-ins can take out, usually by analyzing a portion of the track with just the noise and then using that as a custom filter - but you don't want to spend bucks.  So you'll need to do some experimenting with EQ to find the frequencies which are predominant in the AC sound--and then notch those frequencies out of the vocal.  It will change the sound of the singer, but hopefully when blended with the backing tracks, you can salvage this to a good degree.

Randy B.

I'd just cut the track up manually to do the same thing as 'remove silence'. Just put a split in each of the gaps between the singing and then trim the clips back and forth so they start and finish around the blocks of words. Realtime fades on the clips are your friends here to get a nice smooth finish.

If it's low rumble in vox I think my next port of call would be to use an EQ with a HPF and just cut out all the lows (you should be able to roll it to about 70hz without too much detriment to the vocal. As Randy suggests, you could sweep a notch around if there's anything obvious further up the spectrum.

If the noise was still noticeable between the words I'm might consider putting a gate on there too, but I'd probably not have it completely killing the signal, rather just adding a bit of attenuation to the quiet sections.

Child

Maybe record the noise, use a spectral analyzer and cut the most pronounced freqs if they don't share too much in common with the vocals?

Zilch


I did some recording in my office, and unfortunately I was unable to turn off the A/C.  It's fairly noisy and very noticeable, especially when the vocalist isn't singing. :(  (In retrospect my levels could have been better)

Any tips for cleaning it up?  (Without spending $1000s on plugins)

If you want to send me the .wav files I can clean them up with Sound Forge's noise reduction plug.  PM me if you want and we can work out the details.
 
John

jbow

...This "Envelope" interests me. I assume that you mean editing everything out right up to where the vocals start and end, and editing out any noise in breaks but from the way you said it I am not sure...

Hi, Julien

Here, I made a quick screen shot for you in X1.  This is a volume envelope of the sort I was talking about.  It was hand drawn, which is the way to get the most accurate results.  Recording automation in real time works fine, but is likely to be less accurate with swoops up or down coming sooner or later than intended.  It's not always critical to have an envelope sooooo perfect, but I think for a vocal track it's best to get picky, and so hand-editing cleans things up.

I also talked about slicing out silence, and other people on the thread mentioned that.  I usually use a combination of the two approaches- cutting out bits, and making a volume envelope.  If there's a silence of some duration, a measure or more, I cut and throw out the silence.  But this example is showing the clip being left intact, with the volume envelope fitting "like a glove."  I've added arrows and text showing how I've dropped out room noise in-between words, I've swept up when part of a word needed to be louder, pushed some levels down that were too loud, and took out an unwanted breath.

That's all I meant - having a detailed volume envelope which can go a long ways to "compressing" the signal, helping the track maintain a more constant volume, before applying a compressor plug-in.



Randy B.

jbow


Wow... I will have to let this soak in a bit. This is very cool and something I will learn to do. Thank you for taking the time to explain. I have so much to learn.

Julien

Cool, Julien - Glad the screen shot and post were helpful.  I'm replying to reassure you that what I described and show in that shot is not difficult to do.  It's not even of "intermediate" difficulty.  A bit of text to help explain:

--In the track header of the audio track, use the filter menu to see automation.
--Choose Volume.
--A volume envelope will appear, set at the fader's current level.
--With the Smart Tool, start clicking on the line to add nodes.
--Drag the nodes to where you want them.
--Right click to change the default linear curves (speed of moving from one node to another) to either Slow or Fast.

That's all there is to it.  Just ask for a volume envelope to be created, then start experimenting with nodes.  Hands on experience will show you within minutes that's it easy to feel out once you try it.

Remember that recording automation moves in real time works fine in a lot of cases.  It's nice to go back over your automation and fine tune it with by-hand editing.  Or you can do an envelope completely by hand as per the above.

Really easy.  Try it.

Randy B.

The only thing about ducking the vocal in between words is that you might notice the AC hum going away and coming back which might sound worse. Unless of course there is so much going on in the mix that when the vocals are present the hum is masked.

Noise reduction is a much better way for sure and if the noise is constant it will do a brilliant job too. Then follow that with some precision editing in an editing program for final cleaning up and touching up.

Another option not mentioned yet might be to create a very steep notch filter right at that frequency. Digital plugins will allow you to do that. And it might just work a treat too. (Adobe Audition has got what they call Scientific filters. You can create a notch only a few Hz wide and it works!)

Another good reason for wearing headphones when in other locations and really listen hard for any unwanted sounds. I have been caught a few times too.

Mike is correct with this. Two shallow passes works much better than a deep pass. And you don't have to reduce the noise by 60 db either. I found even lowering it 10 or 12 db will effectively remove it but there will be fewer artifacts as a result of only asking for a -12 db drop in the hum. Its good to experiment with the Noise Reduction Level slider and the Reduce by amount.

You can edit the artifacts out as well, they often happen after a sound has finished.

Another trick is to set up that frequency curve so it only applies noise reduction in specific areas of the spectrum and hum is good because you can set it up to only act on a very small part of the spectrum and leave everything outside that alone hence artifacts are minimal or non existent.  The part of the waveform you take the noise print from is also quite critical. It will vary the results a lot too.

A very steep notch (a few Hz wide) such as the scientific filters in Audition will also do a great job of pulling out hum.

I have pulled out some terrifying background noise with Audition.  Once a conversation (interview) with aircon noise as loud as the dialogue. And all because some slack live sound recordist did not check his headphones for background sounds. Mike you would not let that happen would you? They could have turned off the aircon easily and the result would have been totally different. I got most of it out ( with Audition) and added in some nice room tone and were able to get away with it. But it took hours for me to do it. Hum is much better, the more uniform it is the easier it can take it out and all of it too. Another was a power generator out in the middle of Australia doing a scene for a film. They could have moved it 30 yards away and buried it in a hole (behind a shed) and it would have been nothing in comparison. I pulled most of it out too and dropped some atmos they recorded out there and it covered things up nicely. There are some very expensive programs that can perform miracles too. A hard one is taking cars out in a busy city intersection leaving a conversation intact.