View Full Version : How to fix 'crackling' sounds (i.e. static noise) in recordings?

2007-04-17, 06:55 AM

Last year I taped my first major show (being Depeche Mode at the Ahoy, The Netherlands) and back then I post processed it. However... this was also my first post processing effort, and last December (when being much more experienced in post processing) I came to realise that I had made some major errors on the DM show, so I decided to do the post processing all over, and at present I am at that, and I have run into a nasty situation for which I have yet to find a good fix.

The main issue is most likely caused by the very poor "el cheapo" 3 Euro mic I used for the recording (which, back then, was all I managed to find in time, and which has now been discontinued, in favour of a Sony ECM-717). Not all too surprisingly so, the mic has picked up a lot of static noise (or so I presume it is), and it causes the recording to sound very raw and 'crackling'. I have put up a +/- 40 seconds sample of it at http://www.millennics.com/test/dmbad.wav (+/- 7.7 MB in size).

Now, if you look at the waveforms, you'll readily see that it is very spiky (fortunately not all of the recording came out like this, but at least some 6 or so songs suffer heavily from this), and when playing it back it sounds plainly bad to me (ignore the somewhat muffled sound, this will be taken care of later).

I use Sony's Sound Forge v8.0d for post processing, and I have not yet been able to find a good filter or other way of making this sound better. What I would kinda like, is a filter (or so), that makes the recording sound somewhat more 'polished' and removes the crackling sound.
I tried soft compressing it somewhat, but that didn't do enough magic for my likings. The Wave Hammer works great for bigger spikes (with or without a soft limiting pass included), but often the spikes are not so loud, and consequently it is difficult to set up a good 'selective' wave hammer setting that leaves the desired loud parts alone)...

Can anyone give me some suggestions as to how I could improve this particular aspect of the recording (if need be with additional filters)?

Tnx in advance, and cheers!

2007-04-25, 10:40 AM
Hi again,

I forgot to mention previously that I did already use Sony's vinyl restoration filter, and that did get rid of a lot of the major pops that were present in the initial recording. However, I hope someone wants to have a listen to the sample I put up, and throw in their 2 cents...



2007-04-26, 08:56 PM
those auto crackle fixers will smooth out more than just the crackles... and still miss many of them as well. judging from that sample you're looking at about 10,000+ hours of manually decrackling to get it to sound maybe 20% better than it does in its raw state. The mic upgrade was a good move, looks like you need an upgrade to your recorder (something lossless) and soundcard. Good source recordings don't need audio post, you'll always feel dissatisfied and every year that goes by you'll look back on your previous work and say to yourself "I could do it better now". A raw recording is pure, it is what it is.

the best method for fixing these clicks/crackles that I know of uses Adobe Audition. see here (scroll down)

with soundforge you could try re-drawing the wav using the pencil tool but the process is much slower.

2007-04-28, 03:51 AM

Tnx for the advice!
I too feared that it would be difficult to find a filter that reliably(!) does all of this automatically, WITHOUT the risk of mingling the good audio parts... I'll do my best to give Audition a go (and use the advice given in the thread you refer to), as well as Audacity (which has been mentioned on Tapers section to also have a decent "Audio repair" tool). Also, as I now have a Macbook Pro, I'll try some of the audio editing programs that have been recommended to me in a different thread. Perhaps one of them has a comfortable and not so time-consuming way to achieve this. :D

Also: I totally hear you about not being satisfied with the mixing results as time passes. I remember that about a year ago, I was pretty satisfied with the results on this particular show, but it was when I mixed an Iron Maiden show last December, that I came to realise I had made some major errors in the equalisation process of the DM show, by having forgotten to compensate the total output gain, hence almost certainly introducing clipping (ouch! :rolleyes: ). Regarding the IM show, I think I could do that slightly better too now, but for that particular show the only thing I'd probably change slightly would be to reduce some excessively loud peaks (audience outbursts, mostly), such that the overall normalisation up to 0dB would result in (hopefully) better dynamics, but then, I am quite satisfied with the end result on that show, so I (already previously) decided to do exactly what you recommend: don't look back to it in terms of re-mastering it. ;)
The DM show is a different matter though... When I came to realise the (IMO) gross mixing errors, I couldn't let that one go, and just had to do it over (I'm too much of a perfectionist to not do so, and fortunately I hadn't really spread the first version widely yet). Even now, with the crackling still present, it is already much better than my first version was (well, IMO, at least), and indeed I could live with the crackling, if it proves to be too time consuming. Tnx for your opinion regarding re-mastering; it is a big relieve to see that I'm not the only one who gets dissatisfied with one's own results over time. :cool:

Finally, gear wise, I think I'll keep on using my current gear as much as possible for a little while longer: we just bought a new house and have a baby on the way, so my budget for this is very limited now. The upgrade to the ECM-717 already makes a HUGE difference, and on June 16th this year I intend to use it again (for IM, and some other metal bands). This time I'll perhaps try figuring out a slighty different mic position (rather than on the neck of my t-shirt, which I found to pick up a lot of my own enthusiasm ;) ).
A lossless recorder would be very, very sweet. Especially if it would be of high quality, and HD or CF based. This is something I'll definitely keep my eyes open for, even if such an upgrade may not happen this year...

Tnx again, and cheers!