Excessive Crackle

I brought up this subject a couple of years ago, but I thought I would give it another go, since we now have the new and improved DCART in hand.

For a brief period of time (oil embargo era) there was some inferior vinyl being released resulting in an excessive amounts of crackle when played. I am now left with about 25 or so of these releases I am trying to restore.

It seems that most times when I attempt to de-click and de-crackle these recordings, the filters seem to choke on the sheer volume of defects present. I've tried to make multiple passes with very light settings, trying to move to more aggressive settings with subsequent passes with only moderate success.

In most of the cases, I have found CD replacements so I wouldn't have to deal with the recordings in hand; but there are few that are difficult to locate.

Is there a methodology that is recommended for recordings that have numerous impulses?

I might add, that these impulses are not long in duration or not necessarily louder than the program material. It kind of sounds like someone was making a batch of popcorn in the studio during the recording process!

Any ideas would be most welcome.

[Craig Maier]

Hi GB -

I think that I know the sound that you are talking about. If I am thinking of the same thing as you are describing, it is less crackle and more like an ongoing surface noise.

I attack that kind of problem using the CNF rather than the impulse filters, with pretty good results. As you mentioned, the denisity of these noise events is extremely high which confuses the INF, but give the CNF a try and let us know if that helps.

Craig

[Geebster]

Hi GB -

I think that I know the sound that you are talking about. If I am thinking of the same thing as you are describing, it is less crackle and more like an ongoing surface noise.

I attack that kind of problem using the CNF rather than the impulse filters, with pretty good results. As you mentioned, the denisity of these noise events is extremely high which confuses the INF, but give the CNF a try and let us know if that helps.

Craig

Yes, Craig..... The impulses are so dense, it's almost like a continuous event. I have tomorrow pretty much open, so I'll play around with the CNF some, and I'll report my findings here. Thanks for the help.

[Jan Myren]

HI!
Crackle may me troublesome, especially with old 78's. I use the EZ impulsefilter with all the sliders (scratch, crackle and narrow crackle) at about 60 on 20's and 30's 78's. May it be a good idea to take a run with the median filter after that with the 3/0 setting? Is it best to do that in stereo or mono mode, since I normally do recording and EZ in stereo and then convert to mono for bandpass and cnf? All the best jan

[Craig Maier]

Hi,

Here are some things that I know about 78s and crackle. Transfer at 48 or 96 kHz - - - the added bandwidth seems to help with the systems noise discrimination ability. Also, go light on the EZ Impulse filter settings. Use 40-40-75 or something in that range instead of going too agressive with the settings. Use multiple passes through the filter or set up several in the multifilter to remove more impulses. The use and settings of the Median Filter will depend on the sample rate settings used for the transfer. Perform the de-clicking/de-crackling process in stereo - - - then convert to mono when that process is complete. You can then go on to the de-hissing process using things like the CNF or Dynamic Noise Filter, etc.

Craig