Weird waveform, anyone seen this before?!

[musicjunky]

So, this goes on for a lot of the song I just got done mixing, altough it doesn't seem to effect the way it sounds, because it sounds pretty normal, just wondering what might've caused his.

[wedge]

To my eye, they look like air pressure pulses that don't contain any frequency information. For instance, like the "Puhs" and "Buhs" that mic screens are designed to reduce from vocal tracks. You could probably delete or reduce their amplitude significantly, and still hear the notes of the instrument fine...

[musicjunky]

Well, this is the waveform of a whole mix, with a piano and three cellos. maybe i'll see if one of the cello's is having problems, and throw a high pass on it or something.

Here's the a clip what's showing in the picture:Clip

[kdarr]

Well, this is the waveform of a whole mix, with a piano and three cellos. maybe i'll see if one of the cello's is having problems, and throw a high pass on it or something.

Here's the a clip what's showing in the picture:Clip

I'm hearing a periodic "thump" in the bass. My guess is that it's a mic stand being bumped, or the action of the sustain pedal on the piano. I would say it could be breathing plosives from the vocal mic, but I'm hearing it in the instrumental intro before the vocal starts. Unless, of course, you left the vocal track open for the entire intro while the vocalist breathed into the mic, which would totally explain it as well.

[<|>]

[musicjunky]

Yeah, it could be a stand being hit by a cello player, because the sustain pedal wasn't being used, and the vocal track didn't start until right before the vocals.

[Jeff White]

I literally just had a waveform at the end of an electronic song that dipped like that, and it was also in Peak (LE). I was wondering if it is a graphic issue. The sound that it happened with on my end was a slowed down USA quarter spinning. I recorded samples of it back in like 2003 with either an SM57 or Oktava MK012 from above. It only happened after a BTD in Digital Performer,a s it is the tail end of the song.

Interesting, glad that I am not the only one. It sounds fine on my end as well, and running a mastering limiter on the entire song actually cured it. Ozone's mastering limiter/Dither section has a DC offset remover, so maybe this did the trick. I am assuming that this is DC offset.

Jeff

[musicjunky]

Well, it looked like that in pro tools too, i just happened to open it in peak to take the picture. yeah, i'm going to go back and look at the cello parts and play around with a high pass or DC offset. but i didn't think it was that since it still centers around the center line.

[logancircle]

Yeah, I hear that thump, you're right it does sound kindof like a stand being hit or someone releasing a piano pedal. However I am associating it with the cello. When a cellist bows a string/note in one direction and reverses direction fast enough to sustain the note there can be a thud sound because the bow and rosin are sticky and that change in direction makes that noise lik 00:17-00:19sec in this clip. Try a low-cut on the cello and see what happens. It might also just be someone moving around.

[musicjunky]

I just put a high pass at 150Hz on all the cello parts and it definitely helped. I can't hear the thump anymore, and the waveform looks a lot more normal.

Thanks for all the help! I love this forum.

[Professor]

150-Hz is up through the first octave of the cello range. I'm not sure how low the part was written, but you might want to use a steeper roll-off at a lower frequency.
It doesn't seem like foot tapping, because it's not quite that regular. It's not something I've seen on cello before no matter how close the mic has been to the bow. And it seems like the piano is panned more to the right, so the piano pedal doesn't make sense.
It's definitely just a real low frequency, and I can't tell how low. If that scale at the top is minutes, then you're talking like a 1/2-Hz wave - but the catch is that it can effect the other audio. It may just be the kind of seismic stuff you can pickup through buildings, from traffic outside, etc.

But I do notice it seems to go away with the strings & piano, so if you've dropped the low pass there, that would probably do it.

-Jeremy

[logancircle]

If the top waveform is 4 minutes long, and the bottom is the first 03-12sec, then I'm more mystified. Whatever it is, and if waveforms are to be trusted, we should be able to hear it. It looks like a big transient followed by steady and extreme displacements of sound, like a record skipping. This my be an especially good example of the fallibility of waveforms. My guess is that the bassy shit we were all hearing is NOT the same as the waveform anomaly (sp?).

[farview]

I looked at the clip in wavelab and it looks the same.

I got rid of it with a high pass filter at 20hz. If you can go back into the mix and find the track that does this, you could just high pass that. But, it's definately subsonic. You won't miss anything below 20hz.

[vsr600]

I looked at the clip in wavelab and it looks the same.

I got rid of it with a high pass filter at 20hz. If you can go back into the mix and find the track that does this, you could just high pass that. But, it's definately subsonic. You won't miss anything below 20hz.

actually just eyballing the graph you can see the waveform takes about 1/4th of a second to complete, meaning the frequency is like 4 Hz even! yea do a hi pass as low as you want, you don't need to go all the way to 150Hz to catch it. the fuzzy stuff superimposed on the waveform is the higher frequency content you want to keep riding along that 4 Hz bump...

[ashcat_lt]

I've seen a lot of that sort of thing in my digital manipulation phase.

It's a common side effect of modulation effects and probably the thing that led me all by myself to the "hi-pass everything" mentality that many people on this board espouse.

Whatever caused it, the extreme dips are completely outside the audio frequency. You won't hear them, and they're not likely to correspond to anything you can hear. They are eating your headroom though.

Does this show up in any of the individual tracks, or only this final mix?

[musicjunky]

well, little blips of that form were in the cello, but it looked more like a sine wave that was always touching the center line, not like those that go well past it. There were no effects on any of the parts, but i did the high pass, and it looks much better and the bass thumps are gone. problem solved, thanks.