Notch EQ and Audio Surgery

[roymond]

I'm working on something that has a variety of issues, one of which is a live stereo recording off a board (drums and guitar), which is beautifully capturing some analog clipping in the board (perhaps the kick mic) before going into the DAW. So the digital sound wave is great, and not clipped, yet there are isolated pops from the board that came through the stereo feed.

I need to find exactly at what frequencies these pops reside, then filter them. Does anyone have a recommended efficient procedure to do so? I use Logic and Audacity, but I imagine the specific tool isn't important.

I'm thinking of using two copies of the stereo track. One focused on drums and especially the kick, and the other EQ'd for the guitar and cymbals. Then mixing them together. But I need to nail these pops.

[Billy's Little Trip]

So you only have a stereo L/R track to work with? If so, I'd just focus on cleaning it up with a pop, click or clip filter. Goldwave is what I use and I have a free copy. It works great. As far as isolating the exact frequencies, that's up to you as to how well and in depth you want to use the tool(s).

As far as your board getting a clipping sound that's not showing up in the red on the board, that can be several things. A common issue is a bad mic. They will clip at the mic that will not spike the meter.
Another issue is an inconsistent signal that hits the red once or twice in a song, use a limiter on that track.
Another is too tight of a gate. If a gate isn't set wide or open enough with a hot signal, it clicks when it opens and it won't show on the meter, but shows in the mix.

[roymond]

Thanks! The board isn't mine, so I have no control over that (it's a rehearsal studio). Next time I'll bring my own, I think. We have two hours, and with set up and everything, it's basically just get decent levels and go for it.

I'll dive into Audacity (I'm Mac based, so Goldwave isn't playing) and see how well it goes. It may be that in the greater mix these pops disappear, or at least get covered to the extent that they don't feature so prominently.

[Billy's Little Trip]

Well, as everyone's goal, get the best cleanest tracks you can and as many separate tacks as you can afford.
But if you have pops, clicks and clips, there are several ways to fix them without hurting the integrity of the entire track.

Example: If you have a track with two bad clips/pops, isolate those two bad spots and fix them rather than running the whole track through a filter. Not sure of the mac equivalent to goldwave, but I'll find the bad spot, isolate the peak of the hit, use the filter and ratio to best treat it until it's gone or smoothed out, then make up the lost gain to bring it back up to the rest of the mix. I can generally do this seamlessly. Or at least good enough that no one notices.

[roymond]

The problem is that there is no distinct spike associated with the pops, as most pop/clipping filters require. They almost sound like handclaps, and the digital audio is perfectly normal. These were analog pops in the analog board that were then recorded, faithfully, by my digital gear. They occur often, seemingly caused by the kick with other significant simultaneous events that combined to overdrive some component in the input channel, so they almost sound random and thus don't really pass for handclaps at all. The environment didn't allow me to chase down the specific problem, so I minimized it as much as I could, then threw my hands up and hit record. I may just have to try and bury them in the mix/EQ. Or add lots of handclaps.

[JonPorobil]

Roy, for things like that, I used to use the Spectral Analysis tool that came as part of Adobe Audition. It would lay out the whole track on graph where the X-axis was time in the track and the Y-axis was frequency. Instead of peaks and valleys to represent volume, it output a rainbow chart. Cooler colors meant lower volume, whereas reds and yellows meant louder. You could highlight just one section of red and apply a "reduce by 6db" command to it, which was great for spot-checking little hiccups like what you describe. I don't know of a VST that does the same thing, but one must exist somewhere...

[roymond]

Roy, for things like that, I used to use the Spectral Analysis tool that came as part of Adobe Audition. It would lay out the whole track on graph where the X-axis was time in the track and the Y-axis was frequency. Instead of peaks and valleys to represent volume, it output a rainbow chart. Cooler colors meant lower volume, whereas reds and yellows meant louder. You could highlight just one section of red and apply a "reduce by 6db" command to it, which was great for spot-checking little hiccups like what you describe. I don't know of a VST that does the same thing, but one must exist somewhere...

Ah yes...Spectral Analysis. I am playing...

[Billy's Little Trip]

The problem is that there is no distinct spike associated with the pops, as most pop/clipping filters require.

I was using "filter" as an example. When I said smooth it out, I meant by whatever means needed. Sometimes it's as simple as EQ on that "hand clap" sound. It doesn't matter if it's a peak or valley. Isolate it as close to that exact spot as you can and punch it in the dick until it says uncle.

But hearing you describe it again, it really sounds like a mic issue. Either a mic going bad or an improper mic for the job.
You mentioned that you think it's maybe the kick. Are you using a kick mic? If you don't have one, use a dynamic on the kick. Like an SM57. Try positioning it at an angle or off center if you are micing in front of a kick via head or port hole, sharp air movement will pop a mic.

Since you are going stereo out of the board, you'll just have to catch it on the board. If it's the kick and you're not using a kick mic that's not coiled to cut high, EQ down the highs on it's track.

[roymond]

I agree, I think it was the kick mic, and I just couldn't fix it then and there so that's that. Live and learn.

Fucking drums...

[fluffy]

You might try out Reaper. It has an incredible equalizer plugin which lets you draw the resulting EQ curve with amazing precision - like to the point of being able to filter out individual fundamental frequencies of specific notes. I'm sure it also has a click-and-pop filter as well; I've only just begun playing with it.

The 60-day demo apparently doesn't actually restrict you to just 60 days, either - it just gets naggier after the time expires. (And the full app is only $60 anyway.)

[jast]

I don't know of a VST that does the same thing, but one must exist somewhere...

It's called Spectro. http://www.stillwellaudio.com/plugins/s ... s/spectro/

[JonPorobil]

I don't know of a VST that does the same thing, but one must exist somewhere...

It's called Spectro. http://www.stillwellaudio.com/plugins/s ... s/spectro/

Jan, you just made my life a little bit better than it was before. You should feel proud of that.

Roy, I'd bet the contents of my wallet that this will help you spot-check and reduce those unsightly pops.

[Billy's Little Trip]

I don't know of a VST that does the same thing, but one must exist somewhere...

It's called Spectro. http://www.stillwellaudio.com/plugins/s ... s/spectro/

This is exactly what I've been looking for. But only one pet peeve. I want this in a stand alone, like Goldwave. I like doing my analyzing and mastering separate from my mixing. But I do like it as a VST for individual track work. But still would like it as a stand alone for completed mixed stereo files.

edit: Duh! Before you say it. I can just start a new project in cubase with only the completed mixed stereo file.

[JonPorobil]

edit: Duh! Before you say it. I can just start a new project in cubase with only the completed mixed stereo file.

Or create a Group, route all your tracks to that group instead of your audio device, and apply the VST as an insert to that group.
That's how I master, anyway. Your mileage may vary.

[Billy's Little Trip]

edit: Duh! Before you say it. I can just start a new project in cubase with only the completed mixed stereo file.

Or create a Group, route all your tracks to that group instead of your audio device, and apply the VST as an insert to that group.
That's how I master, anyway. Your mileage may vary.

I don't like using the group feature to master or work on the final finishing touches. But I say, whatever works, stick with it.
It may just be a mental thing that started from previous computers when I first learned about DAWs. Slower computers and heavy VSTs which cause glitches, hurt sound quality, freeze, etc. So I taught myself the best work around methods. After recording and mixing the music, I like to get the mix down done, close it and start the vocal phase in a new project. By this time, it's not unusual for me to have a total of 40'ish tracks with the music and vocal phases combined. Then the third phase is polishing/mastering. I again like everything closed and saved, then start working on the completed mixed stereo file.

I can very easily go back to any of my previous phases and make any little change to a track(s), render the updated version and insert it in the final mix.
Phase 1. Record and mix music. (generally 25-30 tracks mixed to a stereo track)
Phase 2. Record and mix vocals into music. (1 stereo track of the previously mix music and 8-12 vocal tracks)
Phase 3. Polish and master the final stereo mix. (the term mastering used loosely)
That's my method. Keeping in mind I have the song 95% mapped out before I even start recording the first phase. So I know 95% how I want the music panned and fills for phase 2.

[fluffy]

Output groups/buses/etc. work fine, especially if your DAW supports track freezing (or bouncing I think is what Cubase calls it) since then if you realize something needs changing further up the chain you still can, without a lot of extra work.

[roymond]

It's called Spectro. http://www.stillwellaudio.com/plugins/s ... s/spectro/

This is very cool. And very challenging. Not at all as simple as I had hoped, but I think I knew that.
I will plug away until it seems stupid to procede. I am determined to finish the piece.