Track Compressor setting for drum hits?

nolonemo wrote on 4/30/2008, 1:47 PM
Hi, I'm editing a video of a jazz big band performance. I've adjusted levels (which are generally OK between ensemble and solo sections) to where my peaks are aound -3dB, but at that setting, occasional drum hits are spiking at around +4db, and especially during drum solos. (I've already dealt with some applause clipping by applying an audio envelope.)

I figure if I set the fx Track Compressor to -2dB Threshold and apply some reduction, I can bring down the spikes without affecting anything else. Is that right? What should I set the Amount at? Or should I just increase Amount until output doesn't clip? Are the default settings of 15ms and 250ms for Attack and Release appropriate?

Thanks for any help, I'm pretty clueless when it comes to audio....

Comments

farss wrote on 4/30/2008, 3:12 PM
You'd probably do better asking in the audio forum.
I'll have a go though at probably giving you the wrong answer :)
I think your attack time is too long to catch the drum hits.
The default track compressor isn't anything too flash though, it's useable and that's about all. A multiband compressor gives you more control.
Do be careful using too much compression, moreso with jazz. Your final waveform looked at zoomed out should have some "air between the trees", it shouldn't be just a solid mass. Do monitor what you're doing with reasonable monitors too. Make certain you're taming but not killing the fast transients from the cymbal hits, they should be the highest spike in the waveform.

Bob.
John_Cline wrote on 4/30/2008, 9:10 PM
Actually, for drum hits and applause, WaveHammer would be a much better tool.

You can either create a new bus or apply it to the master bus. To apply it to the Master Bus, click on the "Master FX" button above the master audio fader. Go to "Sony" and select "Wave Hammer." On the Compressor tab, click on "Bypass Compressor", then go to the "Volume Maximizer" tab. Set the release to 20ms (or maybe less) and start the track playing. Bring the threshold down until it starts catching the peaks on the drums, but little or nothing of anything else. You can try the "Longer Look Ahead" button and see how that sounds. As with all audio effects, you make your final decision using your ears.
Hulk wrote on 4/30/2008, 9:11 PM
I wouldn't compress the snare drum but I would limit it just a bit so that you can control those peaks. I don't want to come off like an audio snob here but the Vegas audio plugs for the most part aren't up to the quality of the rest of the application so if that is all you have access to I would use the wave hammer plug. Bypass the compressor and just use the volume maximizer to tame those snare hits that would normally pop into the red. If you can hear it you've gone too far.

If the mix sounds good otherwise then just put it on the snare. If there are other things in the mix popping out now and then I would put it on the whole mix but for a jazz recording you want to keep it as dynamic as possible so use a light hand.

The Waves Ultramaximizer is a really great sounding unit for this application, among others out there of course.

- Mark
farss wrote on 5/1/2008, 12:10 AM
For a bit of inverted audio snobbery a couple of years back one of the guys from the audio forum mixed a heavy metal album with nothing more than the stock Vegas plugs plus one freebie that enabled him to sidechain.
Unfortunately he posted the tricks in a now defunct forum but it's not that hard to workout how to do things like ducking once you have the plug that'll pull one channel out of a stereo buss.

Bob.
craftech wrote on 5/1/2008, 6:15 AM
nolonemo,

Are you actually hearing the spikes?

I usually leave them. You will probably lose that crispness by compressing it.

John
nolonemo wrote on 5/1/2008, 9:16 AM
Actually, the drum and cymbal hits sound fine in the mix, I just saw that they were clipping on the mixer VU meter.
Guy S. wrote on 5/1/2008, 11:42 AM
<occasional drum hits are spiking at around +4db>

What you are seeing are transient spikes -- sounds that are very short in duration. Your goal is to limit these spikes without noticeably altering the rest of the audio program. Here's essentially what you're trying to accomplish:

Imagine sitting at a mixing console. You've got your hand on the fader, and every time there's a drum hit that peaks, you bring the fader down. How quickly you react is the Attack Time.

After the transient audio spike passes, you raise the fader back up to its normal level. This is your release time. If you're too slow on the release, then the non-offending audio is going to be at a lower level until you raise the fader back up.

How far you bring the fader down when the spike hits is your Ratio. If you reduce the program volume so that a 10dB spike only produces a 1dB change in volume, then you've achieved a 10:1 compression ratio.

With that basic background, and with the understanding that every program is different, here's where I would start:

Attack time: Very short, as you need to capture the transients; try 1ms.

Release time: You want to release as soon as the transient is over; try 10ms - and increase it if you need to.

Threshold: A couple of ways to get here, Soft Knee or Hard Knee (check box near bottom of dialog). With Soft Knee, the ratio increases gradually as the sound increases in amplitude, for a more natural sound. If your final output level for this track is -3dB, then I would start with a Soft Knee ratio 6dB below that (-9dB).

Ratio: Start with something relatively high, say around 9:1.

You will likely need to work the Threshold and Ratio a bit to get the results you want. Highlight a portion of the track that is clipping and loop the playback as you adjust these controls. Your goal is to limit the peaks without noticeably altering the sound. Here's what I would do:

With the offending portion playing with the settings above, look at the levels. Still peaking? Try setting the Attack to 0ms. If that solves the problem, then you'll know that there was only a very brief transient causing the clipping, so try backing off the Threshold by raising it to -8dB, -7dB, etc.

If that doesn't solve the problem, then uncheck Soft Knee. If that solves the problem, then raise the threshold and/or reduce the compression ratio until you get the most natural sound possible.

Finally, listen to the portion of the track that wasn't clipping -- does it still sound good?

There's so much more you can do to optimize the settings, but this is a relatively simple approach that should get the job done rather painlessly.
craftech wrote on 5/1/2008, 12:09 PM
Actually, the drum and cymbal hits sound fine in the mix, I just saw that they were clipping on the mixer VU meter.
========
Then as I suggested, leave it alone.

John
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