compression question

[dairyairman]

hey audio experts, i have a little audio problem i can't seem to figure out. i have a recording of my band i made with a single mic. it sounds great, except for one thing, the mic was too close to the snare drum and the snare is way louder than anything else on the recording. i can't increase the overall volume of the recording without clipping those snare hits. i want to reduce the volume of the snare hits. i tried loading the recording into audacity and using its built-in compressor to bring down the volume of the snare hits, but i only could get so far with that. the compressor does level out the dynamics all right, but the peak volume of the snare hits is not reduced. the compressor has an "attack" setting that makes the snare hits more spikey the lower you set it, but it does not reduce their volume no matter how you tweak the compressor. i want to bring down those volume peaks, but i just can't figure out how to do it. does anyone have any suggestions?

[Seafroggys]

the attack setting on a compressor is how long it takes once the waveform breaches the threshold before the compressor begins working. Let's say the threshold is -20 db, and the attack is 5 ms. When the sound passes -20 db in volume, it doesn't compress until 5 ms after it has passed. The longer the attack, the more of the initial "attack" of the sound passes through before being compressed, the shorter the attack, more of the waveform is compressed.

[Motleyguy]

The problem I'm seeing here is, the fact you did the entire band with a single mic correct? That would make it one track? if this is the case, then when you compress, it will compress the entire track, not just the snare hits. You might try turning the output of the compressor down, once you've used the compressor, it'll lower the volume.

[Moseph]

Given the described scenario, it sounds like you may be able to take advantage of equal-loudness contour phenomena with this one.

The way I would go about doing this would be to load up the file in an editor with hard limiting (I myself would probably use Audacity). Based on your description, the peaks of the snare drum are probably several dB greater in amplitude than the rest of the mix combined. Judicious use of a hard limiter can drop those peaks, and only those peaks by quite a bit without creating an audible difference (remember to have a backup of the original file so you don't regret this later though). Then use normalization to bring up the entire mix again. Hopefully only the snare's timbre will be noticeably affected, but then you've also got everything else made louder, so it'll sound more even overall.

[dairyairman]

you're absolutely right. the snare hits look like sharp spikes when i view them in audacity. everything else is several db lower and roughly the same volume.

a hard limiter sounds good. does audacity have a limiter function? i haven't seen anything like that other than the compressor function.

[naut]

with issues like this, one thing i tend to do is use a fully parametric EQ to hone in on the most prominent and aggravating frequencies of the instrument i wish to attenuate, then i just reduce the dB by the amount i want. although i always use that in unison with other gain-based adjustments because obviously if you do anything too extreme it's going to severely affect the tone/sound of the snare. which can of course be a good thing, but more often...it's not.

[Motleyguy]

a hard limiter sounds good. does audacity have a limiter function? i haven't seen anything like that other than the compressor function.

Compressing at a ratio of 10:1 or more is considered limiting. So set the ratio the the max amount you can on the compressor, you'll get essentially the same effect. Keep in mind, you don't want it to sound over compressed, which is a big mistake alot of people make with limiting. So get the highest ratio you can, while it still sounds good. Always keep a back up of the original file.

[Thanks]

You might try some multi-band compression, taking action on the highs. This will attenuate just the high frequencies only when the snare hits occur. This will relieve you of some of the effects of compressing the entire mix, and will not cause the whole mix to become dull the way attenuating highs all across the dynamic range would. Does audacity have a multi-band compressor?

EDIT: Obviously, play around with different frequency bands. The highs might not be where all your issues lie.

[Moseph]

you're absolutely right. the snare hits look like sharp spikes when i view them in audacity. everything else is several db lower and roughly the same volume.

a hard limiter sounds good. does audacity have a limiter function? i haven't seen anything like that other than the compressor function.

I guess I must've downloaded an extra plugin at some point. More info about hard limiters and Audacity is here:
http://audacityteam.org/wiki/index.php?title=Click_Removal

[dairyairman]

well, that was a bit of struggle but i got that hard limiter plugin. on my linux machine i had to download the source code for a fast fourier transform library. compile that. then download the source code for a huge plugin library and compile that too. once i did all that, the hard limiter plugin showed up in audacity, along with about a thousand other crazy plugins. (who knows what they all do?)

anyway, the hard limiter works great! you guys are right. it does tend to basically saw off the tops of waveforms (clip) but it has a setting that lets you preserve some of the original waveform so the clipping isn't so harsh. i was able to bring down the level of those snare hits no problem, which then let me raise the overall volume of everything else. that's just what i wanted.

thanks for all the help!