Software recording compressor?

[camsr]

I need a compressor that will work on my soundcard's input, before the wave data gets recorded into my wave editor. If I had hardware, I would use that, but since I don't, I am looking for a software alternative. Is there something that will help me?

[Andywanders]

You should buy a hardware compressor for this really. The reason being that it will control the dynamics of the signal before it goes into the A/D converters thereby enabling you to record a 'hotter' signal.

There is no way for any software compressor to do its thing until the audio has been converted from analogue to digital, so therefore you run the risk of digital clipping if the input is too high and bad signal-to-noise if it's too low.

[Kiwburger]

This the wrong reason to use a compressor. While a compressor can increase the Average level, it is Peak levels that are important for avoiding clipping while tracking. At the risk of starting a flamefest - a compressor cannot prevent digital overs, and it's a big mistake to use one for this reason. Why? Because a compressor has an Attack time - usually variable. Any loud peaky sound (e.g. a snare) has some transients that will go straight through the compressor, before the Attack time has a chance to kick in and start compressing the signal. While some compressors can be set to very fast Attack times - this usually screws up the sound, and it's a mistake to track with extremely fast Attack times. So this means a compressor doesn't prevent you from clipping your A/D converter. If anything, it complicates your gain structure and adds noise. The only reason to use a compressor while tracking is if you love the sound. A compressor should be considered more like a timbre and envelope shaper - not as a magic bullet for poor gain structure and for preventing clipping.

Some expensive Limiters might be fast enough to stop digital clipping - but that still isn't a good reason to use them. Use them for the sound only - or not at all.

Most people track too hot into their A/D anyway. Set yourself enough headroom, and you won't clip, and you will be working in the sweet spot of the converter, instead of the top 6dB where they can sound a bit grainier.

Then: if you are going to use digital compression - use it at mix time. Don't track with it - there is no reason, and you can't take it off if you screw up.

[camsr]

I didn't think of the A/D. My problem is a dirty preamp, So I am trying to not raise any levels on the signal digitally, so I'm running it VERY hot. I get a -33dB noise floor and that's, well, pretty shitty. I'll look for another way to deal with this. Thanks for the insightful response!

[Andywanders]

...The only reason to use a compressor while tracking is if you love the sound. A compressor should be considered more like a timbre and envelope shaper - not as a magic bullet for poor gain structure and for preventing clipping...

Sure, using a compressor while tracking won't guarantee zero cliping if the gain structure is wrong. But I stand by what I said, especially with regard to vocals. I'm not talking about extreme ratios and gain reduction, just enough to control the dynamics.

But hey, everyone has their own way of working. At the end of the day it's what sounds good that counts.

[BertKoor]

My guess is you aren't using the preamp like you should. A preamp with -33dB noise floor is not usable at all. Did you connect a microphone to a line input, and raised the gain by 60dB or something?

In that case you need another preamp, or a plug adapter to connect the mic into its dedicated input.