Compression, expansion, noise gate, threshold, ratio—what does it all mean? Should you use a software audio compressor like Chris’s Dynamic Compressor, or a hardware compressor connected to your mixer? Also get an Audacity quick tip for seeing, at a glance, where your audio clips and distorts.
Understanding compressor terminology
- Compression—from the top down, sometimes from the bottom up
- Expansion—expands the range of low volume, opposition of compression, quiets small audio
- Gate—Opens and closes to allow or prevent audio
- Threshold—the point above which audio is compressed
- Ratio—how much to compress audio
- Peak limiter—hard wall to prevent audio from exceeding a volume
- Attack and release (hard and soft knee)—How fast to approach and dissolve the compression, “interactive knee” will change the attack and release speed depending on the input volume
Simple to complex compressors
Levelator (free, standalone)—no options Mixer-based compressor knob (built into some mixers)—just a single knob, like on my Behringer Xenyx X1832USB. Chris’s Dynamic Compressor (free, standalone and Audacity plugin)—a few simple options, follow his instructions to unlock the advanced options Hardware compressor/limiter/gate ($80 and up, standalone device)—several knobs, some have more options than others. Such as my Behringer MDX4600 (currently $120). C3 Multiband Compressor (free, plugin with Audacity edition) or Adobe Audition‘s Multiband Compressor (included plugin with $349 software)
Should you use a software or hardware compressor?
Robert from It’s Just Us has a Alesis 3630 Compressor Dynamics Processor and Adobe Audition 2.0 and wanted to know whether he should use the hardware or software compressor. The short answer is that you have to decide for yourself based on the advantages and disadvantages that affect you.
Software compressor advantages
- Edit undestructively after recording
- Experiment with the same audio to see and hear changes
- Compress audio from any source: studio mics, field recordings, or sound clips
- Often has presets to reduce complexity
- Forward-looking compression
- Not real-time
- Extra steps
- Extra processing time
- Processes all or nothing
- The tools may change (Audacity, Audition, Soundbooth, Pro Logic, etc.)
- Channel isolation
- Individualized setttings for each host
- Preventing noise in other tracks
- Compressing only what you want (voices, not music)
- Process in real-time for fast turnaround
- Live audience benifits
- Expensive ($80 and up)
- May require other upgrades, such as getting a mixer with inserts
- Different settings depending on content
- Mistakes are baked into the recording
- No presets
If you’re just starting out with audio compression, stick with a software compressor so you can learn as you experiment. Always keep and unprocessed archive of your recording. If you have extra money and want to optimize your workflow and have almost instant turnaround, get a hardware compressor.
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