Ask – What's the Recommended Way To Adjust Compressor Parameters?

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API’s 527 compressor is a 500 Series module with the essential threshold, ratio, attack, and release controls, as well as several special-purpose switched functions.

I’m pretty knowledgeable about signal processing, but I just can’t seem to get compression to sound “right.” Either there’s too much or too little. Is there a recommended way to adjust compressor settings?

David Bain

via email

El Segundo, CA

The key to understanding compression is that the threshold, ratio, knee, attack, release, and output gain controls are interactive—if you adjust one control, you’ll likely need to revisit the others. For example, if you lower the threshold to compress more of th

e signal, then the ratio setting has a greater effect, so you may need to reduce it a bit. Increasing the attack time lets through more of the attack, which is less subject to the threshold and ratio controls . . . and so on.

Until you become a compression expert, take advantage of any program-dependent option that adjusts release and/or attack automatically. You can always defeat it to customize the settings.

As a guideline, start with a moderate compression ratio like 4:1, and reduce the threshold until you can “hear” the compression. Now reduce the ratio until you don’t hear any obvious compression effects, and adjust the output gain to match peaks in the bypassed and enabled positions. If there’s not enough compression, reduce the threshold (or increase the ratio) slightly to emphasize the compression.

Incidentally, Yamaha’s “one-knob compression” technology (incorporated in mixers like the MGP Series), is designed to solve this issue. Particularly for live use, reducing compression to a single control lets you dial in the sound you want rapidly, with little—if any—compromise in sound quality.