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Old 04-12-2008, 09:56 AM   #39
Baer
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Join Date: Sep 2006
Location: San Francisco, CA
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Teej, the RMS value affects how quickly the compressor reacts, so it, along with the attack and release settings has a big effect on the results when using sine wave input as in this test. For example, a 5 khz signal goes through a cycle every 20 ms. So with low RMS and attack values, your release time of 100 ms pretty much makes the compressor a volume control for the upper half of the audible range since it will never release. You’ll see little to no distortion at the higher frequencies.

Another item people should take into consideration when running this test is the effectiveness of the limiter. It would be good to put the JS: Analysis/gfxscope (or some other volume checking tool) in front of the spectrograph to check that the limiter/compressor is holding the volume at the desired -6 db level. Do this with the Kjearhus Classic Master Limiter, for example, and you’ll understand why you get a very clean spectrograph at any setting of the limiter.
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