Peak and RMS

BDiNkY30

BDiNkY30

New member
Though i don't use much compression, I would like to have a better understanding of some of the components. I am an electrical control wiring technician and have a full understanding of RMS and Peak waves RMS constant is .707 and Peak constant is .637. How does this equate to using compression and what are the differences between the two?
 
sorry, i don't understand the question. peak & rms are simply two different views on a signal. the one is instant (peak) & the other averaged (rms). the rms of a 0dBFS sinus is -3dB (0.71 in linear scale). what do you mean with peak constant?
 
Mostly it's how fast the processor responds to the signal. Sound engineers often think in terms of crest factor, or peak to average ratio, a variable with musical signals. A high crest factor is peaky while a low one is not. A square wave has a crest factor of 0dB, a sine wave 3.01dB, half-wave rectified sine 6.02. Music is considerably higher than that usually, and live music even higher.

I encounter those terms mostly on limiters (compressors with ratios of 20:1 or higher). You can do much the same things manually on a compressor with ratio, attack and release controls. With the attack and release set to their fastest speed it is acting on the peaks (though it will affect the RMS to some degree depending on the threshold setting). Slowing the attack/release speed down makes it pass peaks and act more on the RMS of the signal.
 
bouldersoundguy said:
crest factor, or peak to average ratio,.
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Quick question (sort of OT, but not really).

Is "crest factor" the difference between the highest peak and the average? Or is "crest factor" the difference between the highest peak and the lowest signal.
 
RAMI said:
Quick question (sort of OT, but not really).

Is "crest factor" the difference between the highest peak and the average? Or is "crest factor" the difference between the highest peak and the lowest signal.
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crest factor = peak to average ratio

Say a given CD has a peak of 0dBFS and an average level of -11dBFS. That's a crest factor of 11dB, which many would consider over-compressed. Live music is generally much less compressed and could have much higher crest factor, 20dB or more. EDM often has lower crest factor in the LF, something one has to consider when amplifying it.
 
bouldersoundguy said:
crest factor = peak to average ratio

Say a given CD has a peak of 0dBFS and an average level of -11dBFS. That's a crest factor of 11dB, which many would consider over-compressed. Live music is generally much less compressed and could have much higher crest factor, 20dB or more. EDM often has lower crest factor in the LF, something one has to consider when amplifying it.
Click to expand...
Thanx Boulder. Not the first, and probably not the last time I learn something from you.
 
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