What is Compression?
A compressor reduces the dynamic range of a signal — making loud parts quieter and (with makeup gain) quiet parts relatively louder. The two fundamental controls are threshold and ratio.
-20 dB
The level above which compression begins. Lower values compress more of the signal.
4.0:1
How much the signal is reduced above the threshold. 4:1 means 4 dB in produces 1 dB out.
Drag the threshold and ratio sliders — or drag directly on the transfer curve to adjust
Moderate threshold — catching louder moments.·Moderate ratio (4:1) — standard for vocals/mix bus.
Understanding threshold & ratio
Threshold
The level (in dB) above which the compressor begins to act. Signals below the threshold pass through unaffected. A lower threshold means more of the signal gets compressed.
Ratio
Determines how much compression is applied above the threshold. A 4:1 ratio means for every 4 dB the input exceeds the threshold, only 1 dB comes through at the output.
Transfer Curve
A graph showing the relationship between input and output levels. Below the threshold the line follows 1:1 (unity). Above the threshold the line flattens according to the ratio.
Gain Reduction (GR)
The amount (in dB) by which the compressor is reducing the signal at any given moment. More GR means more compression is being applied.
Exam tip: A ratio of ∞:1 is called limiting — no signal can exceed the threshold. This is the most extreme form of compression.