Dynamic Range Processors

Limiter

The limiter severely reduces any signal that is above its threshold. Limiting is essentially extreme compression (with a high threshold & high ratio).

Applications

• Controlling sudden transients of high level (safety)
• Preventing distortion
• Increasing the average level of material (making it sound 'louder')

Controls

• Threshold
• Ratio (beginning at a high level)

Risks

• Sound of high transients can become unnatural
• Noticeable when used because of its extreme effect
  [WKRP Broadcast Limiting]

Compressor

The compressor controls the dynamic range by reducing the gain of any signal that is above its threshold, by the amount of the ratio.
Parsons ASSR to 4:40

Remember, compression is among the most difficult of the tools to hear, have control of, and apply confidently.  Practice & gaining experience are the answers!

Basic Controls

• Threshold (When does compression begin?)
• Ratio (How much compression happens?)
• Output or Make-up Gain
• Gain Reduction Meter:  The real key to how much compression is being used!

Compression Ratio

Compression Make-Up Gain

Applications

• Controlling transients
  [Studio Pro CD2/Tk 3 @ 0:45]
• Solidifying a performance
  [Studio Pro CD1/Tk 28] [Studio Pro CD2/Tk 3] [Bartlett Attack Time]
• Keeping all sound within a restricted dynamic range (keeps things from getting lost)
  [Studio Pro CD1/Tk 15]
• Sound design and major timbrel re-shaping
  [PT Special Effect]
• An approach to the process...
  [Dynamics Process: compression]

Risks

• Over-compression can leave tracks dull, flat, or lifeless
• Altering of the piece's dynamic range relationships [Overcompressed]
• Pumping, breathing, or other unwanted sonic artifacts
  Studio Pro CD1/Tk 18

Gate

In its simplest form, the gate silences any signal that is not above its threshold.

Applications

• Controlling bleed into close mics from other instruments
  [Parsons ASSR 6:17-14:21 & 20:33 Snare Gate]
• Controlling noise from loud amplifiers
  [Studio Pro CD1/Trk 19]
• An approach to the process...
  [Dynamics Process: Gating]

Risks

• Doesn't allow for natural decay of sound
• Any sound below the threshold is lost

Controls

• Threshold
• Ratio/Range
• Attack Time
• Release Time

In practice, there are a few other controls to help make the gate more musically useful...

Expander

The expander does the opposite of the compressor– Widens the dynamic range by decreasing the gain of any signal that is below its threshold.  It is essentially a gate with a ratio control, to make it less extreme.

Applications

• Increasing the dynamic range of the performance
  [Studio Pro CD1/Trk 20]
• Driving noise further down in the mix, causing it to be masked
• Reviving an over-compressed performance (maybe, but often not!)
• An approach to the process...
  [Dynamics Process: expansion]

Risks

• Expanding to solve over-compression is not always effective
• Altering of the piece's dynamic relationships
• Pumping, breathing, or other unwanted sonic artifacts

Advanced Compression Controls

Certain compressors (including the Distressors and vintage plug-in emulations) use an input control instead of a threshold. This means the threshold is fixed, but because the input level into the compressor is varied, it can work the same way.

Just be aware that this control will need to move in the opposite direction of a threshold to achieve the same result.

Attack Time

How long does it take the compressor to get to full gain reduction once triggered?

Release Time

How long it take the compressor to stop working?