Fifteen questions on what a compressor actually does, where the technology came from, and when to reach for one. No time limit, no email, answers at the end.
15 questions≈ 6 minutesAnswers explained
0 of 15 answered
01
THE BASICS
Does a compressor make audio louder or quieter?
02
THE BASICS
What does the threshold control set?
03
THE BASICS
A ratio of 4:1 means what, exactly?
04
REACHING FOR ONE
Which of these is not a job for a compressor?
05
REACHING FOR ONE
You want to keep the snap on a snare. Fast attack or slow?
06
REACHING FOR ONE
What is a limiter, really?
07
REACHING FOR ONE
What does a gate do that a compressor doesn't?
08
UNDER THE HOOD
What does a sidechain or key input let you do?
09
UNDER THE HOOD
RMS detection responds to what?
10
UNDER THE HOOD
What is parallel compression?
11
UNDER THE HOOD
A de-esser is essentially which of these?
12
dbx HISTORY
Who founded dbx in 1971?
13
dbx HISTORY
When did audio compression first appear?
14
dbx HISTORY
dbx’s OverEasy describes what?
15
dbx HISTORY
The dbx 160 became a studio standard largely because of what?
A compressor only reduces gain, and only above the threshold. It ends up sounding louder because of the makeup gain applied afterwards, which lifts the whole signal once the peaks are under control.
02
What does the threshold control set?
The level above which compression starts
Below the threshold nothing happens. Above it, gain reduction is applied at whatever ratio you have set.
03
A ratio of 4:1 means what, exactly?
4 dB above threshold comes out 1 dB above
Ratios describe what happens to signal past the threshold. At 4:1, an input 8 dB over threshold leaves 2 dB over.
04
Which of these is not a job for a compressor?
Correcting a room’s frequency response
Room response is an equalization problem — that is what a graphic or parametric EQ is for. The other three are all everyday compressor work.
05
You want to keep the snap on a snare. Fast attack or slow?
Slow — let the transient through, then clamp
A fast attack grabs the initial spike and dulls the hit. A slower attack lets the transient pass before gain reduction arrives, so the snare keeps its front edge.
06
What is a limiter, really?
A compressor with a very high ratio
Ratios of 10:1 and up behave as a ceiling, and infinity:1 is a brickwall. dbx units such as the 166xs put both jobs in one box for this reason.
07
What does a gate do that a compressor doesn't?
Attenuates signal below the threshold
A compressor works on what is too loud, a gate on what is too quiet — silencing bleed and room noise between phrases. That is why they so often ship in the same chassis.
08
What does a sidechain or key input let you do?
Trigger compression from a different signal
Feeding the detector from another source is how ducking works: the paging mic controls the gain reduction applied to the music.
09
RMS detection responds to what?
Average energy over a short window
RMS tracks average level, which is closer to how we perceive loudness. Peak detection catches instantaneous spikes instead. dbx built its reputation on accurate RMS detection.
10
What is parallel compression?
Blending a heavily compressed copy back under the dry signal
Sometimes called New York compression. You keep the dry transients and lift the quiet detail underneath, rather than squashing one signal harder.
11
A de-esser is essentially which of these?
A compressor that only listens to a narrow band
Frequency-dependent compression: the detector listens to the sibilant range and ducks the signal when it gets loud there. The dbx 520 in the 500 Series does exactly this.
12
Who founded dbx in 1971?
David E. Blackmer
Blackmer founded dbx in 1971. He is best known for the Blackmer VCA and for accurate RMS level detection — the two building blocks behind the company’s compressors and noise reduction.
13
When did audio compression first appear?
1930s, in broadcast limiters
Broadcast engineers were building limiters to protect transmitters well before compression became a studio tool. dbx did not invent compression — it made a far more accurate and affordable version of it.
14
dbx’s OverEasy describes what?
A soft knee — compression easing in around the threshold
Instead of a hard corner at the threshold, OverEasy bends into compression gradually, which is much harder to hear working. It became one of the most recognizable dbx features.
15
The dbx 160 became a studio standard largely because of what?
Its VCA and RMS detection
The combination of a low-distortion VCA and true RMS detection let it hold a signal firmly without the artifacts engineers were used to hearing. It is still the reference point for the family.