Orson Welles & the Mercury Theatre, 1938.
In the lingo of microphones, we often use imprecise words to describe sound. The audio from ribbon microphones is frequently called “dark.” Condenser microphones may be called “bright.” But what do these subjective terms mean?
To understand the concept, we must travel back in time. From the 1930s to the 1950s, ribbon microphones reigned supreme in broadcast and recording studios around the world. Then, in the 1950s, condenser microphones suddenly gained favor over ribbon microphones. Why?
Because analog recording came on the scene in the 1950s. Condenser mics accentuated the top-end of the sound due to their highly-tuned capsules. This hyped audio sounded better with the new analog tape recording. Tape’s high-frequency roll-off was well suited to condenser microphones because the analog recording medium tamed the condenser mic's exaggerated frequencies.
The treble roll-off of ribbon microphones was an issue with analog tape’s high-end roll-off and low-end bump. This where the word “dark” came in to describe ribbon mics. The perceived darkness of a ribbon mic was considered too much for tape recording.
According to AEA, a maker of modern ribbon microphones, the natural low-end bump of the tape machine would also add a bit of bass to the condenser sound. This supported the preferred combination of condenser mics and analog tape until the rise of digital audio in the 1990s.
Digital audio had a more neutral sound — something very different from analog tape. Suddenly, condenser mics, which boosted the high frequencies, didn’t sound as good as ribbon mics in this very neutral digital recording environment. Though ribbon mics have a high-frequency roll-off, it is a smooth and natural roll-off that is more akin to what humans hear with their ears.
The old terms — “dark” and “bright” — were redefined for the age of digital. Are ribbons actually now dark or are condensers just hyped to accentuate the highs? Actually, AEA says there is a little bit of truth to both sides. Ribbons are dark in that they have a high-frequency roll-off, just as human ears have a high-frequency roll off.
Today, due to the advent of digital recording, there has been a revival of ribbon microphones from a wide range of manufacturers. Depending on the ribbon mic being considered, high-frequency roll-off can vary widely. Some ribbons are very dark. This is especially notable when far-field ribbon mics are used up close due to the proximity effect. Other ribbons have been designed to be bright and natural sounding. The old days of a single ribbon characteristic are past.
Condenser mics still accentuate the top end. That is by design. More expensive, higher quality condensers are less harsh, but all condensers are hyped to a degree. Thus, they are brighter. However, condensers and ribbon mics in today’s digital world often complement each other and work together.
It is the creative engineer's task to know which kind of microphone — ribbon, condenser type or dynamic — works best for each sound source being recorded. Sometimes dark ribbons sound better than bright condensers and sometimes not. This fundamental choice is today’s ticket to creative recording and a unique sound.
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