SR/Live Sun, November 23, 2008

Sound Reinforcement/Live Sound | Features |

Condenser Microphones For Stage Use - No longer just a studio option

Summary

  • The condenser microphone (also called a capacitor microphone, although the correct name is electrostatic microphone) has long been considered the product of choice in studio environments, where their sensitivity and linear response has been highly valued. Yet in the tough environment of a stage, the condenser has, until fairly recently, been relegated to relatively menial tasks such as drum overheads, percussion, acoustic guitar and the like.

That however, has now changed, and as technology moves forwards and becomes increasingly affordable, more and more condensers are making their way onto the world stages, both in vocal and instrument applications. The reasons are varied, but to understand this, one has to take a look at some of the history and practicalities of the technology.

The condenser microphone was developed in 1916 by E. C. Wente at Bell Labs in the USA to translate sound waves into electrical waves that could be transmitted by a vacuum tube amplifier. His patent 1,333,744 “Telephone Transmitter” was filed December 20, 1916 and granted March 16, 1920. This design was improved over the next 10 years and became in 1926, the Western Electric 394-W microphone used to produce the first generation of sound motion pictures.

Condenser is actually an obsolete name for a capacitor, as the microphone uses a capacitor to convert acoustical energy into electrical energy. The capacitor has two plates with a voltage between them. In the condenser microphone, one of these plates is made of very light material and acts as the diaphragm. The diaphragm vibrates when struck by sound waves, changing the distance between the two plates and therefore changing the capacitance. As such, condenser microphones require an electrical source to establish the capacitor plate voltage, and for internal amplification of the signal to a useful output level, which can be provided by an internal battery or external source.The good news was that condensers tend to be more sensitive and responsive to transients and have a flatter response, especially at higher frequencies. But the downside was the power requirement (batteries can run down and power was not always readily available), delicate capacitors and a reaction to humidity between the plates that can create an audible “fizzing” of the audio output.