AKG C4500B-BC Condenser Microphone

by Mark Greenhouse

Dynamic and ribbon microphone are inherently sensitive to magnetic fields and may hum and buzz when in proximity to EMF - enough to render some microphones problematic in modern computer-equipped voiceover booths and control rooms.

AKG addressed these issues by developing an RF-resistant, low-cost, 1-inch large-diaphragm condenser mic, the C4500B-BC. This new tool (inspired by AKG's C4000 side-address model) is a front-address cardioid in a cylindrical shape, similar to, but shorter than, an Electro-Voice RE-20.

Features

According to the factory specifications, the C4500B-BC is fairly flat from 50 Hz to 12 kHz, with a 4 dB "presence" bump at 7 kHz. The diaphragm is recessed within the body to allow physical lip-to-grille contact (if so desired), while reducing the proximity bass-boost phenomenon. The diaphragm is made of a plastic foil, gold-sputtered on one side to prevent local shorts to the back electrode, even at extremely high sound pressure levels.

This design also purports to be able to operate in a 90 percent humidity environment, which reduces the problem of shutdown (actual failure of the microphone to transfer audio) caused when moisture created by the breath allows voltage to bridge the element with its frame.

A switchable preattenuation pad allows you to increase the maximum SPL capability of the C4500B-BC by 20 dB for distortion-free, close-in work. A switchable bass cut filter, with its 6 dB/octave slope starting at 120 Hz, reduces rumble or wind noise.

At National Public Radio, our announcers use large-diaphragm, side-address condensers floated in a spider-web-like shockmount attached to a spring-loaded flexible arm. Add to that a "Popper Stopper," and the resulting mass of metal, rubber and nylon forces the reader to position the microphone three inches from their cheek in order to see their copy and the director.

The design of the new C4500B-BC permits substantially better proximity while remaining out of the announcer's sight lines. It also addresses the magnetic interference issue. A condenser element has no coil and is, therefore, impervious to magnetic fields. The attractive pricing of this condenser microphone makes it a sensible consideration.

I spoke with AKG about this product and was told that the C4500B-BC is an application-specific product. In my mind, this translates to "don't expect a miracle when placed in front of a singer or in a stereo pair." Of course it will record other sound sources, but not with the labor-saving, pre-equalized benefits our personal microphone favorites provide.

The best feature of this microphone is the accessibility of its condenser diaphragm to the user's mouth. Add to that a low equivalent noise level to DIN 45 412 (A-weighted) of 8 dB-A, plus a good immunity to RF, and you've got an attractive package.

In use

I near-coincided the AKG C4500B-BC with a spring-tensioned arm dangling a house-brand microphone. I asked a variety of folks to do their tracks, or the reporter's part of a piece. I similarly compared it with a variety of other familiar vocal mics, feeding one to the left channel of an RDAT and the C4500B-BC to the other. In this way, I was able to take the tapes and compare microphones in a variety of environments by flipping between left and right on a stereo channel set to mono.

My initial reaction held true throughout my listening tests. While the AKG provided excellent access to the talent and had a very smooth, well-balanced response, it was noticeably less clear than many of the comparison mics. Additionally, even with the bass rolloff bypassed, the microphone did not reveal the deep, rich tones I am used to in a condenser. I did not research it on any musical instruments, although the specified potential to withstand high dB levels makes it a good candidate for percussion and brass.

While a neutral transducer can be a valuable commodity in a sound field rich in tonal extremes, the AKG C4500B-BC will require equalization to sound "correct." in most broadcast applications. A bump at 3.5 kHz and 80 Hz was required to give the sizzle and size I like my voices to contain. Once EQ'd, the resulting clarity and depth was satisfying.

Summary

A sensible invention with a specific mission in mind, the AKG C4500B-BC accomplishes its mission by providing a low profile, cardioid condenser with excellent RF and EMI rejection.

It can be tweaked to your liking, and most will find it durable and reliable. This microphone is especially well suited for facilities in need of reasonably priced, neutral-sounding microphones for their multiple broadcast booths.

Mark Greenhouse is the training technical director for National Public Radio.

Contact: AKG Acoustics U.S. at 615-360-0499; Web Site