Ribbon Mic의 전성시대 -EM에서 퍼옴
http://emusician.com/images/Ribbon-Mic-Roundup-Fig.Atif.gif" class="right" alt="" border="1" height="141" width="180" />FIG. A: The Audio
Engineering Associates AEA R44C bidirectional ribbon microphone (right)
is a replica of the original RCA 44B (left). The mic in the middle is
an RCA 44BX.
Nov 1, 2005 12:00 PM,
By Myles Boisen
A BRIEF HISTORY OF THE RIBBON MICROPHONE
The ribbon microphone, also known as the velocity microphone, was first developed by General Electric (and later by RCA engineers) during the late 1920s, yet its basic design principles endure to the present day. RCA's first production models dated from the early 1930s and include the 44A broadcast model, the PB 17 soundstage microphone, and the 30A lapel mic (see Fig. A). Offering dramatic sonic advantages over the carbon microphones and temperamental condenser units that preceded it, the ribbon transducer concept was simple, elegant, and reliable.
RCA's classic design suspends a light, extremely thin corrugated aluminum-leaf ribbon vertically between the two poles of a large magnet. “The element in a velocity mic vibrates because of the sound pressure difference between the front and the back of the ribbon,” says Wes Dooley of AEA. Its movement within the strong magnetic flux field generates a small AC voltage. That signal is sent to a step-up transformer within the microphone body, which raises the output voltage and also increases the output impedance to a value (typically 150 to 300 Ω) that is optimal for input to a microphone preamplifier.
Because of the mechanical characteristics of the suspended ribbon, sounds that originate at the front or back of the microphone are reproduced evenly over the entire audible frequency range, while sounds that arrive at the sides of the mic — which produce no pressure on the ribbon — are rejected. This polar response is known as a bidirectional or figure-8 pattern and is characteristic of classic ribbon mics. In 1933, RCA introduced the 77A, a cardioid-pattern, dual-ribbon mic. Toward the end of the decade, Western Electric introduced the 639, a unidirectional, dual-element ribbon/dynamic hybrid that combines omni and figure-8 elements.
Spurred on by the movie and broadcasting boom of the 1930s, a number of smaller American companies (such as Electro-Voice and Shure Brothers) began producing microphones, and most of them had ribbon models in their catalogs throughout the 1940s, 1950s, and even into the 1960s. A roster of long-forgotten microphone manufacturers vividly recalls the United States's glory years of industrialism, including such grand names as Altec, American, Amperite, Bell, Bruno, Carrier, Eastern Sound, Lifetime, and Universal.
Overseas ribbon-mic manufacturers included Aiwa, beyerdynamic, Coles, Lomo, Marconi, MB, Oktava, Peerless, Reslo, STC, Toshiba, and Bang & Olufsen (B&O), whose space-age silver-finned ribbon was the inspiration for the design of the Royer R-121. AKG, Neumann, and Sennheiser never marketed ribbon mics, choosing instead to concentrate on dynamic models (which were more rugged than ribbons) and high-output condenser mics. Their technological innovations, resulting in outstanding and versatile microphones such as the Neumann U 47 and M 49, helped signal the end of the ribbon mic's golden age.
A few ribbon mics have persevered in the marketplace, and ribbons have even gained renewed popularity among a new generation of digital recordists. Notable among currently available models is the venerable Coles 4038, which has remained in production unchanged (except for a transfer of ownership) since the mid-1950s. This model, which is listed in the Beatles' recording logs as an overhead mic, was used by Pink Floyd and has often been championed by engineer Steve Albini.
My experience recording with the Coles 4038 has been that it gives you a pronounced and rounded low-end response and can help soften unpleasant upper mids and highs, making it an ideal choice for using on string instruments, electric guitar, organ-and-Leslie-cabinet combinations, jazz guitar, and woodwinds, any of which can sometimes sound scratchy when recorded with large-diaphragm condenser mics.
Despite the signs of a comeback, it is unlikely that ribbon transducers will ever dominate the industry as they did back in the 1930s and 1940s. On quiet sounds and sources that may benefit from a high-end presence boost (such as pop vocals and drums), condenser mics provide a clear advantage. Figure-8 ribbon designs can also be challenging when miking large ensembles or when seeking isolation in studio recording environments. But when used creatively, bidirectional ribbon mics can yield wonderful room ambience, as well as blends of direct and reflected sound, that cardioid patterns cannot. And nothing's quite as sweet as that old-time ribbon-mic sound for rootsy blues, R&B, jazz, swing, retro rock, and certain folk-music styles, especially on acoustic bass, cello, tuba, trombone, and trumpet.
SPECIALTY RIBBON MICS
The new mono mics featured in this roundup are only part of an exciting resurgence in ribbon-transducer technology. The ribbon rebirth was kicked off in the mid-'90s by AEA's Wes Dooley, the country's foremost ribbon-mic enthusiast. After years of selling Coles 4038 mics and repairing vintage RCAs, Dooley decided to market an exact replica of the famed RCA 44.
http://emusician.com/images/Ribbo-Mic-Fig-BB.gif" class="left" alt="" border="0" height="375" width="80" />
FIG. B: The Royer Labs SF-12 is a stereo ribbon mic with a Blumlein pickup pattern.
The cost for being the first on your block to own a new RCA 44 is high, with these museum-quality reproductions selling for $3,000 and up. But by all accounts, the sound of the replicas is equal to or better than the originals.
Encouraged by this success, AEA went on to develop the mics in this article, as well as the stereo R88 ($1,895). That double-ribbon behemoth uses two Big Ribbon assemblies, mounted end-to-end at right angles to each other. Its fixed Blumlein pattern — two figure-8 patterns at 90 degrees to each other — is designed for ensemble and live concert recording, but is also useful as drum overheads or for recording piano, string sections, and vocal groups.
Royer Labs also offers a stereo mic, the SF-12 ($2,495). With a slimmer profile, the SF-12 is basically two SF-1 assemblies placed end-to-end, again in the fixed Blumlein configuration (see Fig. B). Potential applications would be the same as those mentioned for the AEA R88.
The first major ribbon mic innovation in decades — 48V phantom powering of onboard active circuitry — was pioneered by Royer Labs. The R-122 ($1,695) was the company's first model to incorporate an internal FET preamp and custom transformer, creating what amounts to a souped-up R-121. That active circuitry increases output gain by approximately 15 dB, making the phantom-powered ribbon comparable to modern condenser mics in terms of output level. In addition, Royer's new electronics keep self-noise low, and the impedance matching circuitry allows the ribbon to operate at its full potential regardless of the mic preamp's input impedance.
Essentially, those two mics sound very similar. But the increased gain of the R-122 expands its usefulness for recording quiet string instruments, acoustic guitar, timid vocalists, small amplifiers, and toy instruments. Royer Labs also has a phantom-powered version of the SF-12 stereo mic, the SF-24 ($3,795). You can find an in-depth examination of the sonic differences between the R-121 and R-122 in the January 2003 issue of EM, available at http://www.emusician.com" target="_blank" rel="noopener">www.emusician.com.
RIBBONS FROM THE PAST
Vintage ribbon mics offer dependable — or, at the very least, interesting — sonic qualities, and the designs range from classic to quirky. Discontinued oddities such as the Fostex and beyerdynamic printed ribbon mics are recent hybrid innovations, combining aspects of the ribbon sound with a heartier dynamic diaphragm and conventional end-address body.
Before they came up with the ML-52, the Russian Oktava factory made other original ribbon designs such as the ML-16 and ML-17. Those are rarely seen in the U.S. due to the trade restrictions of the Cold War-era.
Obscure ribbon mics from the Golden Age (1940s to the mid-1960s, when solid-state condenser mics nearly eliminated ribbon-mic production) are still plentiful among the used gear and hobbyist networks. Some mics — such as the Western Electric/Altec 639b, which allows the user to mix the output of dual ribbon and dynamic elements and the better RCA models — are collectable, pleasing to the eye, and capable of pro-studio quality.
Used ribbon-mic bargains can still be found at swap meets and flea markets, but often those are broadcast or public-address mics that were cheap and lo-fi when new, and of limited value now. Inflation has severely restricted the market for the best vintage ribbon mics, but presumably with so many good new ribbons coming on the market, vintage prices will return to reasonable levels again. RCA's top-of-the-line ribbons — notably the 44 and 77 series — always represent the best investment in vintage sound and collectability, as long as the body and ribbon have been properly cared for.
PREAMPS FOR RIBBON MICS
In its manuals, AEA recommends using a low-noise mic preamp with at least 60 dB of gain and 1.5 kΩ input impedance for optimum bass performance with its microphones. During the past ten years of reviewing, testing, and recording with ribbon microphones, I have gotten great results with vintage-style all-tube preamps such as the Universal Audio 2-610 and the modified Ampex 350-series amplifiers, as well as top-notch, solid-state preamps made by Focusrite, Grace Designs, Millennia Media, and Sonosax.
“Ribbon mics have lower voltage output and need higher gain,” explains mic-preamp designer John LaGrou of Millennia Media. “Therefore, a mic amp with exceptionally low noise at high gains is essential. Most modern ribbon mics have a well-managed output impedance in the neighborhood of 200 to 300 Ω, hence they require at least 1,000 to 1,500 Ω destination impedance [a 5:1 ratio] for adequate performance. My personal opinion is that a bridging ratio of at least 10:1 — preferably higher — is essential for top performance of most dynamic and condenser mics.
“Some mic preamps offer switchable input impedance settings at substantially less than 1,000 Ω,” adds LaGrou, “but that improperly loads the design criteria of most microphones, including ribbons. Such mic preamps may make nice effects boxes, but it is not what the microphone designer intended.”
RIBBON MICS FEATURES COMPARED
Click" target="_blank">http://emusician.com/images/RibbonMicSpecs.pdf">Click here to download the Feature Comparison Table for ribbon mics.