Technology

Ribbon Renaissance

REBIRTH IN RE-ISSUES, INTRODUCTION OF INNOVATIVE DESIGNS 9/01/2004 8:00 AM Eastern

Everything old is new again. When ribbon mics emerged in the 1930s, their “natural” sound, directional characteristics and noise-reduction capabilities offered distinct sonic advantages over their predecessors in broadcast, film and music recording. A few decades later, with the introduction of lightweight, sturdy condenser microphones, ribbons were suddenly considered unwieldy and impractical, and with the exception of a couple diehards, production all but stopped. But as the microphones disappeared, the legend lived on and classic ribbons grew very difficult to come by.

The qualities that make them prized are many: “Warm,” “musical” and “syrupy” are words often used to describe a ribbon mic's trademark sound, which is attributed in part to a gentle proximity effect that becomes pronounced within a few inches of the mic, as well as an inherently flat frequency response with a smoothly attenuated top end. They're naturally bidirectional, perfect for both mid/side (M/S) and Blumlein stereo recording techniques. In addition, the low mass of a ribbon diaphragm allows for fast transient response. Ribbons also offer a wide dynamic range, useful on everything from capturing low sounds from stringed instruments to handling extreme SPLs at high frequencies, making them an ideal choice for miking brass and percussion.

But such sensitivity also means that ribbon mics are fragile and require special handling. The ribbon element is quite delicate and can be destroyed by strong gusts of air, voltage spikes or even by storing the mic horizontally. (See “Care and Feeding of Ribbon Mics” on page 46.) Because conventional ribbon mic elements translate very subtle movements of the ribbon into tiny voltages, output levels are extremely low and the choice of a preamp is very important. There is the opportunity for more control over the sonic character of a signal, but because much more gain is needed, the preamp must be clean at high gain levels. (Also, be sure to choose a preamp with a relatively high input impedance. Several manufacturers recommend that the input impedance of the preamp be five times the output impedance of the mic, because a ribbon mic's output impedance can fluctuate when source material reaches the ribbon's resonant frequency.)

Although only a handful of manufacturers produce ribbon microphones today, there are a variety of design options from which to choose. At one end of the spectrum, purists at AEA craft exact replicas of the venerable RCA 44 and 77 ribbon designs that reproduce every classic detail, right down to the original aluminum-element material. At the other end, Royer has taken advantage of modern manufacturing technology to introduce such “radical” concepts as active circuitry and dual-ribbon elements for stereo recording. If you're thinking of adding a new ribbon to your mic collection, be sure check out the following models.

RIBBON OPTIONS

After two decades of using, servicing, and selling both vintage and contemporary ribbon microphones, engineer and mic designer Wes Dooley, head of Audio Engineering Associates (www.wesdooley.com), began experimenting with his own ribbon designs, and in 1998, released a handcrafted re-creation of the legendary Large Ribbon Geometry (LRG) RCA 44 ribbon microphone. (See “Radio, ‘Talkies’ and Birth of the Ribbon” on page 44 for more on vintage ribbons.) AEA also manufactures two “big ribbon” originals: the music-friendly R84 and the new R88 stereo microphone. The ribbons, which are more than two inches long, are made from aluminum leaf originally manufactured for RCA in the '70s.

AEA R44 shell

The R44C ($4,000) is a replica of the RCA 44B/44BX, incorporating a 1.8-micron ribbon made from material originally manufactured by RCA, and features a black and silver “radio” finish with polished chrome grille, yoke and cushion-mount. R44C parts are interchangeable with the original RCA 44B and BX. The mic comes with a hard-wired XLR output cable and shock-mount/mic stand adapter, all housed in a vertical case for proper shipping and storage. The AEA R44CNE International Edition ($3,000), introduced in 2001 to honor NAMM's 100th anniversary, combines elements of American and English RCA 44 production for reduced weight and hum sensitivity. An “X Motor” Option ($450) offers 6 dB more output than the original RCA 44B and BX, with a slightly more “forward” sound. Other options include the M Option ($100) for hand-tuning to stereo-match a pair of new R44 mics, an R44CNE chrome-finish grille and custom case options.

AEA's R84 ($1,100) is an all-purpose mic that combines design elements of the 44 and the British 4038 ribbons. The R84 boasts -52dBV/Pa sensitivity, extended frequency response (to 20 kHz) and, like the R44, better than 165dB SPL handling above 1 kHz. The R84 comes in a foam-lined case and includes a shock-mount and 10-foot cable. A R84DJV variation ($1,200), optimized for close-up voice reproduction with adjusted proximity effect and heavier protection from moisture and windblasts, and a matte-black R84 TV version ($1,200) are also available.

The R88 ($1,895) incorporates a matched pair of LRG figure-8 ribbon elements oriented at 90 degrees from each other in one microphone. The R88 transducers evolved from the R84 but are more exposed, imposing minimal hardware between the musicians and the matched ribbon elements. This 14×2.5-inch mic offers -52dBV/Pa sensitivity and 165dB SPL at 1 kHz. Output impedance is 270 ohms. The black “stealth-finish” R88 includes cable and built-in shock-mount, plus a locking angle adapter for flexible positioning.

AEA also manufactures museum-quality RCA 44 and 77 Series shell reproductions and props, including an RCA 44 replica internally prepared to mount a compact side-address microphone (such as a Schoeps CMC64V) inside. Custom mic flags, plaques and lamps are also available.

Beyer M130

Beyerdynamic (www.beyerdynamic.com) offers three ribbon microphones. The M130, designed for an “uncolored” sound, is a compact mic based around a double-ribbon element offering a figure-8 pattern and is ideal for use with Beyer's M160 for true M/S stereo recording. The M160, designed for instrumental miking and M/S recording, is also a double-ribbon design, this time featuring a hypercardioid pickup pattern.

The M260, optimized for vocals and speech in broadcast or recording situations, features a single-ribbon design with a hypercardioid pattern and has a built-in highpass filter. The mics come with threaded microphone clamps; optional accessories include cables, stands and pop screens. The M130 and M160 state an output sensitivity of 1 mV/Pa, and the M260's output sensitivity is 1.2 mV/Pa. The M130 and M160 retail for $599; the M260 retails for $349.

Coles 4038

A classic mic still in production after more than 40 years, the Coles (www.coleselectroacoustics.com) 4038 ($1,400) was originally designed by the BBC as a broadcast recording mic, but is used today in a variety of studio applications. The bidirectional mic features hum-balanced wiring and a magnetically shielded transformer, and is contained in black-enameled brass housing with perforated brass grille. Mics come in a foam-lined rigid plastic carrying case with mount and XLR connector; options include stand adapters, elastic suspension for use with booms, velvet storage bag and a custom case package for matched pairs. A limited-edition bronze-finish Millennium Edition 4038 ($1,600) comes in a wood collector's case and features a custom solid brass shock-mount/stand adapter.

The bidirectional 4040 ($1,500) is the newest ribbon mic from Coles, designed for extended top-end frequency response (said to reach 30 kHz) and higher output. The 4040's ribbon/magnet assembly includes its own internal shock-mount, which can be secured for transit, separating it from the main body of the microphone. The gold-plated mic comes with an adjustable, universal stand-mount and a hard storage case. Sensitivity for both mics is -65 dB (1V/Pa); distortion is less than one percent at 125dB SPL. Impedance is 300 ohms; the 4038 is available in a 30-ohm version for long cable runs and special mic pre's.

Another Coles classic, the 4104B ($800) was originally developed by the BBC for commentators and is commonly used today in mobile satellite broadcasts and other excessively noisy environments due to its high degree of noise cancellation. The aluminum ribbon is protected by fine nylon gauze, and the mic is secured in a brass, perforated case with PVC-covered handle. A “press to talk” button and handy hygienic kit with plastic clip-on screens are optional.

Nady RSM-2

Known for 25 years for its wireless mic technology, Nady Systems (www.nady.com) recently branched into ribbon microphones with the introduction of the RSM-2. Retailing at $439, the RSM-2 is based around a low-tension, 2-inch-long, 2-micron-thick ribbon design, with a figure-8 pattern and a stated 165dB SPL capability. Construction is turned-brass, featuring internal shock-mount construction; the grille assembly is available with a choice of gold or platinum finish. The mic ships in a soft padded carrying case and includes an integrated yoke stand-mount and XLR cable; a pop filter is optional.

Oktava ML52

Russian manufacturer Oktava (www.oktava.net), once that country's largest supplier of microphones (even supplying transducers to the Russian space program), returned to ribbon technology after a long hiatus with the debut of its ML52 a few years ago. The mic features a double 25-micron-thick aluminum ribbon element with a classic figure-8 pattern. ML52 specs include 1mV/Pa sensitivity. The ML52 lists at $299, including foam-lined carry case and stand-mount. A shock-mount is optional. Oktava recently introduced the MA2 preamp, designed to match the impedance of Oktava mics.

Rather than emulate the classics, Royer Labs (www.royerlabs.com) microphones employ sleek modern designs that take advantage of current magnet developments, materials and mechanical construction. Five mics are available: Royer's first mic, the R-121 ($1,195), released in 1999, incorporates a 2.5-micron aluminum-ribbon element in an offset design that allows for a brighter response on one side of the figure-8 than the other. The R-121 can take 135dB SPL, and offers sensitivity of -53 dBV, ref. 1V/Pa. Output impedance is 300 ohms (200 ohms optional) and satin-nickel and black-matte chrome finishes are optional. The R-122 ($1,695) was the first in Royer's Active Series, which introduced (gasp!) phantom power to the world of ribbon microphones, to address gain and impedance-matching issues. The Active Series mics contain fully balanced, discrete head amplifier systems with ultralow-noise FETs. This system is said to handle 135dB SPL and gives the R-122 13 dB greater sensitivity than the R121, with the same sonic quality. Both R Series models are traditional bidirectional patterns.

Royer SF-1

In Royer's SF Series, the SF-1 ($1,395) is a compact, classic figure-8 model. A low-mass, 1.8-micron ribbon is housed in Royer's proprietary cross-field motor assembly, designed with four powerful neodymium magnets and permendur iron pole pieces for the shortest front-to-rear ribbon path length, which improves high-frequency response. The mic's iron case forms the magnetic return circuit, which allows low-leakage flux for higher sensitivity. The matte-black SF-1 is a mono version of the original mic in Royer's SF Series, the Royer/Speiden SF-12 ($2,495), a stereo coincident ribbon mic based on a Bob Speiden design with two matched “microphones” placed one above the other, each aimed 45 degrees from center. Sensitivity is less than -52 dBV (Ref. 1V/Pa). Output impedance is 300 ohms. The brand-new SF-24 phantom-powered stereo ribbon mic ($3,795, see review on page 134) offers the same sonic performance of the SF-12, with Active Series technology for impedance-matching and 14 dB greater sensitivity (-38 dB). Output impedance is less than 200 ohms. All Royer mics come with socks and protective wood cases; options include shock-mounts and windscreens.

Fans of ribbon mics, rejoice: Whether you're looking for a perfect reproduction of a classic model or something completely new, there's a microphone for you.


Sarah Jones is Mix's features editor.

How Does a Ribbon Mic Work?

A ribbon microphone is a type of dynamic mic in which a thin, corrugated strip of aluminum suspended between two poles of a strong magnet serves as the diaphragm and voice coil. The ribbon reacts to velocity of air particles (rather than the pressure, as with moving-coil dynamic mics), and as it moves within the magnetic flux field, it generates a small AC voltage proportional to this velocity. Clamps attached to either end of the ribbon also serve as contact terminals: Wires carry the signal to a step-up transformer, which then raises the output voltage and boosts the output impedance to a usable level for a preamp, typically around 150 to 300 ohms.

Because the ribbon element responds to sound waves arriving from the front or back, but is insensitive to sound coming from the sides, most ribbon mics have a natural bidirectional polar pattern (see diagram above), which makes them ideal for eliminating unwanted noise between two sources or for use in M/S and Blumlein stereo recording configurations. Classic ribbon designs do not contain internal electronics — just the ribbon, magnets, transformer and occasionally a passive highpass filter network.
Sarah Jones

Top: A ribbon suspended between two poles of a magnet responds to the velocity of air particles moved by a sound wave. Bottom: A ribbon microphone is characteristically bidirectional. Sound arriving from 0° and 180° generates movement, while sound arriving at 90° and 270° is rejected. A figure-8 pattern is also known as a cosine pattern, expressed here as r = cos q.

Radio, “Talkies” and Birth of the Ribbon

Ribbon or “velocity” microphones were developed in the 1920s by engineers at RCA, with the first commercial model, the 44, appearing in 1931. The 77A ribbon microphone, introduced a few years later, combined two ribbons (one velocity and one pressure-type) for a unidirectional (cardioid) pattern. The ribbon element design, which offered superior directional characteristics for reducing noise and improving speech intelligibility, was instantly embraced by the broadcast and recording industries. In addition, the “talkies” movie boom created a huge demand for directional microphones, and many manufacturers in both America and Europe, including IBM, Shure, Electro-Voice, Bang & Olufsen, Western Electric and Marconi, began developing ribbon mics. Some notable examples include the STC 4033A, which was produced to meet the needs of talkies and contained ribbon and moving-coil elements, with variable pickup patterns; and Beyer's first durable “short-diaphragm” ribbon mic. In addition, the BBC designed many successful ribbon mics for its own use, such as the legendary PGS, which was later manufactured by STC as the 4038, taken over by Coles in the 1950s and is still in production today. Ribbon microphone development peaked in the '40s and '50s, but these fragile, heavy designs fell out of favor during the next decade, eclipsed by the development of new smaller and lighter condenser microphones. With the exception of a handful of models, ribbon mic production stopped until the late 1990s, which ushered in the era of re-issues, vintage reproduction and new high-tech designs.
Sarah Jones

Ribbon Mics i n Action

Using ribbon mics in the initial recording of percussion tracks can definitely make life easier when it comes to mastering a recording. Here's how it works: If you have the Michael Jackson album Off the Wall, listen to “Don't Stop 'Til You Get Enough.” Listen carefully to the percussion: It is Michael and his brothers playing glass bottles. I wanted the glass bottle percussion in this piece of music to have a unique sonic character and a great deal of impact in the final mix.

The year was 1979. I used a mic technique that came from my experience during the days when it was difficult to put much transient response on a disc. I used all ribbon, or velocity, microphones to record the glass bottle percussion section. The mics I chose were my RCA 77DXs and RCA 44BXs.

If I had used condenser microphones, with the condenser mics' ability to translate the entire transient peak of the bottles, the bottles would have sounded great played back from tape in the control room, but when it came time to master, such an incredible transient peak would have minimized the overall level — on disc, cassette or CD — of the entire piece of music. In other words, condenser mics would have compromised the dynamic impact of the sonic image of the entire piece of music. < /hr> Legendary recording engineer Bruce Swedien is currently in the studio with Ricky Martin.

Care and Feeding of Ribbon Mics

By Wes Dooley
We recording engineers often swap stories about tough lessons we've learned: We remember when we didn't record a rehearsal that was the best performance. We learn that media is cheap and performance magic is unpredictable. Here are important lessons we've learned about using ribbons, ranked roughly in order of importance.

  • Strong wind is an enemy. Don't blow into a ribbon microphone. A ribbon element is as thin as any condenser diaphragm and it's only clamped at the ends. This is good for bass and smooth, fast transients, but large air movements can stretch a ribbon to the point where the sound quality changes. Air movement can be caused by theater curtains closing, slamming a mic case shut or spring breezes when the cartage company opens studio doors.

  • Don't leave your amp turned up when changing an instrument. Air blasts are a ribbon's worst enemy. If you don't turn the amp down when you plug an instrument in, the speaker cones try to launch themselves out of the cabinet.

  • Cover a ribbon microphone when not in use. This protects it from wind and “tramp iron,” the fuzz that covers a magnet after dragging it through a sandbox or across a workbench. If enough gets collected, it will obstruct the ribbon.

  • Phantom microphone power can snap a ribbon if you have a shorted mic cable or bad power supply. Usually, a ribbon mic ignores phantom power. Rarely, however, is not never, as we know well from repairing mics. Turn off the phantom power a few minutes before plugging in and let the voltage bleed off.

  • Store long ribbon mics vertically. The middle of the pleated ribbon can droop from the pull of gravity. This lowers the tension, which can dull the response or cause the output sensitivity to change, depending on where the ribbon flops in relation to the magnetic gap.

Weird Ribbon Mic Tricks

By George Petersen
A ribbon mic in front of a kick drum is a recipe for disaster, as the drum's enormous air pressure can instantly distort/destroy the mic's sensitive ribbon. However, you can often get a huge — yet safe — kick sound by laying a ribbon mic on a pillow inside the drum, with the mic's element pointing straight up toward the ceiling so the air flows across (and not into) the mic. For guitar overdubs, try putting a ribbon (or other figure-8 mic) between two 4×12 cabinets that face each other. As the back side of a figure-8 mic is out-of-phase with the front, wire one of the 4×12s out-of-phase, experiment a bit with mic-to-cabinet distances and you've got a massive guitar sound like no other!

• Read Wes Dooley's take on ribbon mics here.

Click here to read Dooley’s article on the value of preamps.

• Kevin Becka reviews the AEA R84 ribbon mic. Click here.

• George Petersen reviews the Oktava ML52. Read it here.

• Want to know how to care for classic gear? Click here.

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