RCA 44-A

Watch as Vintage King Technician Scott Krause refurbishes a Vintage RCA 44-BX microphone.

The Grandparent Of All Ribbon Microphones

The RCA 44-A is the grandparent of all ribbon microphones. First released in 1933, it quickly began to dominate the worlds of film scoring, studio recording, and radio broadcasts – and ruled the roost for the next two decades. Its angular shape is instantly recognized, and its smooth tone has made it the standard for all ribbon mics that followed it.

Of the four main microphone types; carbon, condenser, dynamic, and ribbon, the ribbon microphone (and the RCA 44 Series) is the only design that has largely remained unchanged since its creation. Only in the 2000s did ribbon microphones see significant advancements in their design and materials.

Unlike its main competitor, the condenser microphone, a ribbon mic does not need a power supply or batteries, allowing for more versatile placement in a studio environment. And the studio is where the 44-A lived – its large size and weight made it too ungainly for remote or location work, where a dynamic mic (also requiring no power supply) was more effective. The mic also proved its worth on the stage for PA use, where it allowed higher gain-before-feedback.

The History Of The RCA 44-A Ribbon Microphone

The roots of all ribbon microphones were planted by Siemens in Germany in the early 1920s, where the concept was first invented by Walter Schottky and Erwin Gerlach. The idea eventually made its way to America, where the great Harry Olson of RCA began developing the principle, using field coils and permanent magnets.

Olson worked on two concepts in tandem: the dual-ribbon design with a unidirectional pattern that became the Model 77-A (with Master Index number MI-4040), and the single-ribbon design with a figure-of-eight pattern that became the Model PB-31. Although it was the first commercially available ribbon mic, only a few dozen PB-31 mics were made in 1931 before it quickly gave way to the classic Model 44-A (numbered MI-4025).

The giant 77-A was a great microphone for applications where only sounds from the front side were desirable, but its size and directionality limited its use. The bi-directional character of the model 44-A (and its cheaper price) made it the go-to mic in the golden age of radio, especially on NBC, which was owned by RCA.

A single-ribbon microphone is inherently a figure-of-eight pattern when suspended in the open air – the vibratory plane of the ribbon creates a lobe of pickup on each side of it. Because of this character, it is perfectly suited for musicians or voice actors to be placed on either side of the mic.

In radio’s early days, many of the programs featured voice actors enacting scenes from dramatic scripts (think Orson Welles and his “War of the Worlds” broadcast). Rather than clustering all the actors on one side of the mic, the 44-A allowed them to face each other, thus enhancing their interaction. The same was true of musicians in live broadcasts.

The null points on the sides of the microphone also allowed for judicious placement of the mic on Hollywood sound stages for the scoring of films. Anticipating and encouraging such use, the earliest operating manual for the 44-A gave detailed instructions on how to set up actors, soloists, dance, or symphony orchestras for the best effect on either side of the microphone.

Construction & Design Of The RCA 44-A Ribbon Microphone

A ribbon mic is also called a ‘velocity’ microphone because the amplitude of the voltage created by the vibrating ribbon is directly proportional to the velocity of the air pressure that moves it.

In the case of the 44-A, the ribbon is a very thin piece of corrugated duralumin, (a copper-aluminum alloy), suspended between the two poles of a permanent alnico magnet (an iron alloy containing aluminum, nickel, and cobalt). The ribbon is only 1.8 microns thick, about 50 times thinner than a human hair, and this allows it to be moved by the slightest changes in air pressure.

The movement of the conductive metal ribbon in a magnetic field creates voltage changes through magnetic induction; these are then run through a transformer in the base of the mic to boost the output (and this could be set for a 250- or 25-ohm load). Virtually the whole microphone is made of metal (except for the rubber shock mounting), making it very resistant to changes in temperature, humidity, and barometric pressure.

Improvements to the magnet resulted in the slightly larger models 44-B (MI-4026, black and chrome, released in 1936) and 44-BX (MI-4027, umber finish or optional Japan Black, released in 1938). These variants featured higher output levels and a slightly wider frequency response of 50 Hz-15kHz.

Judging by the consecutive master numbers, these three variants were probably all made as prototypes at the same time, with the latter versions taking longer to perfect, thus being released many years after the 44-A.

“The RCA 44 is the mic I reach for the most. I love it as a room mic on anything. I use it on drums a lot and as a guitar room mic – sometimes as the only guitar amp mic. It’s great on acoustic guitar as an augment to a condenser, which gives you those bright, airy highs, but won’t quite fill in that low-end like the RCA 44 does.” Tucker Martine | Producer, Musician, & Composer

Artist Who Used The RCA 44-A

One of the most prominent characteristics of figure-of-eight ribbon mics is their ‘proximity effect’. Talking or singing very close to the microphone produces an enhanced bass response that can be quite desirable in certain applications.

The ‘crooner’ type of singer, epitomized by Bing Crosby, produced this effect deliberately, to flesh out and enhance the mellow nature of their singing (and many radio broadcasters followed suit). In effect, these singers were using the microphone as a musical instrument, not just as a tool to replicate their voice.

Although not a ‘crooner’ in the classic mode, Frank Sinatra also made great use of the RCA 44 in his early days of melting the hearts of bobby-soxers in the 1940s. His fellow Italian crooners, Dean Martin and Perry Como, also used the 44 during this era.

A generation later, Elvis changed the role of the singer forever while using the RCA 44 on his records for RCA. Another generation later, John Lennon used a 44-BX on “Yer Blues,” the only time an RCA ribbon mic was used on a Beatles session.

RCA 44-A Variants

To counteract the proximity effect, changing a circuit jumper inside the body of the 44-A offers two settings marked V1 and V2 (for voice) that attenuate the bass response, while a third setting marked M (for music) allows full frequency response. And it’s the frequency response that set ribbon mics apart from the competition in the 1930s.

Although the Western Electric 394 tube condenser had excellent response up to 15 kHz, it was very large and very expensive. Their main dynamic mic from the same period, the 618A, responded a little lower than a ribbon at 30 Hz but only reached 9.6 kHz - far below what the 44-A was capable of.

For music, the clear and affordable choice was the RCA ribbon. But affordability is relative, and the cost of a 44-A in 1933 started at $140, equivalent to about $3400 today. Three options were offered: the Announce, Suspension, and Program versions, whose only difference was the type of mount; a desk stand, hangers, or a very heavy-duty floor stand.

In its heyday from the 1930s to the 1950s, the RCA 44 series was ubiquitous; found in radio stations, music studios, and scoring stages all over America. The list of albums it was used on would be impossible to compile, but practically any professional recording or radio broadcast from this era would have featured one.

The 44-BX even made history when Les Paul used it for taping the world’s first 8-track recording: “How High the Moon” in 1951. Les said that anything sounded good through an RCA 44 - a case of one icon praising another. Countless musicians and engineers would agree with him.

AEA Revives the RCA 44-A

Founded in 1998, AEA Microphones was born out of Wes Dooley's passion for the iconic RCA 44. After more than 20 years of servicing vintage ribbon mics, Wes used methods and tools obtained from Jon Sank at RCA to recreate the 44-BX.

Crafted with authentic new old stock RCA ribbon material, the R44 series faithfully replicates the classic warmth of its predecessor. The series features five variations on the AEA R44C, which is an exact replica of the original RCA 44-BX.

Considered by some to be one of the most musical microphones ever produced, the RCA 44-BX has an instantly recognizable sound with powerful lows from its strong proximity effect, full and rich midrange, and a unique top end that can take the edge off of harsh instruments

"The ubiquitous presence of the RCA 44-BX in broadcast and recording cemented their well-deserved reverence as the pinnacle of RCA's microphone development in the 20th century. We are committed to carrying on the legacy of the 44-BX through our thorough selection of materials to specialized hand-assembly and extensive testing procedures." Julie Tan | Owner At AEA

The Legacy Of The RCA 44-A

The 44-A was discontinued in 1955, being overtaken by tube condensers for recording everything from orchestras to singers to pop groups. But even then, it remained in use, whether it was recording backing vocalists and strings in RCA Studio B to flesh out the “Nashville Sound”, or capturing the flutters in the attic echo chamber for Berry Gordy’s Motown sessions.

The 44 series ribbons might have taken a backseat in those days, but they never disappeared, because nothing else could replicate their tone.

The history that began in the 1930s continues today, as the 44-A can be found in studios all over the world, which is amazing for a design that is over nine decades old! Whether it’s capturing the bite of a horn section, the sting of a guitar cab, the full sound of a drum overhead, or the stylings of modern ‘crooners’, the rich, mellow, and most of all ‘natural’ sound of this classic microphone will always have a place in music reproduction.

Although RCA stopped making microphones around 1973, several brands have stepped in to carry the torch of the legendary ribbon mic design. A testament to this legacy is found in modern versions, such as the 44-A active and 44 Midnight passive ribbons from Stephen Sank’s Cloud Audio, or the meticulous recreations in the R44C series from Wes Dooley and AEA. While it’s not a direct descendant of the RCA 44-A, the Coles 4038 was Great Britain’s take on the classic ribbon design.