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AEA KU4 Microphone

The KU4 is unmistakeably a ribbon microphone, with a characteristically smooth ribbon sound. Like other ribbons, its lightly-tensioned, ultra low mass ribbon has a frequency response beyond 20 kHz, an accurate transient response, and no upper midrange resonances common to large condenser mics.

However, having a supercardioid instead of a figure-eight polar response pattern mics sets it apart from other ribbon mics. The KU4’s suppressed rear lobe reduces the pickup of room ambience and is especially useful when the rear of a figure-eight pattern would pick up undesirable sounds. The KU4’s reduced bass proximity effect facilitates closer micing while its low-tuned ribbon will not exhibit bass distortion. These characteristics make the KU4 well-suited for modern studio production.

The Legacy of the RCA KU3A

The KU4 is a re-envisioning of the legendary RCA KU3A, a unidirectional microphone originally designed for the Hollywood movie studios. It combined the smooth ribbon sound of a 44 with a unidirectional pattern, wide sweet spot and reduced bass proximity effect. It became a standard at film studios around the world because it expanded an engineer’s range of placement choices. Today, however, the KU3A is a collector’s item, and few studios or rental houses own them. AEA is proud to put this microphone back into the hands of modern users.

The KU4 is your ticket to discovering why RCA unidirectional ribbon microphones have been used in professional studios for over 60 years. AEA is honored to play a part in its history, and invites you to listen to the KU4 and claim your part of this legacy.


Response Curves

KU4 Polar Response Plot 

KU4 On-Axis Frequency Response Curve

Magazine Reviews

AEA KU4 Review
April 2012, Resolution, by John Thornton
“Where the KU4 really comes into its own is in those situations where spill is an issue. I was forutnate to be able to trial the KU4 in an as-live session incorporating drums, bass, guitar and a small brass section. While acoustic screens provided a degree of control, a fig-8 ribbon for the brass would never have been an optimal solution – however much I like the sound. The KU4 here really delivered the goods. A combination of relative source level, the hypercardioid pick-up, the microphone’s SPL handling and overall sound all seemed to click into place. I’ve employed EV RE-2 in similar situations in the past but they just can’t match the KU4 for wonderful mid-range smoothness that flatters even the harshest sounding players.”

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AEA KU4 Review
Feb 2012, Mix, by Kevin Becka
“AEA KU4 Ribbon Microphone”
“It’s hard not to rave about this mic. Yes, It’s expensive, but the feeling you get when you hear the KU4 in fron fo anything is the resaon audio engineers get out of bed in the morning…The KU4 has an intimate quality that I’ve not heard out of any other ribbon. Using the mic is a joy. For me, the only negative experience I had with KU4 was boxing it up to send back to Wes.”

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AEA KU4 Review
Jan 2012, Pro Sound News Europe, by Russ Hepworth-Sawyer
“AEA KU4 Ribbon Microphone”
“Overall this is a mic that displays no pretense. What you capture is what you get. There’s very little hype of overriding ‘color’ to impose upon your recording other than ribbon warmth. Comparing the KU4 with the flood of new ribbons on the market, you quickly appreciate the RCA heritage and RCA sound the has endured for generations…”

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AEA KU4 Review
Jan 2012, Sound On Sound, by Hugh Robjohns
“AEA KU4 Supercardioid Ribbon Microphone”
“The combination of classic ribbon smoothness with a near-cardioid pattern is a very beguiling permutation that enables the use of ribbon mics in situations that are normally inappropriate or too challenging. The KU4’s only practical imitation, really, is due to it’s size and weight, but if you have mic stands that are up to the job it’s hard to think of an application that wouldn’t benefit from a KU4!”


AEA KU4 Unidirectional Ribbon Mic Features

  • Contemporary realization of the RCA KU3A classic
  • Supercardioid pattern for excellent rear rejection
  • Reduced proximity effect
  • Smooth, high-bandwidth frequency response
  • Authentic New Old Stock RCA ribbon material
  • High-quality anodized & nickel-plated finish
  • Custom AEA transformer, neodymium magnets
  • Consistent Quality
  • Field-tech replaceable ribbon assembly
  • Hand-crafted in Pasadena, California

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