AEA KU4 Unique Passive Ribbon with Supercardioid Pattern Mic
The Supercardioid Ribbon
The KU4 has the unmistakable characteristics of a smooth ribbon sound, yet it is uniquely different. 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. 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 miking, while its low-tuned ribbon does not exhibit bass distortion. These characteristics make the KU4 well-suited for the modern studio. It is currently the only supercardioid ribbon microphone in commercial production.
The Legacy of the RCA KU3A
The KU4 is a re-vision of the legendary RCA KU3A, a unidirectional microphone originally designed for the Hollywood movie studios. Also known as the “10001” (for its RCA manufacturing number), it was RCA’s most expensive ribbon microphone and fewer than 600 units were ever manufactured. The KU3A combined the smooth ribbon sound of a 44 with a unidirectional pattern, a wide sweet spot, and reduced proximity bass boost. Expanding an engineer’s range of placement choices, it became a standard at film studios around the world. Today, however, the KU3A is a rare collector’s item, and only a handful of studios or rental houses own them. The few lucky owners of vintage KU3As in great condition like Grammy-winning producer/engineer Kevin Augunas (Sound City Studios) treat their mics as little treasures. Original KU3As are notorious for their sonic inconsistencies due to production tolerances, so with the KU4, we at AEA engineered the microphone from the ground up in order to recreate this seminal design while ensuring flawless consistency from unit to unit. 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.
The KU4 utilizes a medium sized ribbon unlike all other AEA mics. While AEA’s Large Ribbon Geometry TM design offers advantages like extended bass response and maximum SPL level, the KU4’s shorter and narrower ribbon is characterized by a unique upper midrange presence that is particularly interesting for vocals and acoustic stringed instruments. Because of the shorter ribbon, the KU4 is much more similar to the venerable RCA 77 type microphone rather than the RCA 44. By comparison to the 77, the KU4 has a slightly longer ribbon, a fixed polar pattern, and a more natural sounding unidirectional mode.
– Unidirectional (supercardioid) pickup pattern
– Reduced proximity effect and room ambience
– Extended top end with classic ribbon smoothness
– Modern, consistent version of the RCA KU3A
Applications & Audio:
Because the KU4 is a supercardioid microphone, it has some exceptional characteristics that are not present in most other ribbon mics. The KU4 has the tonality of a ribbon mic, but cuts through a mix in a way that is more similar to a cardioid condenser or moving-coil microphone due to its polar pattern.Try using the KU4 for a warm, clear vocal sound. The smooth character of the KU4’s treble response means that it may be extensively shaped and processed without risk of nasty resonance artifacts.
Start by placing the microphone 8 to 24 inches (20-60 cm) directly on axis from the singer. The closer the singer is positioned to the microphone, the stronger the proximity effect. To accentuate the low end of a singer, have the performer move as close to the mic as possible without physically touching it. The ribbon is well protected from damaging plosive blasts, but to avoid noises from wind blasts, we recommend using a pop filter.
You may find that some singers sound best from 2 inches away while others sound best from 2 feet (60 cm) away. Depending on the voice, room, and song, different distances work better than other. The distance of the KU4 from the source has a significant effect on the sound of the mic.
Electric Guitar and Bass
The KU4 can handle very high sound pressure levels allowing you to place it close to amplifiers. Watch out for wind blasts, percussive players, and very loud bass cabinets that push air.
Identify where the center of the speaker cone is located and place the KU4 a few inches away from the speaker pointing right at its center for a very direct, “in-your-face” sound. This is the spot where you will get the most high-frequency content. If it sounds too harsh, try moving the microphone to the side parallel to the speaker. You can also try positioning the KU4 at an angle. You will find that small differences in positioning can make huge differences in the sound, so experiment until you find the spot you like.
Acoustic Guitars, Baritones, and Mandolins
When recording a solo guitar a good starting point is to position the KU4 four to six inches (10-15 cm) away from the guitar roughly pointing at the 12th fret or where the neck meets the body. The closer you move towards the sound hole, the more bass you will get. Because of the supercardioid polar pattern, you will get less room tone from a distance than you would with a normal figure-8 ribbon microphone.
The KU4 delivers a great sound as a close-up and distant mic on upright piano. Because of its supercardioid polar pattern, the KU4 does a great job of picking up the direct sound of the instrument.
A pair of KU4s spaced 18 inches apart from each other and 24 inches away from the piano can make for a rich and lush sound. A single KU4 at the same distance, positioned above the performer’s’ head pointed slightly down at the hammers will capture a focused and direct sound.