AKG C414 B-ULS
The large-diaphragm condenser that ended up in more American studios than any other. The manual makes a pretty good case for why.
Overview
The AKG C 414 B/ULS is a dual-diaphragm, externally polarized condenser microphone built around a pair of back-to-back one-inch (25 mm) gold-sputtered capsules. AKG's own documentation calls it "the most ubiquitous studio condenser microphone in the United States, and very likely in the rest of the world as well". That reads like marketing until you look at what the mic does. It has four switchable polar patterns (omni, cardioid, hypercardioid, figure-eight), a two-position bass cut at 75 or 150 Hz with a slope steeper than 12 dB/octave, and pre-preamp attenuation of either 10 or 20 dB. The switchable pad is there to keep the mic's internal output transformer, and whatever transformer sits at the front of your console's input stage, from being slammed by close-miked sources.
The headline numbers are strong. On-axis sensitivity is 12.5 mV/Pa across all four patterns, which works out to roughly -38 dBV. Self-noise is rated at 14 dB-A, and the signal-to-noise ratio is 80 dB A-weighted. Maximum SPL for 0.5% total harmonic distortion is 134 dB wide-band in unpadded operation, or 140 dB at 1 kHz. The electrical impedance is 180 ohms, and AKG specifies a load impedance of greater than 1,000 ohms. That works with most modern preamps without a special matching transformer.
The interesting part historically is what AKG put inside it. Studio Sound (August 1989, p.37) reported that the microphone incorporates the electronics of the successful C460 preamp, developed from the earlier C414 to set a new standard in low-noise, high-efficiency studio condensers. The manual states that lineage too: the design draws on long-term worldwide experience with the C 12A, C 12B, C 414 comb, and C 414 EB-P 48. AKG redesigned the electronics with particular attention to linear transfer characteristics across every electrical parameter. The claimed dynamic range is on the order of 125 dB A-weighted, which AKG describes as substantially higher than conventional condenser microphones and associated equipment.
The frequency response is flat to a degree that borders on boring. AKG's documentation claims the far-field on-axis response varies by no more than ±2 dB from 20 Hz to 20 kHz across all four patterns. The patterns are described as highly uniform and frequency-independent, so off-axis sound keeps the same character as on-axis.
Physically, the mic is compact: 5.6 x 1.8 x 1.4 inches (141 x 45 x 35 mm), weighing 11 ounces (320 g) net. The housing is all-metal, finished in non-reflective black, and AKG notes that the metal body helps reject RF interference. The connector is a standard 3-pin XLR. Included accessories are the H 100 elastic suspension and the W 414 foam windscreen, plus an original frequency response curve with the serial number and production date code. The SA 18/3 stand adapter is optional, as are the B 18 battery supply and N 62 E power supply for situations without phantom power.
On powering, the B-ULS is forgiving. The manual specifies phantom powering per DIN 45596 - positive voltage on the audio lines versus the cable screen - nominally 12, 24, or 48 volts. AKG also states the mic will operate on any voltage between 9 and 52 volts without special adaptation. Standard resistor values for center-tapped and non-center-tapped input transformers are documented in the manual (330 ohms / 680 ohms at 12 V, 3300 / 6800 ohms at 48 V), and AKG recommends at least 0.5% tolerance resistors to maintain symmetry. For unbalanced or transformerless inputs, the manual calls for capacitors or optional transformers in the audio lines to block current leakage.
The diaphragm is a plastic foil with gold deposited on one side only. AKG's stated reason is to prevent short-circuiting to the main electrode when extremely high sound pressure levels hit the mic. The twin-diaphragm system handles pattern switching, and because the patterns are frequency-independent, the off-axis bleed in a multi-mic setup stays tonally consistent with the on-axis sound.
AKG also built a transformerless sibling, the C 414 B-TLII. It shares the B-ULS's specifications but adds a capsule modified with a rise in frequency response starting around 3 kHz to boost vocal presence, and it eliminates the limiting output transformer for cleaner high-level low-frequency transmission. The B-ULS keeps its transformer, and AKG's documentation frames that as the tradeoff: the transformer is part of what the pre-attenuation circuit is designed to protect.
The manual also documents routine maintenance: metal surfaces can be cleaned with methylated spirit or alcohol, and the foam windscreen should occasionally be soaked in a mild detergent-and-water solution and allowed to dry. A three-year warranty against defects in materials and workmanship applied to original US purchases, with the usual exclusions for abuse, unauthorized service, and transit damage.
For anyone tracking down a used example today, the practical appeal is straightforward. The B-ULS is a known quantity in studios worldwide, its manual is thorough, its accessories are documented, and its phantom-power tolerance means it will work with almost anything you plug it into. Whether that makes it the right mic for a given source is a question only the source can answer — but the B-ULS's reputation was built on being the mic that answers that question more often than most.
Similar items on eBay
No exact AKG C414 B-ULS listings are live right now — these searches show current AKG and similar vintage audio gear on eBay:
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.