AKG C 414B
A dual-diaphragm studio condenser that became the default answer to "which mic?" in more rooms than anyone can count.
Overview
The C 414B is built around a pair of back-to-back one-inch (25 mm) gold-sputtered diaphragms. That one design decision explains most of what the mic can do. Four polar patterns - omnidirectional, cardioid, hypercardioid, and figure-eight - are selectable from a recessed switch on the front of the body, so one microphone covers the ground that would otherwise take four. AKG's own documentation says the C 414 B/ULS combines four different microphones in one housing. The patterns are held uniform and frequency-independent, so the off-axis character stays consistent as you rotate the mic.
AKG's manual traces the design directly to experience gained in long-term worldwide studio operation of the C 12A, C 12B, C 414 comb, and C 414 EB-P 48. The diaphragm is a gold-flashed plastic foil. The gold layer is deposited on the outer side only, which the documentation calls a deliberate choice to prevent short-circuiting to the main electrode when extremely high sound pressure levels hit the capsule. That is the kind of detail you only engineer after watching a design fail in the field.
Sensitivity is 12.5 mV/Pa (equivalent to -38 dBV) across all patterns. The far-field on-axis response is specified as varying no more than ±2 dB from 20 Hz to 20 kHz. Owners who have put these against measurement rigs tend to treat that figure as honest rather than aspirational. Self-noise is rated at 14 dB-A, and the signal-to-noise ratio is 80 dB A-weighted. AKG's own literature puts the resulting dynamic range around 125 dB, which the manual points out is substantially higher than what conventional condensers and their associated gear typically manage.
Maximum SPL is where the spec sheet gets interesting, because it depends on which number you read. AKG lists 134 dB wide-band unpadded for 0.5% THD, and 140 dB at 1 kHz unpadded for the same distortion threshold. The architects-and-engineers specification in the same documentation settles on the 140 dB figure for wide-band operation with no more than 0.5% total harmonic distortion. Collectors comparing notes should treat the 134 dB wide-band number as the more conservative real-world ceiling and the 140 dB as the 1 kHz figure. Both appear in AKG's own materials.
Two switchable filters handle the practical problems. A bass cut rolls off at more than 12 dB per octave, with a corner frequency selectable at 75 Hz or 150 Hz. It helps against wind noise, stage floor rumble, and the low-frequency garbage that creeps into close-miked sources. A preattenuation switch drops sensitivity by 10 or 20 dB. That raises the undistorted maximum SPL accordingly and keeps small output transformers in the mic and at the console input from being pushed past their limits on loud sources.
The C 414B name covers more than one microphone, so the variants need sorting out. The C 414 B-ULS is the transformer-equipped version, and AKG describes it as one of the most accurate multi-pattern microphones available to the engineer. For engineers who wanted the transformer out of the signal path, AKG built the C 414 B-TLII. It is transformerless, with a modified capsule that adds a rise in frequency response starting around 3 kHz to boost the presence range of a vocalist's voice. The TLII meets all the other C 414 B-ULS parameters, and with no limiting output transformer it passes very low frequencies at high level with low distortion. Two different tools, same badge.
Powering is flexible. The microphone runs on phantom power per DIN 45596. The standard specifies 12, 24, or 48 volts, but AKG's documentation states the C 414 B-ULS will operate on anything between 9 and 52 volts without adaptation. That tolerance has kept a lot of these microphones working in rooms with non-standard or tired phantom supplies. The connector is a standard 3-pin XLR. The electronics are specified at 180 ohms impedance with a recommended load of greater than 1,000 ohms.
The housing is all-metal, which AKG notes adds rejection of RF interference when the mic is used near transmitter stations or alongside wireless gear. That is a real concern in broadcast and live work. Finish is non-reflective black. The body measures 141 x 45 x 35 mm and weighs 320 grams net, 950 grams shipping. Included accessories are the H 100 elastic suspension and the W 414 foam windscreen, with an original frequency response curve bearing the serial number and production date code. The SA 18/3 stand adapter is optional and uses a standard 3/8-inch threaded insert. It detaches by rotating 90 degrees against the mic's main axis and pulling downward. A small rim on the shaft prevents accidental drops even when the fastening lever is loose.
Independent period coverage in Mix (June 1988, p.46) called the C 414 line an industry standard, "everybody's mic," and argued that the shift toward digital recording, 16-bit processors, and CD-era demands was raising the bar for microphone performance. It shows how the C 414B was received in its working years: not a boutique choice, but the mic that showed up on session after session.
By 2004, the picture had shifted to the XLS and XL II versions. Mix (September 2004, p.130) noted that AKG had been upgrading and optimizing the C 414's specs and feature set since the original C 414 Comb's 1971 debut, whenever better components and manufacturing techniques became available. That same coverage described the newer generation's accessory package: a square foam windscreen, an external metal goosenecked two-stage pop filter that mounts to any stand or boom, a dust cover, an individual frequency plot, and a multilingual manual. A stereo kit bundled two sets of the same. EQ (August 2004, p.72) listed the C414B-ULS at $999 and the C414B-XL II at $1,099 at that point, and noted the X generation represented the first changes to the model since 1993, with a lineage, as the same magazine put it, that runs long.
That 1993 date is the useful anchor for anyone trying to place a used C 414B-ULS or B-TLII. The "B" designation and the ULS/TLII split belong to the era before the X-series redesign. The documentation AKG shipped with these microphones is unusually specific about service procedure. The manual warns that if the mainboard is replaced, the high-impedance board must be exchanged with it, and AKG ships them together as a spare-part pair, because the resulting sensitivity can vary substantially from the original value. The same document recommends sending microphones to AKG for repair when capsule-adjacent parts are involved. It states flatly that if one of the stranded wires to the capsule breaks, it should not be re-soldered but replaced. Cleaning guidance is simple: metal surfaces take methylated spirit or alcohol, and the foam windscreen can be soaked in a mild detergent solution and dried.
The documentation gives a practical checklist for buying used. Confirm which version you are looking at, ULS or TLII, because the capsule voicing differs above 3 kHz. Check that the pattern switch, pad, and filter all engage cleanly. The pattern selector is recessed into the front of the body and is the part most likely to have seen hard use. Verify the capsule wires have not been field-repaired, since AKG's own guidance says a broken one should be replaced rather than re-soldered. Confirm the H 100 suspension and W 414 windscreen are present if you care about completeness. They were included originally and are the accessories most often lost.
The C 414B is a large-diaphragm condenser with a documented ±2 dB response spread across the audible band, 14 dB-A self-noise, a 125 dB dynamic range, and four patterns that behave consistently off-axis. AKG gave it an all-metal housing to keep RF out.
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