AKG C 410
A 30-gram condenser that hides behind your neck and puts a cardioid capsule at the corner of your mouth.
Overview
The C 410 is a headset-type miniature condenser microphone built around a behind-the-neck headband. AKG's own manual is blunt about the intent: the mic hangs off a headband, the capsule is cardioid, and it prefers the sound coming from in front of it - your voice. At 30 g without the connector, it's easy to forget you're wearing it.
The capsule is a prepolarized condenser transducer. Frequency range is quoted at 20-20,000 Hz. Sensitivity at 1000 Hz is 3 mV/Pa (that's -30 dBV re 1 V/Pa), and electrical impedance at 1000 Hz is 600 ohms, electronically balanced. Maximum SPL for 1% T.H.D. is 123 dB SPL, and the equivalent noise level is 34 dB to DIN 45412. Recommended load impedance is ≥ 1000 ohms. Powering is universal phantom, 9 to 52 V per DIN 45596, drawing approximately 2.2 mA. That 34 dB equivalent noise figure is the honest number in the spec sheet. This is a stage and broadcast tool, not a whisper-quiet studio capture mic, and AKG never pretended otherwise.
The construction is more interesting than the spec block suggests. The essential parts are made of a high-strength plastic (Hostaform), and the microphone case is Noryl. The condenser transducer sits in that Noryl housing, shock-mounted to the microphone arm to keep cable and vibration noise - structure-borne sound - out of the capsule. The arm geometry is deliberate: it's sized so the mic lands near the corner of your mouth rather than dead center, which dodges pop noise and keeps the capsule away from the worst of the contamination. A detachable foam wind and pop screen (the W 410) ships with it, and there's a cable clip in the box.
The C 410 came in four versions, and this is where buyers get tripped up. The standard C 410 is phantom powered, with a 3.5 m cable terminating in an XLR connector that houses the phantom adapter and balancing electronics. The C 410/B9 is the battery-powered version, with a 1.5 m cable, a 3.5-mm mono jack plug, 20 mV/Pa sensitivity, and a 200-ohm unbalanced output. That's a substantially different electrical animal from the standard model. The C 410 WL/1 has a 1.4 m cable and a 4-pin miniature connector for the PT 42 pocket transmitter. The C 410 WL/2 has a 1.4 m cable and a 6-pin connector for the T 85 and T 185 handheld transmitters via the optional A 85 adapter. Pinouts differ across all four, and the manual spells each one out. The standard C 410 uses pin 1 ground, pin 2 in-phase hot, pin 3 out-of-phase cold. The WL/2 assigns pins 1-3 as unused, pin 4 audio in-phase, pin 5 ground, pin 6 supply current. Anyone buying used should confirm which variant they're getting before wiring anything up.
If your mixer has no phantom power, the C 410/B9 needs no extra supply unit at all. The standard phantom C 410 can alternatively be fed from a B 18, N 62, or N 66 supply unit. For unbalanced mono jack inputs on a mixer or tape recorder, the manual gives a wiring workaround: bridge pins 1 and 3 in the XLR connector to the shield, and connect pin 2 to the tip of the jack plug. The WL/1 draws its power from the PT 42 transmitter battery and plugs into that unit's 4-socket input. Sensitivity adjustment follows the transmitter's own manual.
AKG's B 9 battery supply unit goes with the battery version. It delivers 9-V phantom power (from a 6F229-V battery) to the C 410/B and lets it work with mixers and recorders that have no phantom power of their own. It has two 3.5-mm jack inputs so it can power two microphones at once, with a balance control to compensate for level differences between them - say, between a voice and an instrument - plus a master volume control. Output is a 1/4-inch mono jack socket that switches the B 9 on when a plug is inserted and off when it's pulled. AKG's manual is explicit that the battery lasts longer if you disconnect the output cable after each gig, session, or rehearsal, and there's a metal belt clip on the rear. The B 9 will also power AKG "MicroMic" series mics: the C 401/B Pickup, C 402/B, C 408/B, and C 409/B.
Period advertising leaned hard on the C 410's on-camera manners. AKG's own copy, as it ran in Mix (November 1987, p.41), pitched the headset mic alongside the D 112 kick drum mic as the answer to lens flare and burnout on-camera - no smudgy fingerprints in closeups, no fighting the crowd for attention. The same campaign copy appeared in Recording Engineer (August 1987, p.37) and Sound and Communication (October 1987, p.17). Treat those as marketing claims, not measurements. A later Sound and Communication roundup (September 1988, p.33) lists the C 410 among microphones in its survey pages, and a db Magazine (July 1990, p.52) model table carries AKG condenser entries alongside the C414. The OCR on those tabular pages is rough enough that specific C 410 figures shouldn't be read off them.
Environmentally, the mic is rated for -10°C to +60°C and 90% relative humidity at +20°C. The capsule itself measures 11 mm diameter by 16 mm. Finish is matte black.
Collectors and working engineers tend to seek these out for two reasons: the headset format is hard to replace in period-correct broadcast kits, and the variants make it a small puzzle to assemble correctly. The practical failure points are the ones you'd expect from a 30-gram plastic-bodied headset - cable strain at the connector, the foam windscreen degrading, and battery supply units going missing or corroding. Original accessories (W 410 windscreen, cable clip, B 9, A 85 adapter) are frequently separated from the mic by the time it reaches a second owner, so a complete example with its supply hardware commands more attention than a bare capsule. Confirm the exact version before purchase. The /B9 and WL variants use different connectors and different output characteristics, and swapping them without the matching transmitter or adapter leaves you with a mic you can't plug into anything.
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