Microphone Masterclass: AKG C12

Our LD-12 model – and the two specific mics in the Ocean Way Collection,  the OW-12 #1 and #2 – are based on the AKG C12, a legendary mic from the 1950s whose unparalleled sound arose from its unique combination of capsule design and tube electronics. In this Microphone Masterclass, meet the mic that, for many, is the holy grail of condenser mics.

Microphone Masterclass: AKG C12 full HD 16x9 thumbnail

There is no microphone in the world quite like the AKG C12. Manufactured by AKG from 1953 to 1963 (and originally designated “C 12” using AKG’s numbering system), it is considered by many to be the ultimate multi-pattern large-diaphragm tube condenser mic. Even compared to other supposedly unattainable vintage classics like the Neumann U 47, the C12 is fabulously rare. It is believed that fewer than 2500 were made during the mic’s original production run, and it is unknown how many remain functional today. At the same time, engineers and producers around the globe continue to rave about the C12 for vocals, drums, brass instruments, and string sections, just to name a few applications.

"It's an extremely open and airy-sounding microphone. It's my standard overhead left/right drum mic." - Allen Sides (Joni Mitchell, Celine Dion, Phil Collins, Supertramp)

What made the C12 so special? While it’s easy to wave a hand and say, “Any mic that is that old has a certain mystique,” the truth goes deeper. For a better understanding of why the C12 has never been equaled, much less surpassed – even by AKG – it’s good to know a little bit of history.

The beginning of the beginning

In a modern world of affordable, accessible mics at all price points, we are constantly reminded of the glory days of vintage microphones… mainly by the makers of inexpensive ‘clones’ who would like us to believe that they offer the same magic at a fraction of the price.

However, young engineers need to understand that there was a time when every new microphone was a journey into uncharted lands. The process of mic design was one of handmade prototypes, of painstakingly tweaked subsystems, carefully-selected parts, and a constant process of refinement unaided by anything fancier than a slide rule, pencil and paper, and keen ears. We never hear about the hundreds of false starts that ended up in the trash, but we remember the successes, and the C12 was one of the very first.

On paper, the C12 was a conventional enough design by modern standards: a dual-diaphragm condenser capsule mated to a dual triode tube head amplifier and mounted in a side-address housing. That said, each element of the mic was classic in its own right.

Microphone Masterclass: AKG C12 close up shot

The iconic shape and design details of the AKG C12 made it an instant classic that has easily passed the test of time.

Design Choices

The capsule developed for this mic was known as the CK 12. It was a hand-tensioned, edge-terminated design that became the parent of many famous capsule designs to follow. This was a dual-diaphragm/dual-backplate design that allowed for multiple polar patterns based on altering the voltage to one diaphragm with respect to the other.

The amplifier circuit was based around the General Electric 6072 dual-triode vacuum tube and was transformer-coupled at the output. Part of the C12’s mystique came from the fact that the 6072 was never a commonly available tube to begin with, and is now quite rare.

The C12 offered nine different polar patterns, from omni through cardioid to figure-8. In the original design, polar patterns could be remotely selected, a design choice seen only once before in history (in the slightly older Neumann M 49). Instead of a pattern selector on the supply itself, the C12 had a remote control box connected to the power supply by its own long cable. This had the benefit of pattern selection free of clicks and pops, and was a boon to mics permanently installed in hard-to-reach places – aloft in concert halls or soundstages, for example.

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There was no single “C12 sound” because AKG’s engineers constantly refined the design throughout its lifespan. While the output transformer and sometimes the tube were changed out, most of these changes were made to the CK 12, which was updated for reasons ranging from improved sonics to easier manufacture. 

Obvious changes were in construction materials: different plastics under the gold sputtering, different tensioning rings (from brass to two kinds of Teflon). There were other changes, too – spacing between the backplates changed over the years to create better sensitivity, for example, and less controlled variations from processes like tensioning and sputtering that weren’t tightly regulated from mic to mic.

These variations in the CK 12 produced many further variations through the following decades as various makers chose different design variants to imitate. One famous example is a classic mic in its own right: the Telefunken Ela M 251, which was in many ways just a simplified C12 with fewer polar patterns (selected on the body), a slightly simpler head amp, and perhaps most importantly, a differently shaped case and grille, which had a significant effect on the overall sound of the mic.

THAT Sound

The C12 was the first example of what we now think of as the vintage AKG signature sound. The capsule response, electronics, and resonant properties of the case and grille combined to create a beautiful frequency response curve – mostly flat, with a broad presence peak centered on roughly 10 kHz, and a tiny scoop around 2 kHz at certain polar pattern settings. If any one element of the combination was tweaked, the response would become audibly different – this is what happened with the Ela M 251. The mic had a reasonably low self-noise and wonderfully clear high end that wasn’t too harsh, making it a perfect choice for everything from bass amplifiers (Paul McCartney loved it) to full orchestra sessions.

The place where the C12 truly shone, however, was on vocals. Hundreds of hit records from the 1950s to the present day were cut with the lead and backing vocals captured by the C12. It has an almost ethereal quality when handling softer vocals, yet it easily handles the loudest belting with aplomb. This is where the LD-12 model will truly shine in sessions using the Sphere L22!

The LD-12 is modeled after a mic owned by Hyde Street Studios in San Francisco. It’s Serial Number 1911, a fairly late build (circa 1960) with most of the refinements of later C12s in place. Have a listen to our range of microphone models based on AKC C12s below.

The Ocean Way Collection mics

Townsend Labs’ LD-12 is not the only C12 model available for the Sphere L22. The Ocean Way Collection from Universal Audio (for the UAD and Apollo DSP engines) adds specific models of two specific C12 mics from the 1950s, borrowed from the impressive mic locker at Ocean Way Studios in Hollywood.

OW-12 #1 uses SN 1188, which has a bit more of the classic 10 kHz bump, and OW-12 #2 uses SN 1175, which is one of the warmest and smoothest C12s in history – the mic used to record Frank Sinatra on LA Is My Lady.

Check out this video interview with the former Ocean Way Studios owner, famed engineer, and mic aficionado Allen Sides. Allen curated the mics that we modeled for the Ocean Way Collection.

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Have a look at the frequency response curves of our three mic models based on the AKG C12. As you can see, the top end varies quite considerably on these vintage microphones.

Continue your AKG C12 microphone masterclass on Audio Test Kitchen

We've partnered up with our friends at Audio Test Kitchen so you can hear our C12 models in action. Select source material for different instruments and for several genres. You can even get the "stacked effect" to find out what an entire track recorded with one mic would sound like!  Audition and compare the three currently available C12 options, and find out which one you like best.

Science Meets Art To Make Magic

The LD-12 model can be combined with the many adjustments possible in the Sphere plug-in to create acoustic properties never dreamed of by the AKG engineers of 60+ years ago, all while retaining some of the essential atmospheric quality of the original C12. Because it’s very forgiving of sibilance, the LD-12 is excellent for vocals with a lot of high-end content, retaining presence, and just a bit of sparkle without becoming spitty or hashy. This in turn requires less post-processing with EQ, which leads to a clearer and more honest-sounding vocal track.

If you have two Sphere L22 mics, try the LD-12 in a Mid/Side arrangement with your choice of cardioid-pattern models, or in a Blumlein array for a room-friendly stereo capture. 

Every model that comes with the Sphere L22 has something unique to offer the modern engineer, whether in a small personal studio or a multi-room professional facility. That said, the LD-12, like its vintage forebear, has a magic that’s hard to quantify but easy to love. We hope you've enjoyed this microphone masterclass about the AKG C12. Stay tuned for more episodes very soon.

With Sphere you now can:

  • Record with the sound of microphones many have only dreamt about
  • Change mic type, polar pattern, and other microphone characteristics, even after tracking!
  • Audition the sound of different microphones without tiring the vocalist
  • Reduce bleed, undesirable room coloration, and other common issues using Off-Axis Correction™
  • Record in stereo from a single microphone

You are invited to install the free, fully-featured Sphere plug-in for all major platforms and DAWs. Try it now and reimagine our library of pre-recorded tracks.

Unless otherwise noted, all brand and product names referred to in this article are trademarks of their respective owners, which are in no way associated or affiliated with Townsend Labs.