Elegant and revolutionary; A modern classic.

Some of my all-time favourite recordings have been made with the AKG C12 (or it stereo counterpart C24), I always adored its distinctly refined sound and musical articulation. Unfortunately, these are quite rare and extremely expensive microphones, so acquiring one is out of the question.

Austrian Audio, formed by ex-AKG employees, promises to carry the much-desired sound of the classic AKG microphones to the 21st century, with outstanding engineering, forward-thinking features and a competitive price. Based around the new handmade ceramic capsule CKR12, and 100% manufactured in Vienna, the large-diaphragm multipattern condenser OC818 and its sibling, the fixed-cardioid OC18, create high expectations.

Brass-ring capsule issues

The brass-ring CK12 capsule, originally designed for the C12 and early C414 microphones, offers an excellent frequency response with even characteristics on- and off-axis but was so labour intensive and inconsistent that AKG dropped its production and moved on to a simpler design more than 40 years ago. Numerous successors have been presented, and as with all sought-after microphones, a lot of clones have tried to recreate the magic of the famous capsule. But, in the hearts of the audio engineers, the original C12s and C414s, when in good condition, are still the best sounding.

Austrian Audio measured some of the best sounding CK12 capsules available to model the CKR12 which is at the heart of every OC18 and OC818 microphone. The new capsule is ceramic and is made by hand, this design should have a similar response but with greater consistency and durability.

Classy looks

The microphones themselves look rather classy and somewhat understated with a body made of a single piece of zinc-aluminium alloy, finish and craftsmanship are impeccable. The OC818 is silver, while the OC18 is black and lacks the polar pattern selector switch and the second output on the back, but is otherwise identical. The silver finish of the OC818 looks slightly more elegant, but with one drawback; the lettering on the switches is a little to see under certain lighting conditions.

Polar pattern selector, filters and pads on the OC818.

There are 40Hz and 80Hz high-pass filters at 12dB/octave available to control low-end rumble as well as a gentler 6dB/octave at 160Hz to compensate for proximity effect. Carefully chosen high pass filters on microphones and preamps are appreciated here as it is preferable to cut unwanted frequencies before they hit the digital realm. When recording classical guitar, I pretty much have the 40Hz filter engaged at all times.

The sensitivity of 13mV/Pa is respectable, making the choice of preamp less critical. Both the OC18 and OC818 worked flawlessly with the preamps of an RME Babyface Pro FS and my AEA TRP2 external preamps. Both microphones also incorporate -10dB and -20dB pads to protect the internal electronics from very loud sources, which is never a problem with classical guitar, so I haven't tried them. On the other hand, the self-noise of 9dB-A is superb for capturing the subtle plucking sound of nylon strings, especially for very dynamic playing styles.

Dual-output capabilities

A Mini-XLR gives a separate output from the rear capsule of the OC818.

A distinctive feature of the OC818 is the ability to record the two capsules separately and blend them later during mixing with the PolarDesigner plugin to craft the perfect polar pattern. Read my post regarding the PolarDesigner plugin here. Or use the OCR8 Bluetooth dongle and choose between 255 discrete polar patterns in realtime. Unfortunately, I wasn't provided with the OCR8 to test that feature, but the PolarDesigner plugin has been excellent.

Finally, a new plugin developed by Austrian Audio called AmbiCreator makes possible the recording of ambisonic B-format signal with two OC818 microphones. I haven't tried that yet, but I like that the team of Austrian Audio is restless.

Accessories

A pair of OC818s and a single OC18 in the aluminium case.

Austrian Audio was kind enough to send me a pair of OC818s and one OC18 for testing, the microphones arrived in a compact aluminium case which is excellent for storing and transferring them. Wooden cases can sometimes be more luxurious, but an aluminium case is lighter and much more practical. I was also provided with shock-mounts and simple plastic clip mounts. The shock-mounts are compact enough and seem to work well. Saying that, I would like to see them design a more elegant mount as an alternative to match the sophistication of the microphones.

So, how do they sound?

I first tried the microphones with the Cardioid pattern and my usual wide AB setup. The OC818s captured the articulate character of my spruce/brazilian rosewood classical guitar in abundance. Paired with my AEA TRP2 preamps and RME ADI-2 Pro FS converters, the OC818 pair delivers a gorgeous rich sound with excellent clarity. The tone is bright and defined but in a smooth way, not peaky or harsh neither hyper-realistic.

Austrian Audio OC818 in Cardioid & OC18 - Frequency Response and Polar Pattern

When tested against the Neumann TLM 193, an honest and natural microphone, it becomes apparent that the Neumann is somewhat subdued on the high-mids. And while both microphones can produce a beautiful recording, I prefer the more detailed sound of the OC18 and OC818. I've been using the Neumann TLM 193 for years so their somewhat laid back nature is not new to me, and therefore I usually chose to pair it with a brighter mic, like the TLM 102/103 for instance, to bring back some articulation.

I also tried the OC18 against the Neumann TLM 102, a microphone that I always liked for its natural response, I found that in comparison the Austrian Audio offers a richer midrange with more fluent top-end and defined low-end, thus making the Neumann sound a little hollow in the mids. Arguably, the OC18 is the better microphone, and not much more expensive.

Another microphone I had available for testing is the Gefell UMT70s, a multipattern large-diaphragm condenser built around the famous Georg Neumann M7 capsule and with the finest engineering. It appears to me though that the Cardioid and Figure-8 patterns of the UMT70s were voiced for close miking, and found them to be less desirable for solo classical guitar which benefits from more distant miking. I would imagine that up-close, the Gefell would produce juicy recordings for popular musical styles.

Austrian Audio OC818 in Omni - Frequency Response and Polar Pattern

Both the Gefell and Austrian Audio microphones sounded outstanding in Omni, albeit with a different character. The OC818 produce a more natural, true-to-life recording of the guitar in the room with even response across all frequencies and a fuller low-end, the frequency response graph shows a slightly more pronounced high-end with more gentle high-mids. The Gefell UMT70s in Omni imposes a smooth and creamy sound; juicy and delicious, but not nearly as accurate. Honestly, if I only needed an Omni microphone, I would be happy with either. The OC818 costs less though and sounds consistently excellent in all patterns.

A universal studio microphone

Austrian Audio OC818 in Hypercardioid - Frequency Response and Polar Pattern

I then switched to the Hypercardioid pattern and a slightly more distant set-up. The tighter pattern leaves most of the room out of the recording and the extra distance lets the guitar breath more freely. There is a little less body to the guitar sound but mids and highs are captured in detail and elegance; for challenging rooms, one or two OC818s in Hypercardioid would be the best choice.

For placing the classical guitar inside a denser mix, the tight pattern, and the absence of room ambience of the Hypercardioid pattern offer a vital asset. My instinct when laying down the guitar part for an Elusive Aura recording last July was to use the Omni pattern of the OC818. I couldn’t get the mix right though; the room sound pushed the classical guitar in the background, and in the low strings were fighting with the two cellos. I decided to re-record my part with the Hypercardioid pattern and voila! The classical guitar part almost mixed itself.

Finally, I tried a pair of OC818s in an M/S setup with a Cardioid Mid microphone, read my Three M/S Setups for Classical Guitar post. The truly symmetrical Figure-eight pattern and the full low-end extension should make the Austrian Audio microphones excellent in that application. After processing the Side microphone and balancing the levels, the result is a very realistic image of the guitar with a solid centre image and a polished sheen. My room, even though it's not large, it has a pleasant sound for acoustic instruments due to non-parallel walls, high ceiling, wooden floor and moderate treatment. I can imagine that the OC818s in M/S would sound impressive in a large hall or church.

Austrian Audio OC818 in Figure-eight - Frequency Response and Polar Pattern

Ambience duties

In this Bach's Cello Prelude recording, I used a distant pair of OC818s in Cardioid to pick up the room together with the Neumann TLM 193 and AEA N8 in M/S Stereo placed in the direct field. I think that the Austrian Audio captured the ambience admirably and provided the recording with detail and clarity. In that scenario, the laid back character of the Neumann and AEA combo complements perfectly the brilliance of the Austrian Audio pair.

OC18 vs OC818

I believe it is a smart move for Austrian Audio to release the fixed-cardioid OC18, as many don't need the extra patterns and can save a few hundred euros. According to Austrian Audio, the tolerances of the CKR12 capsules are so tight that any OC18 and OC818 will perfectly match and can be even used as a stereo pair. But, given how much more versatile the OC818 is, costing only (at least for the time) a few hundred more, it is difficult to recommend the fixed-cardioid version.

Conclusions

Austrian Audio are the rightful heirs to the CK12 design tradition, it doesn't surprise me in the least that they developed a new microphone that sounds so alluring. Contrary to a lot of large-diaphragm condensers that either produce a fake sense of clarity with over-pronounced high-end or a smeared response, the Austrian Audio microphones capture ample detail; yet they manage to remain smooth, never harsh or sharp.

With low self-noise, exciting yet clear sound and dual output, the OC818 has become my favourite large-diaphragm condenser for recording the classical guitar. I used the pair of OC818s in Omni for the recordings of my latest classical guitar suites "A Quiet Place" pt. I and II, and with a custom polar pattern on “Baltik Winter”.

Coda A - Apples vs Oranges

I compared the OC818 with DPA's 4006A and 4011A small-diaphragm condensers. The DPA could be my favourite sounding microphones for classical guitar; their truthfulness is unsurpassable but they suffer from a relatively high self-noise, especially the 4011A. The omni 4006A has an impressive 40 mV/Pa sensitivity and is less noisy.

This may seem like comparing apples and oranges due to the different design, but the DPA microphones are the epitome of clarity, definition and precision and I wanted to see how the Austrian Audio microphones compare. Both DPA capsules offer an almost brutally honest pick-up, with breathtaking realism; like “being there in the room”. To my surprise, the OC818 set in Omni and Cardioid respectively comes quite close; maybe not as realistic and precise, but a touch more musical and seductive in exchange.

The OC818 is a large-diaphragm condenser and might not be best suited as the main pair for orchestral recordings. On the other hand, for small ensembles and solo instruments, the noiseless operation and extra musicality can be favourable.

Coda B - Perfect for the Cello

My friend and great cellist Natasha Jaffe came over to my studio one day and we tried one OC818 in front of her Cello. We immediately loved the expressive and balanced sound the microphone captured, the Neumann TLM 193 seemed a little dull in comparison. We tried a couple of different positions to make sure that no microphone had an advantage, the results were consistent across all tests. Natasha decided to buy an OC818 for her own productions, as she felt that the sound of the Austrian Audio was "finished" and “ready”.

Coda C - Recording Debussy

Here another is a real-world example of the use of AB Stereo on Classical Guitar in a professional setting. I used a pair of Austrian Audio OC818 microphones set in a Custom Polar Pattern that combines the best of Cardioid and Omni qualities. The spacing of the microphones is 26cm. The goal was to capture the pure tone of my Angela Walter guitar together with the incredible sounding main hall of the Musikbrauerei in Berlin.

Austrian Audio