A Three-Microphone Setup for Recording Classical Guitar
An M/S Stereo alternative.
Classical Guitar is a complex and rich sounding instrument; as such, it sounds better when is recorded with at least two microphones. A statement that you must have read several times already if you hang out at this site. Some engineers argue though that guitar is a relatively small instrument which tends to sound too "wide" when recorded with the most conventional stereo techniques; thus sounding unrealistic in playback.
Neumann TLM 193 and TLM 170 in M/S Stereo Configuration
Mid/Side stereo, which I discuss in my Three M/S Stereo Setups for the Classical Guitar article, is usually praised for its truthful representation of the classical guitar. The elimination of phasing problems and the flexibility it offers during mixing are additional important advantages, however, it is not immune to potential issues. Namely, the collapse of the room information in mono reproduction, and the inability to hear the resulted-combined sound without some processing to the channels (or the use of an M/S matrix). Lastly, symmetrical Figure-8 microphones, required for the "Side" channels, with a balanced response are generally expensive.
Alternatively, the combination of a "Mono" microphone placed at close-proximity and a "Stereo Pair" at some distance, shares some similar advantages without the drawbacks of M/S Stereo. Hence the Three-Microphone Setup is an appropriate option for capturing the subtleties of the classical guitar.
Purpose in position
Austrian Audio OC18 - A Large Diaphragm Cardioid Condenser
The "Mono" microphone is positioned close to the instrument (at about 50cm, although some could go as close as 30cm) to capture a full-bodied sound. I recommend a large-diaphragm condenser with a smooth treble response for this position; as not only it will capture the fullest sound, but the slower transient response of the large capsule will also give a less analytic, more relaxed response.
The "Stereo Pair" is placed a little further away to capture the sound of the room. A pair of small-diaphragm condensers is ideal here due to the better off-axis response and can be either Omni or Cardioid patterns depending on the acoustics. The actual distance depends mainly on the room; accordingly, as the distance increases, the height of the microphones should be increased as well. The distant pair brings to the mix crucial depth, space and some high-end articulation.
Decisions; Player vs Audience
Another way to see the three-microphone setup is as a fine compromise between the intimacy of what the player hears and the somewhat distant experience of an audience member.
During mixing, the three channels can be balanced to the desired sound; from close to distant and everything in between. Either the "mono" or the "stereo pair" can be used as the base sound. Think about a mono capture with some extra space or a distant pair with added fulness.
Examples
For the first recording, I used a Neumann TLM 193 relatively close to the guitar, and a wide pair of DPA 4011As as room microphones.
In isolation, neither the Mono signal nor the AB pair sounds particularly great. The first is somewhat plain and too direct, while body and weight are missing from the AB pair. When mixing all three microphones, the combined sound gets defined and three-dimensional; thus more real.
I made another example of the same setup and the exact same distances, this time with an Austrian Audio OC818 in Cardioid for the Mono duties. The AB pair is still the DPA 4011A. If you have read my Austrian Audio OC818 review, you already know that I love their sound, and I wanted to hear how well they can mix with the DPA microphones.
Combining M/S and Room Microphones
A few months ago, I also experimented with combining an M/S pair of Neumann TLM 193 and AEA N8 up close and a stereo pair of Austrian Audio OC818s at some distance, you can hear the result in this recording of Bach's Cello Prelude no.2.
Some things to take care of
If you want to try the Three-microphone setup, it is important to listen to the recording as a whole before committing to any microphone position. The Mono microphone may be judged alone if you plan to use for the main sound, but don't make bold decisions without listening to the combined audio.
Potential phasing nightmares is one of the biggest drawbacks of this setup, so take extra care to eliminate any issue and check with a proper phase meter plugin regularly (read my article on the Three Most Essential Plugins for Classical Guitar).
Lastly, although the recording should be evaluated as a whole, the close and distant setups might need to be EQed separately. Nevertheless, you may apply a catholic EQ with basic filters and sculpturing.
Cheaper Alternatives
Line Audio CM3 - A budget SDC with an surprisingly good sound
Apart from the aforementioned combinations, any microphone could do a decent job. If you just starting and your budget is limited, buy the best large-diaphragm condenser you can afford and a pair of cheaper small-diaphragm condensers, like the Line Audio CM3/CM4 (read my comparison of the Line Audio CM3 and DPA 4011A).
Final thoughts
I've seen mostly AB, XY, ORTF and sometimes M/S setups explored by engineers and home recordists for the classical guitar. All of which can produce excellent recordings given the right circumstances. Yet, I find that with more elaborate techniques I can capture the instrument, at home or on location, with exceptional precision, without any disadvantages. Except maybe for needing more input channels, cables, stands, and more time for the setup.
A Three-Microphone setup can shine in a very wet hall, as it allows us to capture the body and definition of the instrument while including as much ambience as desired. In a home recording of the classical guitar, it offers great flexibility, if not to provide ambience, it combines the intimacy and fullness of a close pick-up with some extra depth provided by the spaced pair.
So, what do you think? Have you tried a three-microphone setup? Which microphones have you used?
AEA N8 and KU5A Ribbon Microphones on a Classical Guitar
AEA N8 Nuvo Closeup
Ribbon microphones have a very long history, invented in the early 1920s by Telefunken in Germany, and have been used in countless historical recordings of all genres. An ultra-thin ridged aluminium (usually but not only) ribbon is placed between the poles of a magnet that translates vibrations (sound) to voltage.
Recordings made with Ribbon microphones sound very natural, have a full low-end, smooth mids and attenuated highs. They are never over-analytic if anything, they offer a relaxed presentation, making them excellent for instruments which mechanical sounds, like fretting or bowing, can be distracting. Furthermore, their pure characteristics and the bi-polar pattern generate a feeling of "being there" in the room with the musicians.
Ribbon microphones can be quite fragile and require a lot of attention even on how you store them; additionally, being passive they need a lot of very clean gain from the preamps otherwise the can appear noisy, especially with soft instruments and dynamic styles. The advances in HiFi recordings and playback systems, and their inherent downsides pushed Ribbon microphones out of fashion for several decades.
The last decades the trend seems to have shifted, at least partially. Musicians and engineers lust for the added warmth that Ribbon microphones exhibit naturally, and digital environments sometimes lack. For more than 20 years, AEA has dedicated its resources in developing and manufacturing high-quality Ribbon microphones that enable the listener to experience recordings as if he is in the same room with the musicians, and with the recent products, they hope to eliminate some of the inherent issues of this technology.
Nuvo N8 - Active Ribbon with an Extended Top-end
AEA Nuvo N8
Derived from the very well received and fantastic R88, the N8 is a mono version of the former with an added active circuit, meaning that it requires +48 phantom power to function and in exchange, it provides a higher output, making it less dependent on the preamp, and subsequently delivering cleaner recordings. The AEA TRP2 stereo preamp that I use, is specially designed for the AEA Ribbon microphones, and with its extremely clean hi-gain performance and high-impedance, it should deliver stunning recordings.
AEA designed the N8 to be used as in far-field applications, thus making it a better match for acoustic and classical recordings. And in contrast to vintage ribbon microphones, which can sometimes sound dark and murky, the N8, and the R88, capture plenty of high-end and present a controlled low-end.
Unfortunately, KMR Audio (AEA's European distributor) couldn't provide me with a pair to test some of the stereo arrays, like Blumlein or M/S Blumlein that Figure-8 Microphones excel, but I'm excited nevertheless.
KU5A - A Super-Cardioid Ribbon
AEA KU5A
The KU5A is a rather unique design in the world of Ribbon microphones, as not many non-bipolar Ribbons exist, and even less Super-Cardioid. The bi-directionality of most Ribbon microphones can sometimes be more of a burden than a blessing when used in smaller-unattractive sounding rooms. The KUA5 is a front address Super-Cardioid, that eliminates the room and presents the ribbon smoothness and warmth in all its glory, with the benefit of a detailed, extended top.
A high-pass filter of 6dB per Octave at 283Hz makes the AEA Super-Cardioid suitable for close-miking any instrument and the transformer-based, active electronics allow it to function perfectly with any decent preamplifier.
The attributes of the KUA5 make it a perfect choice for concert applications, both for amplifying the classical guitar along with recording purposes. Notably, if you play in an ensemble, The Super-Cardioid pattern will minimise the bleed from other instruments into your amplified sound. Ribbon microphones are also more forgiving than condensers, which can be a huge advantage in live recordings.
Lastly, A common issue with live acoustic recordings is that the Audience can sometimes be as loud as the instruments, the KUA5 will make sure that less of these distractions will find their way to your recordings.
Other Things
AEA KU5A Flight Case
AEA attaches the cables to the microphone on some of their products, and the KU5A is one of them, I'm not sure what to feel about this "feature" as it is nice to have, but makes the transportation awkward. The microphone itself is very well made, the built-it yoke is very sturdy and makes positioning very easy, and the is shipped in a very durable flight case. For concerts or location work, the flight case is undesirably big for the sole reason that it has to have space for the long cable.
N8 Case with Mount and Sock
The N8 is shipped with a durable plastic case which is very convenient for location recordings and for storing the microphone, a shock-like fabric cover to protect the microphone from dust, and a rubber mount that takes the place of a more regular spider mount and takes care of the low-end rumble and vibrations. The small size and weight of the N8 is also worth noting, as well as the standard XLR output, granting easy transportation and effortless positioning.
Conclusions
With active electronics for fewer noise-related headaches and an extended top-end, AEA carries the natural and calm presentation of vintage ribbon microphones to the demands of a modern workflow. Both the N8 and KU5A are excellent ribbon microphones that share the same DNA and are designed for particular situations.
If you want to remove the "room" from your recordings, the KU5A will do just that. While the N8, or better yer a pair of N8s in Blumlein, will put the listener directly into the hall that the performance takes place. Either way, a gorgeous sounding recording is guaranteed.
Three M/S Setups for Classical Guitar
Capturing the natural room sound of the guitar.
The Mid/Side microphone technique has almost a century of history. Developed by Alan Blumlein in the early 1930s, it became popular in the broadcast studios because of its compatibility with mono. Even in the recording studio, it appears to have many advantages over the most commonly used stereo techniques.
With small instruments like the guitar, it is easy to capture a too wide of an image, resulting in an unrealistic and often a blurry reproduction, especially with ORTF and AB techniques.
Neumann TLM 193 & TLM 170 in M/S Stereo
The "Mid" microphone of M/S provides a solid capture of the instrument, while the "Side" microphone is responsible for picking up the ambience of the room. The right balance of the two microphones allows for a truthful image of the guitar realistically placed in the sound field.
The M/S technique gives you the most control over the stereo spread, but the best part is that you don't have to commit to any balance until the mixdown, as you can always change the balance long time after the recording is finished.
Things to consider
As the "Mid" microphone is responsible for capturing the actual sound of the guitar, it is essential to take the time and make sure that it's placement is optimal. Otherwise, there is not a lot you can do to fix it. Also, if the room ambience is not pleasant there is not a lot you could do to improve it, so you are better off with a close AB technique and using artificial reverb in your DAW during mixing.
Here is one of several M/S setups that I've tried this week. I placed the "Mid" microphone at a distance of 55cm from the top of the guitar, aiming at the midpoint from the bridge and hole. With the capsule being at 96cm high, slightly angled downwards, placing it on-axis with the angle the I hold my classical guitar.
The "Side" microphone with a Figure-8 pattern was simply placed on top of the other at 90 degrees, aligning the capsules as close together as possible, minimizing phase issues. The whole setup was angled slightly to the sidewalls of my room. The room is medium-sized, with a wooden floor, high ceiling and a few interesting angles on the wall, making it relatively live-sounding.
Austrian Audio OC818 M/S Pair
Austrian Audio OC818 in M/S Setup
In this first example, I used an Austrian Audio OC818 pair with the "Mid" microphone was set to cardioid. The response of the Austrian Audio microphones is fairly natural, especially at the low and mid registers. A slight boost is present at the higher frequencies, but it retains the very smooth character of the classic ceramic capsule, making the classical guitar recording to sound polished and vivacious, without any sign of harshness.
Gefell UMT70s M/S Pair
Gefell UMT70s in M/S Setup
The second example utilises a Gefell UMT70s pair, these mics have a unique appearance, an incredibly small grill and an unquestionably satisfying feeling to the touch, the craftsmanship is second to none. The UMT70s shows a distinct bright character with slightly recessed lows in its cardioid pattern. The Gefell microphones offer coloured pickup but maintain a smooth quality. In a way, this combination produces a somewhat more finished recording, with nostalgic charm, it reminded me of some Julian Bream albums. The result is pleasing but differs from the sound that I hear when I play my guitar, in my room.
Neumann TLM 193 and AEA N8 in M/S
Neumann TLM193 and AEA N8 in M/S Setup
An often overlooked aspect of the M/S microphone technique is that it doesn't require a matched pair of microphones. So for the last test, I decided to combine the Neumann TLM 193 with a ribbon microphone for "Side" duties, in this case, an AEA N8.
The TLM 193 has a natural pickup, with good low-end extension, flat mids and unhyped high-end. The most gratifying aspect of the Neumann is that it captures all the nuances of the classical guitar without emphasising any frequency. Additionally, it is dead silent which enhances dynamic playing styles as it allows the notes to fade to complete silence.
The AEA N8 offers an extended high-end in comparison to more traditional ribbons and a very juicy low end. This combination in an M/S setup produces a bigger soundstage and a sound that is reminiscing of the what I hear when I play.
Conclusions
All three setups can produce high-quality recordings, although the perspectives of their designs are different. I'm used to the Neumann sound, and I gravitate towards that, together with the N8 I think they produce the purest and calmest recording, but with the expense of some definition and the higher noise floor of the ribbon. The Austrian Audio microphones are the most versatile and they take EQ well. They are detailed, without sounding overly analytical, and offer an elegant and smooth sounding result. The Gefell combo sounds like an excellent record from perhaps a different era, but if you love that sound, it is impossible to get it with the other microphones.
Coda
The M/S Stereo technique has the potential to create outstanding recordings, captures a full-bodied and defined sound while eliminating phasing issues. Larger halls and resonant spaces are where it excels as it allows us to concentrate on the recording and fine-tune the balance of ambience and close sound during mixing.