Best Type of Microphone for Recording the Classical Guitar
One of the most usual questions I get asked is which microphone is the best for capturing the classical guitar, but as with all deep questions in life, I'm afraid there is no simple answer. Our guitars, nails as well as playing techniques differ vastly. Besides, our rooms have unique properties, and of course, our tastes vary. Another decisive factor is our listening environments, but that's a subject for another day.
I've written on Classical Guitar Tones extensively about the different microphones, brands and models. If you have been here for a while, you've seen me test all sorts of microphones, entry-level to high-end. In this article, I take a step back and present my thoughts on the different types of microphones, their strengths and weaknesses. Plus some words on the different polar patterns.
On being passive
Ribbon microphones have a relatively simple design with no active circuitry and use a thin metal ribbon suspended in a magnetic field. Most ribbon designs hear sound bi-directionally and produce natural and complex recordings. They have the reputation of being fragile and need careful handling and storage.
Dynamic microphones are similar to ribbons as both capture sound by magnetic induction. In contrast, they are very robust, resistant to moisture, and have low sensitivity. In practice, they offer no real asset in classical guitar recordings as their advantages benefit mainly on-stage use and capturing of loud sources.
For the most part, I don't get along well with ribbon or dynamic microphones, mainly because of their sensitivity or lack of. I often play soft passages or employ silence in my music, and with passive microphones, one has to crank the gain on the preamps to get sufficient levels, resulting in unwanted noise. After all, the classical guitar is a soft and delicate instrument, and no matter which preamps you use, it is impossible to get noiseless classical guitar recordings with passive microphones.
Ribbon microphones are also quite forgiving to the various mechanical "non-musical" noises, such as nail and fretting sounds. And this is why some people love them, especially on harsher and louder instruments and a less subtle repertoire. But, I find the response of most but the finest ribbon microphones, principally with the thinnest ribbons (some Royer, AEA, and Samar makes come to mind), quite sluggish.
Phantom power required
Nowadays, there are a plethora of active ribbon microphones, purposed for capturing softer sources and being less dependent on the preamp choice. These tend to work better with classical guitar. Yet, even high-end active ribbon microphones are far from being noiseless. I understand that for some people noise is a nonissue, but for me, it is a distracting element. I like deep blacks and hate when the softer parts or rests are being washed away by preamp hiss.
Also, the figure-eight polar pattern found in most ribbons makes them less than ideal for many recording situations. They do work nicely as a side microphone in an M/S stereo array.
Capacitors move the (recording) world
Condenser microphones require a power source to function and generally produce a high-quality audio signal mainly due to the small mass of the capsule. They can capture on tape utmost detail, sometimes even too much of it, and are the most used transducers in recording sessions and concert halls.
Most of the classic designs have been either tube or transformer equipped condensers, but with the dominance of digital recording, transformerless solid-state condensers have increasingly gained popularity in classical recordings for their additional clarity and lower self-noise.
Size matters
Condenser microphones are categorized by the size of their diaphragm and come in two main types: small-diaphragm, like most Schoeps' and the Neumann KM184, and large-diaphragm, like the Neumann U87 and AKG C414.
So, which one is better for the classical guitar, you may ask? Not so fast. Again, the answer is not straightforward.
Let's talk first about their differences.
Small diaphragm condensers are usually more accurate, with a faster transient response and superior off-axis response. They are also smaller and lighter, so they are easier to carry, besides being visually unobtrusive. The latter is a decisive factor in why SDCs dominate the concert world.
Paying audiences generally don't enjoy seeing a stage the musicians surrounded by several dozens of microphones and bulky heavy-duty stands to support them. Neumann, Schoeps and DPA provide small-diaphragm condenser systems with every possible polar response and mounting option a classical sound engineer might on location.
Polar patterns say more than you think
The downsides of using SDC's on a classical guitar, especially at home, are only a few but nontrivial. Small-diaphragm condensers are tuned for specific roles. Directional microphones are either purposed for close spots on soloists, used in combination with a stereo array at some distance, or for the main pickup and thus are tuned to compensate for the high-end frequency loss that occurs. The result, when used inappropriately, is either a poor low-end response or hyperrealistic recordings with exaggerated high-end. In other words, they can easily sound thin and harsh.
On the other hand, SDCs with an omnidirectional response (the real microphones), especially those that have been tuned for the free field, offer an optimal response at both ends of the spectrum. Additionally, they provide greater flexibility in positioning owing to the absence of proximity side-effects but become a challenge to use in non-treated rooms that universally suffer from early reflections and standing waves.
Microphones with wide- or sub-cardioid polar characteristics come to close the gap, with a better low-end response than their cardioid cousins, some room rejection, and sometimes less pronounced high-end. Unfortunately, small-diaphragm cardioids with such polar patterns are rare, and except for the bargain Line Audio CM3 / CM4, they are always on the expensive side.
So, where does the good old large-diaphragm condenser fit?
Generally speaking, LDC's suffer from a pronounced proximity effect, transient smoothing and suboptimal off-axis colouration. In addition, they require sturdier stands, are more difficult to position due to their size and weight, and can be quite visually intrusive in videos.
All these intricacies cannot be good, right? Moreover, excellent sounding large-diaphragm condensers suitable for the classical guitar are quite rare and expensive, as most LDC's are targeted for vocal pickup.
Any advantages?
As I wrote above, noise on a recording can be distracting. The smaller the size of the capsule, the greater the self-noise of condensers. Tube and transformer-based microphones are also subject to higher noise levels. Therefore, transformerless large-diaphragm condensers have lower noise to signal ratios, with several Gefell, Austrian Audio, and Neumann models reaching nonexistent self-noise figures.
Likewise, many universal studio LDC's grant additional flexibility, as they bring multiple polar patterns, removing the need to own or carry multiple microphones or capsules on a session. With a modern microphone, like the excellent and most versatile Austrian Audio OC818, you can not only choose on the fly between any possible polar pattern, but you can also do it long after the recording has been completed.
Here is my recording of Debussy’s Prelude VIII. Recorded on location with a pair of Austrian Audio OC818s.
Let's proceed to checkout.
One can make a good recording with any decent microphone, some experimentation and post-production skills to boot. There are no excuses for bad recordings in 2022.
On a budget, neither ribbon nor large-diaphragm condenser microphones of decent quality can be found as cheaper offerings are made either for a vintage vibe or vocalists in mind. Line Audio's small-diaphragm condensers are the undenied kings of the entry-level recording setup.
When searching for a high-end classical guitar recording setup to capture a world-class guitarist with a magnificent guitar in an excellent sounding room, a pair of exceptional and well-positioned omnidirectional or somewhat directional condenser microphones is hard to beat. DPA, Gefell, Austrian Audio and several high-end Neumann condensers come to mind. In such a scenario, the size of the diaphragm is incidental. With less ideal conditions, even high-end SDC's on a solo classical guitar, be it directional or not, can expose flaws and produce unattractive recordings.
To conclude, in most situations I favour large-diaphragm condenser microphones for their inherent sound qualities and noiseless behaviour. First-class LDCs can produce a luxurious recording and provide a pleasant listening experience. I also like how they look on videos; unapologetic, proud and predominant, almost commanding. With that said, the realism that some of the best SDCs treat the listener when every element is exemplary can be breathtaking.
Perhaps it is more advantageous to bring together small- and large-diaphragm condensers in an elaborate three- or four-microphone array.
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.