SPL Crescendo duo Microphone Preamplifier Review
Gorgeously clean gain for your microphones
High-quality preamps that can capture all the nuances and subtleties of classical guitar are not as common as one might think, as most designs introduce too much noise and colour. When I came across the SPL Crescendo duo microphone preamp last year, I was intrigued by its specially designed 120-volt technology, which promises a particularly neutral, dynamic and low-distortion sound. I immediately contacted SPL and they sent me a demo unit to test.
Sound Performance Lab
SPL (Sound Performance Lab) is a German company that has been manufacturing professional audio equipment for about 40 years. SPL is known for its innovative designs and audio solutions of the highest quality. Their preamps, converters and headphone amplifiers are used in recording studios for music and film worldwide. Common features of all SPL products are the impressive build quality and enormous size.
SPL Crescendo duo Microphone Preamp
The Crescendo
The Crescendo 120-volt rail preamp design was introduced with the original 8-channel unit; the duo, as the name implies, is the stereo version, ideal for recording classical guitar in situations where good enough is not enough.
One of the ftings that sets the SPL Crescendo duo apart is its large knobs and tactile switches. Each channel provides from +18 dB to +70 dB of gain, which can be independently increased or decreased by 10 dB with a switchable output control. In this way, the rest of the chain can be supplied with an optimal level. The total output can reach up to 80 dB, which is more than sufficient for even the weakest ribbon microphones.
The physical VU meters for level adjustment leave a remarkable impression and can lower the displayed level by 10 dB if necessary. A high-pass filter of 6 dB per octave at 120 Hz is quite useful, although I would prefer it to be switchable for greater versatility. Nonetheless, every aspect of the Crescendo duo has been carefully thought out.
SPL Crescendo duo - tactile switches and VU meters
Four times more voltage
The 120 V technology operates at +/- 60 V. To handle such a high voltage, SPL has developed special proprietary operational amplifiers (SUPRA) that can operate at a such high voltages, as this would destroy conventional components and operational amplifiers.
How it sounds
After using the Crescendo duo in my recording setup for a couple of months, I am happy to report that it exceeded my expectations. The SPL has a very clean and transparent sound, which is essential when recording classical guitars. Many preamps introduce colouration and distortion that can detract from the subtleties and nuances of the recording. The result can sometimes be pleasant, but it strays far from the original sound and is usually not what we are looking for when trying to capture luthier-grade guitars and world-class guitarists. It's worth noting that unlike other clean preamps, the Crescendo is not a bit shrill, but has an overall smooth and warm sound.
A high-end setup & ‘The Music of the Impressionists’
I used the SPL Crescendo duo to record my latest album, The Music of the Impressionists, which contains a wealth of tonal colours, sustained tones, great dynamic differences, and silences. I used my beloved Essense guitar, handcrafted by Angela Waltner in Berlin, and in conjunction with a pair of Gefell M 950 microphones (review coming soon), another marvel of German engineering, and the RME ADI-2 Pro FS for the analogue-to-digital conversion, the Crescendo captured every detail brilliantly.
Listen to ‘The Music of the Impressionists’ on Spotify:
Comparisons
SPL Crescendo duo vs AEA TRP2
The Crescendo duo is similar in many ways to the AEA TRP2, another highly regarded preamp that I have used for several years. Both units are known for their clean and transparent sound, and both have low self-noise and high maximum gain. However, the Crescendo has a bit more refinement, smoothness and realism in its sound. The sonic benefits, additional features, and fantastic build quality of the preamp are worth the price difference. However, I will also keep the AEA TRP2 for some field recordings, as it is easier to transport.
Some thoughts on microphone preamps
Most audio interfaces have adequate preamps for most applications and users. So unless every other aspect of your recording chain is well thought out, searching for microphone preamps is a futile endeavour. The differences between clean mic preamps are only subtle but can become important when combined with other competent equipment and production skills. If you are confident in your setup and all you are missing is a good mic preamp, I'd suggest forgoing cheap deals and saving up until you can afford a high-end preamp like the Crescendo duo.
The Coda
The SPL Crescendo duo microphone preamp is one of the best options for recording classical guitar. It is a well-designed and sophisticated device that is capable of producing excellent recordings and is made to last a lifetime.
Stereo Microphone Techniques for the Classical Guitar
Stereo recording is the technique that involves two microphones that due to the captures the time differences of sound waves coming from a source, which gives depth and space to the recording. Similar to how our ears and brains record and process sound.
The Classical Guitar, albeit small, is an instrument with a complex sound and subtle peculiarities; and as such, it sounds better when is captured in stereo. Various stereo recording techniques have been developed since the early 1940s; each with distinct advantages and disadvantages.
If you ask, which is the best microphone technique for capturing the classical guitar in stereo, I'm afraid that the answer is not so simple. Room size, acoustics, the instrument, and the purpose of the recording, play a significant role; as well as our individual preferences.
In this article, I describe the most common stereo techniques from the point of you of a classical guitar recordist. I discuss their strengths and weaknesses, as well as prefered uses for each setup.
Note: This article is a work in progress; X/Y, M/S, and NOS setups will be added in the following weeks.
Spaced Pair Setups
AB Stereo
AB Stereo Array
The AB Stereo recording technique is based on a pair of spaced Directional or Omnidirectional microphones and provides in a pleasing and accurate capture with useful spatial information.
For home recordings, AB Stereo is one of the best options as it is easy to implement and get a consistent sound. A pair of Cardioids is usually preferred as they can successfully attenuate the room ambience.
Omnidirectional microphones capture the true low-end of the instrument though and have no proximity effect. You can position them closer to the source in a small room, or further away if the acoustics allow.
Application
Use a (minimum) distance of 20cm between the microphones for the most natural result. You can use a greater width, as the distance from the instrument increases, for a wider capture. I prefer a width between 30 and 40cm, for small/medium rooms, and up to 60cm for large halls.
If you position the AB Setup close to the guitar, you should avoid placing any microphone opposite to the soundhole, to prevent boominess. A microphone on each side of the soundhole will give the most balanced sound, off-axis towards the fretboard for more articulation or opposite of the bridge for a fuller sound.
The microphones are most commonly parallel to each other; but, since most microphones show a degree high-end directivity, we can fine-tune their response by angling them on the horizontal plane. If you aim them slightly outwards, you can attenuate some of the unpleasing mechanical noises of the guitar (fretting noises, squeaking, nails, etc.) You can also angle them slightly inwards to reject some of the room reflections.
The directional information as captured by an AB Stereo is not as accurate as of the coincident and near-coincident setups. This attribute can be an advantage if the performer moves a lot and assists in avoiding off-balanced results. I hardly ever pan the channels hard left and right, to preserve the integrity of the central image of the classical guitar.
The biggest drawback of the AB Stereo is its leaser compatibility with MONO playback (for example, a youtube video played on a smartphone); as a result, comb-filtering may be introduced.
Suitable Polar Patterns: Omni, Cardioid
Advantages
Easy implementation
Pleasing sound
Useful spatial information
Control of room ambience
Disadvantages
Playback in MONO may introduce comb filtering
Not the most accurate directional information
And here 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.
Near Coincident Setups
ORTF Stereo Technique
ORTF Stereo Array
Developed in the 1960s by the Office de Radiodiffusion Télévision Française, the ORTF is a stereo microphone configuration that with the use of two near coincident Cardioid microphones mimics the human ears.
The spacing of 17cm and 110° angle emulate respectively the distance between our ears and the shadow effect of the human head. The result is a realistic depiction of the sound field, both in directional and spatial areas, as well as a reasonable Mono compatibility.
Application
A pair of first-order Cardioid condensers is required for a proper ORTS, 17cm between the capsules and 110° angle. Other directional patterns can be used with respective changes in the width; for example, Schoeps suggests a distance of 21cm for the MK22 Open Cardioid capsules. You can also adjust slightly both the spacing and angle for the best sound.
The most critical aspect of ORTF is to balance the direct and diffuse sounds, as there is not much you can do in post-production afterwards. As always a minimum distance of 50cm is advised to avoid boominess, but I have had better results with a distance of 80cm to 110cm. At greater distances, a low-end boost might be required to compensate for the loss of low-end of directional microphones.
The ORTF main application is for large-scale sources, like orchestras and choirs. If positioned in a close distance, you might experience loss of focus with a perceived hole in the centre.
Consequently, depending on the room acoustics, the ORTF stereo array may be proved problematic in a home recording setting. As you might either have to place the microphones further away from the instrument, capturing the unattractive ambience of a small room, or suffer a smeary sound if you position the array closer.
Suitable Polar Patterns: Cardioid
Advantages
Realistic stereo field
Reasonable Mono compatibility
Disadvantages
Perceived Hole in the middle and loss of focus if positioned close to the source
Coda
Distance
The distance of the microphones to the source depends purely on the room size, the instrument, and the setup. As a rule of thumb, keep it smaller than that of the microphones to the front and side-walls. But never closer than 50cm.
Directional microphones have a sweet spot where the proximity effect eliminates, and the low-end frequency response becomes linear. If the microphones are not in the ideal position, you might need to apply a Low-Shelf EQ (boost or cut). Omnidirectional microphones have a better low-end response regardless of the distance but capture sound from all directions. So, be careful not to end up with an overly roomy recording.
Height
Most classical guitarists angle their guitars somewhat upwards to push the sound further back (and fill a concert hall). Correspondingly, the height of the microphones depends mainly on the distance to the guitar. The closer they are to the instrument the lower they need to be. If you place the microphones further away from the guitar, they need to be higher to retain definition and accuracy.
The sound travels as an impulse rather than a beam though, so there is some room for experimentation. If you prefer a fuller sound, you can position the microphones slightly lower. Contrarily, you can increase the clarity if you put the microphones higher. Use your ears and taste.
Vertical Angle
You can also exploit microphone angles in the vertical plane; you can increase clarity if they are on-axis with the top of the guitar, or aim them at a higher point to attenuate some of the high-end and undesired mechanical noises from the strings and nails.
About the Samples
Austrian Audio OC818 and OC18
I recorded all the examples with a pair of Austrian Audio OC818. I choose the OC818 for their clear sound, low self-noise, and multi-pattern options. The height of the microphones was 103cm (centre of the capsule), and the distance from the guitar was 90cm.
The signal chain was an AEA TRP2 Microphone Preamp into an RME ADI-2 Pro FS ADDA Converter.
I didn't provide samples in other distances as they would only give cues about my room and instrument, without adding value to you.
Closing thoughts
Recording the classical guitar is a meticulous exercise. Regardless, if you want to record your next album, a video for youtube, or your performances to share with your friends, it is an utterly satisfying process. It is also a reason to practice harder and become a better guitarist.
Before your press "rec" for the first take, allow some time to find the best position, height, and angle. It can be a matter of having an excellent recording or rendering the whole session useless. Small changes in this context may have dramatic results; they act as a physical equalizer.
There have been quite a few times that I had to re-record a performance because of a poor decision, or having to rely on heavy equalization to make it acceptable when it was (almost) impossible (or expensive) to record again at the same location.
I hope that this guide will be helpful in your recording adventures in the quest of capturing the best qualities of your instrument and room.
Austrian Audio OC18 Cardioid and OC818 Multipattern Condenser Microphones Review
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 new CKR12 ceramic capsule.
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?
OC818s in AB Stereo.
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 OC818.
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.
DPA 4011A vs Schoeps CMC6 MK22
Other than various Neumann microphones, the most used small-diaphragm condensers in classical concert halls and recordings are made by DPA and Schoeps. The philosophies behind their designs are quite distinctive, as are the usual descriptions of the family sound of each brand. Arguably though, they are more similar than different, as they both belong in the relatively uncoloured realm. But the big question remains; which microphone is better for recording the classical guitar.
To try and answer that question, for my needs and tastes, I had to get demo units of their cardioid microphones.
A Cardioid and an Open-Cardioid
The 4011A is a staple performer for many acoustic/classical instruments when a directional pick-up is required, Schoeps also offers a few different cardioid capsules with their Colette system suitable for a variety of uses. The MK22, which I chose for this shootout, is an open-cardioid. Schoeps describes its characteristics as a combination of the natural low-end of an Omni pattern with the benefit of cardioid directionality. In essence, it is a little wider than their standard cardioid capsule, MK4, and offers a marginally finer bass response.
Comparing the Polar Pattern plots of these microphones, I realised that the MK22 is closer to the characteristics of the 4011A than the MK4, making the decision easier, and this comparison quite logical.
DPA 4011A Frequency Response
DPA 4011A Polar Pattern
Schoeps CMC6 MK22 Frequency Response
Schoeps CMC6 MK22 Polar Pattern
It has nothing to do with sound
The DPA 3511A Stereo Kit
This might be a little unfair to Schoeps, but it's not my fault. DPA arranged for me to have for reviewing the 3511A Stereo Kit; a high-quality aluminium case which except for a matched pair of microphones, includes a lot of premium accessories, like their high-quality microphone mounting clips, shock mounts and a long stereo boom. All made with the highest standards and can be convenient in the field.
Schoeps CMC6 MK22 Set
From Schoeps, all I got was a pair of CMC6 bodies with the MK22 capsules. I know that ultimately the sound is what matters most, and I that can be evaluated without any extra accessories. But getting familiar with the DPA system, elevated my experience.
Another observation that doesn’t have to do with sound is that the NEXTEL finish of the CMC6 preamps and capsules is quite fragile, I thought I could scratch them, just by looking at them. In comparison, the 4011A have a more solid feel and seem more durable.
Setting up
As per my usual recording techniques for the microphone duels, I placed each pair at an AB configuration, with 36cm distance between them, 96cm from the ground and around 70cm from the top of my spruce guitar.
By listening to the samples, it is evident that both microphone pairs provide a solid performance. I would be totally satisfied with either, but there are some differences.
Unambiguous precision
The 4011As have a unique way to draw an utterly accurate and almost holographic image of the classical guitar, without any sign of harshness or hardness that is not a product of the performance. The sustaining notes, ring longer and the complex harmonies are captured clearer, like if they are taken apart.
Without sacrificing detail, the MK22 capsules portray an euphonic result. They are fast and analytic, but yet with a smooth and musical character; as if the performance is treated with a touch of kindness.
Au contraire, the DPA microphones will represent with unambiguous precision all the nuances and subtleties of a world-class instrumentalist and a high-grade luthier guitar; exposing likewise any flaws on a player's technique or the instrument. Their honesty can be brutal and overwhelming in some cases. If the source is good, they are going to reveal it; if not, forget about using them.
The Schoeps's offer a gentle depiction of the performance by applying a veil of wizardry and charming sweetness. However with the DPAs, it is like looking at the recording through a magnifying glass.
Noise concerns
My only gripe with the 4011A is the high self-noise. At 18dB-A the noise is not excessive and in most cases not even noticeable, but it can be bothersome for distant miking with softer instruments, or very dynamic musical styles.
The MK22 with 13dB-A of self-noise is almost as silent as my Neumann TLM 193 which have a remarkable 10dB-A of self-noise performance. In reality, most rooms are noisier than any of these mics.
Back to the original question
Honestly, I cannot say which microphone is better; probably neither is. The Schoeps have a sound, as the DPAs and ideally, I would love to own sets of both. In isolation, both pairs should sound stunning, if not, the problem is certainly not on the chosen pair of microphones.
When I'm not directly comparing and analysing them so closely, I believe that their differences are not as pronounced. Saying that, after hearing to my playing and guitar(s) with the 4011As (and 4006As which DPA also sent me), it is difficult to accept anything less realistic.
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.