Immersive Microphone Technique Shootout

Immersive Mic Array and Blackmagic Ursa Cine Immersive Camera

GOAL

To compare various multi-channel microphone techniques including immersive spaced array (PCMA-3D), Ambisonics, Decca Tree, and AB Stereo Pair in a controlled setting.   With particular focus on the immersive performance of the PCMA-3D Array vs 1st Order Ambisonics.  Key questions – how large is the gap between a $22,000 microphone array and a $1,600 Ambisonics mic?  Is the gap large enough to justify purchasing the more expensive solution?  Is that gap purely aesthetic?  Is there a gap at all?

Another core goal of this project was to create an immersive experience for the Apple Vision Pro including both immersive audio and video.  So, in addition to the scientific comparison, there is also an important deliverable component to this project.  Thoughts on that process can be found in a future post (link to follow soon).

PROJECT DETAILS

A live performance of Mozart’s Piano Quartet in Eb Major.  Instrumentation:  piano, violin, viola, and cello.  Recorded in the Audio Temple at Full Sail University in Orlando, FL in October 2025.  Darren Schneider was the supervising engineer with Meredith Douglas assisting.  Blackguard Sound oversaw the immersive component, capturing both immersive audio and video using the Blackmagic Cine Immersive camera. Special thanks to Eric Jacobsen and the rest of the ensemble for allowing us to record their wonderful performance. 

TL: DR COMPARISON TABLE & TAKEAWAYS

This post is admittedly quite long.  Here’s a quick comparison and our key takeaways.  We’re spoiling a bit right at the beginning, but please read on after the TL: DR section if you want all the specifics.

Comparing the Schoeps PCMA-3D V1 array with the Sennheiser AMBEO

The Schoeps PCMA-3D array is the gold standard when sound quality is all that matters.  The added expense and more complex setup are justified for ultra-discerning clients with a suitable budget in controlled environments.  The AMBEO (or a similar fully coincident, Ambisonics array) is a perfectly suitable option when there are other considerations at play, like when a smaller physical footprint is required, when setup time is a concern, or when budgetary constraints don't permit the PCMA-3D.

The tonal differences between the two options come down to a matter of taste - we felt the AMBEO was better suited to a production that included video as it more realistically captured the performance but that the PCMA-3D array (with it’s flattering portrayal of the instruments) lent itself better to a purely auditory immersive experience.  The differences in immersive quality are minor, and smaller than we expected.  We felt the AMBEO actually outperformed the PCMA-3D on one of the three spatial axes.  The common wisdom of Ambisonics mics having a smaller sweet spot may be overstated.  We didn’t perceive a notable reduction of the sweet spot, but this was only achievable through careful mastering using state-of-the-art tools.  (See the section below: ‘A Note on Processing Ambisonics Recordings’)

In our opinion, the PCMA-3D array is superior, but we don’t think it’s a 10x improvement, or even a 2x improvement.   More like a 1.2 – 1.5X improvement.  Of course, all of this is highly subjective which is why we’ve included files to perform your own analysis.   All things considered, the AMBEO performed very well, but with the caveat that it took a lot of work and a suite of Audio Brewers (and other) plugins to get there. In our estimation, the post-processing performed on ambisonics recordings is as important as the mic itself. An ambisonics mic alone is practically useless. It’s impossible to overstate the importance of a proper plugin suite and careful mastering process!

OK, now to the details…

Another angle on the setup.

BACKGROUND

We’ve been immensely curious about the PCMA-3D microphone array (v1), which was developed by Dr. Hyunkook Lee of the Applied Psychoacoustics Lab (APL) at the University of Huddersfield.  The array consists of 11 microphones arranged in two height layers that are horizontally spaced but vertically coincident.  A special area of interest for us is how this immersive recording method compares to fully coincident techniques (Ambisonics), which we are familiar with from our field recording work.  Of course, we’ve read about the differences between spaced and coincident microphone arrays but there is no substitute for first-hand experience and a trained set of human ears. 

Vertically coincident pair

Immersive microphone arrays are expensive!  When this opportunity came up, we elected to rent a set of Schoeps mics for the PCMA-3D Array from SoundMirror in Boston.  SoundMIrror is our go-to source for high-end or obscure microphones, and we highly recommend them for your rental needs.  An aside on Schoeps mics – these are just about the only mics you ever see in these types of arrays.  There are other options on the market (see our previous blog post comparing some of the options), but we went with Schoeps for two reasons: 1. Before experimenting with other models of mics, we wanted to somewhat control the experiment by using the established industry standard.  2. Schoeps won our mic shootout (even if the outcome was closer than we initially expected). 

The Decca Tree and AB Pair were primarily for reference, as those are well-established mic techniques for classical music.   Comparing the immersive arrays with stereo techniques will give us an even more complete picture.  Ultimately, we elected to use the Decca Tree in the final mix, so it was worth it!

EQUIPMENT LIST

PCMA-3D Array (v1)

5x Schoeps MK-4 Cardioid

6x Schoeps MK-41 Super Cardioid

RME 12Mic Dante Preamps

Triad-Orbit modified Decca Tree stand

Ambisonics

Sennheiser AMBEO 1st Order Ambisonics Mic

Sound Devices MixPre 6 Field Recorder

Decca Tree

3x Austrian Audio OC818

SSL Duality into Pro Tools

AB Stereo

2x Schoeps MK-21 Wide Cardioid

SSL Duality into Pro Tools

CAPTURE METHODOLOGY

The instruments were arranged in the typical piano quartet fashion.  Piano in the back with strings in the foreground.  Arranged left to right:  violin, viola, and cello.  The reference location for our immersive test was twelve feet in front of the strings (eighteen feet from the piano) centered on the viola, which represented the center line of the ensemble.  At this location, we aligned the center channel microphones of the PCMA-3D array and the Decca Tree.  The Decca Tree was placed at approximately eight feet in height, with the PCMA-3D array at about seven feet.  Under the center channel mics, we placed the AMBEO at about six feet.  Finally, the AB stereo pair was centered on this point at about six feet high.

Immersive Mic and Camera Placement Detail

The immersive camera was placed between the microphone arrays and performers, about eight feet from the strings, centered on the viola.  The tripod was set so that the camera was about five and half feet high (rough approximation of average human height).

To ensure matched gain, the PCMA-3D Array was amplified with the RME 12Mic Dante, a 12-channel preamp with linkable, digitally controlled gain.  From there, 11 channels were recorded into Pro Tools. 

The AMBEO was amplified by a Sound Devices MixPre6 running the Ambisonics plugin.  The raw A-format was transcoded live in the MixPre6 and recorded in AmbiX format.  Once again, all four gains were linked and digitally controlled.

Immersive Recording with RME 12 Mic Dante and Sound Devices MixPre 6

The Decca Tree and A/B Stereo Pair were amplified by the Audio Temple’s SSL Duality console (with no ability to match gains, other than by ear) and recorded into Pro Tools along with the close mics for each instrument (a stereo pair of Neumanns on the piano, DPA pencil mics on the strings).  The close mics were for mixing but aren’t relevant to this comparison.

All channels were recorded at 48K / 24-bit.

PRO TOOLS SESSION SETUP

All 25 microphones were imported into a unified Pro Tools session for mixing and comparison.  The respective arrays and pairs were panned, grouped, and subbed together.   Every element was bussed into a 9.0.6 Object Bed and sent to the Dolby Atmos Renderer.  The output of the Dolby Renderer was monitored in 7.1.4 at Blackguard Sound. 

Screenshot of mix session in Pro Tools (PCMA-3D in blue / AMBEO in orange / Decca Tree in green / Stereo A/B in yellow / Close mics in purple)

Each microphone array / pair was time-aligned to the camera perspective.  The center channels of the PCMA-3D and Decca Tree arrays were used for reference, with the time of arrival differences between each mic in the array preserved. 

The AMBEO was upscaled and decoded using Audio Brewers plugins.  First, the 1OA recording from the MixPre6 was upscaled to 7OA using ab HOA Imager and Upscaler (yes, the Advanced Upscaler does this internally, but in cases like this I prefer to have the full spatial control that the Imager provides).  Then it was decoded to 9.0.6 using ab Decoder HOA and fed into the Object Bed with the other mics.

Audio Brewers Imager and Decoder processing the AMBEO

Each microphone array / pair was clip gained to -20LKFS (using meters in the Dolby Renderer as my guide) to ensure a fair comparison.  We’re all familiar with the effect of ‘louder is often perceived as better’ so care was taken to ensure an honest comparison.

PROCESSING

Each microphone array / pair was equalized using FabFilter ProQ4 across their respective sub auxes (this could be stereo, LCR, 7.0.4, or 9.0.6 depending on the mics in question).  The first EQ pass was done to taste with no attempt to EQ match between the groups.   The EQ was strictly subtractive – mostly clearing up excessive low-mid room resonances in the piano and taming some of the shriller high-mid resonances in the strings.  Spectral and Dynamic EQ settings were employed to remove the offending frequencies as surgically and transparently as possible. 

The PCMA-3D array needed the most help with the piano buildup.  We chalk this up to having 11 mics and thus 11 times the buildup.  To accomplish this, we created a sidechain bus consisting of the close piano mics.  This sidechain bus controlled the behavior of the spectral EQ on the array, serving to reduce some of the loudest frequencies of the piano specifically, while leaving the low end of the cello alone for the most part. 

A NOTE ON PROCESSING AMBISONICS RECORDINGS

As always, utmost care should be taken when working with Ambisonics recordings.  I typically EQ my Ambisonics recordings before upscaling.  To preserve the best possible spatial imaging, plugins should be in linear phase mode and any processing applied needs to be identical on each channel.  This means the plugin must be in multichannel mode (as opposed to multi-mono).   

As many of us working with Ambisonics know, FabFIlter does not support Ambisonics channel widths in multichannel mode.  For basic EQ, this is not a problem.  The same processing will be applied to every channel.  However, when using dynamic EQ (or any dynamics processing for that matter) this raises serious issues.  In multi-mono mode, each channel will be processed independently based on their individual amplitudes, and the gain reduction will be dramatically different between one channel and the next.  One way to observe this in ProQ 4 is to open the ‘instance list’ view where you can see the mono processing on each channel.  Make an EQ band dynamic, turn on the gain reduction, and observe as each channel does its own thing.  Not good. 

Dynamic EQ Misbehaving in Multi-Mono Mode

However, there is a work-around that makes this workflow possible. Sidechaining is the key... (See what I did there?)   My method is to duplicate the 1OA track and route it to a dummy output.  Then I create a mono bus called ‘ambisonics key’.  Put that bus on a send of the dummy Ambisonics track and set the send level to unity.  Next, go to the ProQ 4 instance inserted on the non-dummy Ambisonics track.  Set the sidechain input to the bus you made (this is in the plugin header, top left).  Then, go to the band that you want to use dynamically.  Open the disclosure triangle and click the icon to enable sidechain input.  Set the threshold and gain reduction controls to taste.  Finally, open the ‘instance list’ view and observe how all the channels of the multi-mono plugin are now reacting in tandem!

Relevant FabFilter Pro Q4 controls

ProQ 4 in Sidechained Multi-Mono Working in Tandem

That was a bit of a detour, but crucial to understanding how to make a fair comparison by not destroying the spatial image in the Ambisonics recording.  The AMBEO needed its typical cleanup in the 400-500 Hz range.  I consistently scoop out 3dB fairly broadly in this area.  This is simply parametric EQ (no dynamic or spectral processing) and I have to do it on every recording I make with the AMBEO.  If the mic has one sonic flaw, it’s this.  But once you know about the issue, it’s easy to address.  Then I applied more advanced EQ techniques to suppress resonances - similar to the processing on all the other mics.

MATCHING THE IMMERSIVE RIGS

The most important aspect of this exercise was to formulate a comparison between the two immersive techniques.  This meant matching them as closely as possible in both the frequency and spatial domains.  I decided to use the PCMA-3D array as the control since, in my estimation, the AMBEO would need to punch up to get to the same level.  With repeated A/B comparison, I tweaked the EQ of the AMBEO to be in the ballpark of the PCMA-3D.  Then, I focused on the spatial aspects.  I manipulated the width, depth, and omni controls in ab Imager to approximate what I was hearing on the PCMA-3D.  I feel I was able to get them close enough to formulate an opinion.

EXAMPLE AUDIO

Here is a Dolby Atmos ADM containing a few example clips comparing the two immersive microphones.  Note that this is not representative of the final mix for consumption in the Vision Pro - this is presented more ‘straight up’ for comparison. Each snippet is played twice.  The first play-through is the Schoeps PCMA-3D array and the second is the Sennheiser AMBEO.

And here is a binaural re-render for those who don’t have a way to play back the ADM.

The provided audio files are for demonstration purposes only and are the intellectual property of Blackguard Sound, Eric Jacobsen, and Full Sail University. No unauthorized use is permitted.

CONCLUSION

Our big takeaways:

The PCMA-3D array is amazing, but also expensive and cumbersome.  If quality is the chief concern, this is the way to go.

The Sennheiser AMBEO, when compared to the PCMA-3D array, performed surprisingly well given its cost-effectiveness and ease of setup.  But the tradeoff is a slightly more complex mix and a slightly less convincing immersive recording.

Both solutions were capable of producing a viable product.

Recording with some traditional mono and stereo techniques can augment spatial recordings and are still not only useful, but mandatory.

Microphone Shootout - Immersive Spaced Array

The setup - three ORTF stereo pairs.

Intent

We’re working on expanding our immersive audio recording capabilities, particularly in the realm of immersive music.  One of the ways we’re looking to expand is into spaced microphone arrays.  Everything Blackguard Sound has commercially released up to this point has been recorded with coincident arrays (1st or 2nd Order Ambisonics).  There are many benefits to Ambisonics, but there are some tradeoffs, too.  We’re primarily concerned with the size of the sweet spot, which can be quite small.  Outside of that sweet spot phasing becomes apparent and it can feel a little dizzying.  We’re working on postproduction methods to decrease this effect, and the results are encouraging.  But one of the benefits of spaced arrays is a more stable, enlarged sweet spot.  That said, we will most likely continue to use Ambisonics mics for field recordings due to the obvious logistical challenges of bringing spaced arrays into the field.

We’ve experimented in the past with quad spaced omni (with meh results) and a proprietary technique devised in conjunction with Darren Schneider at Full Sail University.  This novel technique places the performer(s) in the center of 11 microphones at the Dolby recommended Atmos speaker placements, pointed inwards.  Then in post, each mic is converted into a Dolby Atmos object and panned to its placement in the room.  The results of this experiment were more encouraging.  The immersive image is very high fidelity and interesting, but perhaps hyper-real.  It almost places the listener inside the instrument or inside the performer’s perspective.  We thought it was pretty cool, but the feedback from classical music aficionados was almost exclusively ‘I am not used to that perspective, and I don’t think I can get used to it’.  So, our research into spaced arrays continues. 

The Full Sail immersive mic technique in action

One spaced array in particular has sparked our curiosity.  The PCMA-3D (Perspective Control Mic Array) by Dr. Hyunkook Lee.  It’s influenced by existing classical music recording techniques but enhanced to be compatible with immersive audio.  This technique requires eleven mics (a mix of cardioids and super cardioids) arranged in a one-meter square with seven mics on the horizontal plane and four aimed upwards (coincident with the four corners of the square).  Phase one of our spaced array journey will be testing.  Phase two will be purchase and adoption.  Buying eleven high-end microphones is a substantial investment, so we will be renting mics for our initial experiments.  But even renting is an expensive proposition. - it will cost about $1,700 to rent eleven high quality mics for a week!  So, with that in mind we devised this microphone shootout between the three front-runners in the hopes of narrowing down our options.

The Three Options

Schoeps MK 4 / MK 41

These are the mics to beat.  We have a stereo pair of MK 41s, and they are our favorite mics for sound effects recording.  They have an uncanny ability to capture the space of a room.  On headphones, it’s a borderline immersive experience.  I have been genuinely startled while editing under headphones when an off-axis sound seemed to come from behind me.  Since the goal here is maximum immersion, it’s going to be tough to beat this mic.  There are two downsides to these mics, however.  The first is expense.  These retail for $2,000 each.  Multiply that by eleven and we’re looking at the cost of a reasonable new car.  The second is their susceptibility to humidity.   As much as we love these mics, it’s just not possible to use them outdoors here in Florida (or any other sub-tropical or tropical climate).  As stated above, we’ll probably continue using Ambisonics mics in the field, but if we’re going to spend a crazy amount of money on mics, we’d prefer to have the option of using them outside.  We used the MK 41 (super cardioid pattern) for this test.

Sennheiser MKH 8040 / MKH 8050

We have tons of experience with Sennheiser mics.  The AMBEO is our go-to mic in the field, and we’ve used MKH 50s and MKH 60s recording dialog on countless film sets.  The 8040 and 8050 are updated versions of that older generation.  The 80 series is meant to be interchangeable with the older mics, but we’ve heard anecdotally that this isn’t entirely the case.  However, for the purposes of this test we’re using the older MKH 50 since that’s what we have access to.  This approach may prove the be flawed, but I suspect these mics are close enough to help with our decision.  The upside of the Sennheisers is that they are slightly more affordable at $1,500 each.  Also, they are RF condensers, so their high humidity performance is immaculate.  Even if we aren’t utilizing the full array, we can use these mics in the field for a variety of other applications.  We used the MKH 50 (super cardioid) for this test.

Neumann KM 184 / KM 185

These are the wild cards.  The KM 184 is well known in the music industry but not widely used in sound effects.  I have used the Neuman KMR-8 shotgun mic for dialog.  Like the Schoeps, it does not deal well with humidity.  One time on a short film set, there was a company move from inside to outside.  I think the KMR-8 lasted about 20 seconds before it started sputtering from humidity!  But the Neumanns are well regarded for studio work, and their price point makes them much more attractive.  At $850 each, it’s a much more reasonable proposition to get eleven of these.  My main concern for studio work is a presence boost around 4K, where the other mics are reasonably flat.  There’s only one way to find out if that boost is going to be an issue!  We used the KM 184 (cardioid) for this test.   Yes, the other two mics in the test are super cardioid, but we live in an imperfect world.

That’s a bunch of German mics.

Methodology

Placement

I decided to use ORTF placement for the three stereo pairs.  This is my personal favorite stereo technique.  My experience with the MK 41s is exclusively using them in ORTF configuration and this is how I’ve achieved borderline spooky imaging with them.  ORTF requires the mic capsules to be 17cm apart and at a 110-degree angle.  I tried to get them as close together as the mounting hardware would permit.  I was able to place the three ORTF pairs in a vertical stack approximately two inches apart.  I hope that’s close enough to not introduce any major variables.  The timing discrepancy between the earliest pair and the latest pair was less than 1ms, so they were very close.  To my mind, the more important variable was being able to record the exact same material on each pair simultaneously for the cleanest possible comparison.

Detail of the setup

Amplification

This is the variable I was most concerned with.  For this test to work, the gain has to be identical for all six mics.  Ideally, the preamps would be digitally controlled.  My RME UFX+ only has four digitally controlled mic pres.  Our Sound Devices MixPre10 has 8 linkable preamps, but I didn’t want to have to dump files afterward or set it up to work as an interface.  My remaining option was to use a Sonosax SX-ES64, which is a high-end production mixer.  It has a unique 3-way gain selector (instead of a mic/line switch).  I set the switch to the mid setting and kept the gain knobs all the way down.  From there, I took six pre-fader outs and plugged them into a Ferrofish A/D converter.  It’s possible to link the gains on the Ferrofish, so I was able to ensure that all six mics got the exact same amount of gain.

Sonosax Production Mixer

Linked gains on A/D Converter

Test Material

I decided to use four very different sound sources to get the widest possible variety of volumes and timbres.  The four sound sources were: Alto Saxophone, Classical Guitar, Voice, and Percussion.  I then recorded each instrument at two different perspectives that I’m calling ‘near’ and ‘mid’.  Near was about five feet from the mic array and mid was about 15 feet away.  Blackguard’s studio space is not really intended for tracking acoustic instruments.  But it’s a treated room, and it’s relatively quiet so it’s not the worst.  While I wouldn’t want to use these recordings on an album, I think they’re perfectly fine for the sake of comparison.

Sound sources

Analysis

I recorded both performances of each instrument into Pro Tools.  Once I was done recording, I decided to measure the performance in two different ways.  The first way is objective analysis, measuring levels (pseudo) scientifically.  The second is subjective analysis using my ears to pick a favorite.

Pro Tools timeline

Objective Measurement

I measured each recording using iZotope Insight 2.  I was looking at three things: Integrated LUFS, True Peak, and Noise Floor.  The integrated LUFS gives me an idea of the mic’s output.  The True Peak (when compared to the integrated LUFS) gives me a rough sense of dynamic range.  Those two measurements are straightforward.  The noise floor measurement is probably flawed, but it is an ‘apples to apples’ real-world comparison.  In each recording, I made sure to remain perfectly quiet for about five seconds.  I then separated this ‘silence’ into a new clip and measured the LUFS again.  However, the LUFS meter doesn’t do great with very quiet recordings, so I raised the clip gain of these ‘silent’ clips by 12dB to get a reliable measurement.  The studio isn’t exactly an anechoic chamber but given the same source material and same gain the only variable SHOULD be the mic’s inherent self-noise. 

Insight 2 measurement

Detail of noise floor measurement

Objective Results

I bet a real acoustician would eviscerate this analysis, but for my needs I feel I got some good information.  For example, the MKH 50 was WAY hotter than the other two.  The MK 41 consistently had the lowest output.  The KM 184 had the lowest noise floor and the most dynamic range.  These things were true across nearly all instruments and perspectives.   Surely, there’s value in this intel.

Some objective measurements

Subjective Measurement

I decided to evaluate each mic pair on two subjective aspects: tone and space.  Tone being the frequency response of the mic and the resulting attractiveness on each source instrument.  Space being how convinced I was by the spatial imaging.  This was the biggest benefit of recording in our studio.  I know the space well and it was very easy to hear the difference in each pair’s spatial performance.  I assigned a rating to each mic for every instrument and perspective:  one for my favorite, three for my least favorite.  The mic with the lowest score wins the subjective analysis.

Subjective grading

Subjective Results

The MKH 50 was the easy winner in the tone category.  The highs are clear and articulated without being harsh.  As an added bonus, the MKH50 (and the 8050) extend well into ultrasonic frequencies – not relevant to this test but as a sound designer I’m a fan.  The MKH 50 also had the best low-end response of any of the mics.  This was especially apparent on the percussion recording and I feel the other two mics really lost something in this regard.  The MK 41 and the KM 184 were much closer to each other, tonally.  I preferred the MK 41, but only slightly (there was only a two-point difference between them). Given the price difference between these two mics, I was pleasantly surprised by this.

The MK 41 was the clear winner in the space category.  It has a nearly magical way of making the space feel authentic.  I suspected the MK 41 was special in this regard and the results of this test confirmed my suspicion.  The KM 184 was the next best, but I still preferred the MK 41 by a nearly 2:1 margin. The MKH 50 lagged far behind the other two.  When compared directly to the Schoeps mics, the Sennheisers practically collapsed to a phantom center that feels like a single point as opposed to really feeling the width and depth of the room.

So, there’s a bit of a problem here.  The MKH 50 was my favorite from a tone perspective, but my least favorite from a space perspective!  What were the final combined scores?  Maybe that will help…The KM 184 finished last with 35 points.  The MKH 50 finished second with 32 points.  The MK 41 finished first with 27 points.  OK – so we have a winner but it’s not a blowout.

Final results - overall, tone, and space - low score wins

Synthesis and Key Takeaways

The MKH 50 was the outlier – it consistently felt like a totally different beast on every source.  If this decision was based purely on tonal quality the MKH 50 would have run away with the victory.  However, the whole point of this exercise is to evaluate these mics for use in an immersive array and the MKH 50 lagged far behind the others in this regard.  Despite all the other things the Sennheiser mics have going for them, I think they need to be excluded from consideration. Perhaps this is unfair, and we need to acquire a pair of the newer 8050s for truly fair testing…

The Schoeps MK 41 and the Neumann KM 184 felt much closer to each other.  The KM 184 was just a little harsher (that presence boost rearing its head) and a little narrower.  But I need to stress ‘a little’.  I had to really dig in and A/B a lot to come to this conclusion.  For me, this was a surprise for a couple of reasons.  First, the difference in polar patterns.  I was concerned about using the cardioid KM 184 for this experiment since the other two mics are super cardioid.  But it turned out to be less of a factor than I anticipated.  I’d really like to get ahold of a pair of Neumann KM 185s, which is the super cardioid version, and compare it against the MK 41.  I wonder if that mic would close the gap in the space category…

The technical specs were consistently quite good for the KM 184.  Lowest noise floor. Highest dynamic range.  Middle of the road output.  Least expensive by a lot.  Truly impressive.

This leaves us with a tough decision.  The MK 41 is my clear favorite.  But is it $1,100 better on a per-microphone basis?  Definitely not.  Let’s do some quick math.  A $1,100 price difference per microphone times eleven total microphones in the array comes to a $12,000 difference!  That’s going to be hard to stomach.  There’s an argument to be made that quality and results are all that matter.   I tend to agree with this sentiment, and I’ve never been one to shy away from spending up for professional tools.  However, the difference between these two mics is not that wide.  In the short term, I think we need to rent a pair of the Neuman KM 185s and do another shootout 1v1 with the MK 41s.  If the gap is closed even further this decision will get a lot easier.  For now, my intuition says the KM 184/ KM 185 combo is the right choice but stay tuned to see what we ultimately decide.

Immersive Field Recording with the Sennheiser AMBEO

Blackguard Sound specializes in immersive field recording. We’ve tried several techniques including Double Mid Side, 1st Order Ambisonics, and 2nd Order Ambisonics. We’ve even experimented with recording a solo cello with 17 mics configured for immersive playback (but that’s a separate post)! Our current favorite solution is the Sennheiser AMBEO 1st Order Ambisonics mic. Read on to find out why the AMBEO is our go-to mic for projects all over the world.

Sennheiser AMBEO on location in Iceland

Why Sennheiser AMBEO?

Flexibility

We wanted the ability to deliver B-Format for immersive media, 5.1 or 7.1.4 for post, and stereo for YouTubers.  The Sennheiser AMBEO allows us to bring one mic and generate all of these assets without complicated (and heavy) mic bars, multiple stands, careful measurements etc. We’ve recorded in different surround formats over the years and AMBEO is the only thing portable enough for the tough locations we tend to record.

Sound quality

We’re very happy with AMBEO’s sound quality.  Low end power and high end details are equally well preserved.  Upon properly decoding to 7.1.4, the surround image is immersive and accurate.  Peers that have tried other Ambisonic mics are consistently impressed with what we get from the AMBEO.

Build quality

This is the big one! Sennheiser microphones are unmatched when it comes to harsh conditions. We’ve exposed our trusty AMBEO to some incredibly dangerous conditions over the years.  From the Florida Everglades in the summer to northern Iceland in a blizzard to literally being dumped on by a waterfall in Australia, it has held up beyond all reasonable expectations, oftentimes stuffed in a backpack or hand-carried out in the elements. On a recent trip to Northern California, a rogue wave knocked the entire stand, mic and all, into the Pacific Ocean. And yet the AMBEO survives. It is the undisputed Die Hard John McClane of microphones.

Jason setting up an AMBEO with Cinela Wind Protection in Thorsmork, Iceland

Recommended Accessories

12-Pin Extension Cable - 3 meter

The 12-pin to 4x XLR fanout cable is a sensitive spot in the setup.  I find the fanout cable to be susceptible to a high amount of handling noise.  The best way to avoid this is keep the fanout completely within the sound bag, which means you will need a long enough 12-pin extension to connect to the mic, run down the stand, and into the bag.

Cinela Piani AMBEO Windshield Kit

This product was a game changer for us!  The wind noise reduction is unbelievable.  It handles near gale-force winds with ease.  We pushed it to its limits (and a little beyond) in Iceland and I was honestly amazed at where that limit is.  The shockmount is incredible and the connbox eliminates virtually all handling noise.  Pricey, but worth every bit.  Also, be sure to check out the Piani Kelly Rain Cover.  We confidently recorded behind waterfalls and exposed in the rain knowing that the mic would be protected and the sound quality would be preserved.

Sound Devices MixPre 6 II

The perfect companion for the AMBEO.  The sound quality is impeccable and the Ambisonics plugin makes recording as easy as possible.  Direct conversion to B-Format saves a ton of time in post.  Linking the gain for all four inputs ensures good imaging.  Binaural monitoring gives us the confidence we need in the field.  It doesn’t hurt that it’s also extremely tough.

Some of the best tools for mastering Ambisonics

Mastering Ambisonics

I’ve read some complaints in message boards about first-order Ambisonic recordings' ability to form a stable, immersive, multichannel image.  I believe that with careful mastering it is possible to achieve excellent results!  I’m currently decoding 1OA recordings to 7.1.4 and loving it. However, utmost care must be taken in the mastering process. Here are some things I’ve worked out through hard-fought trial and error:

First rule of Ambisonics!

Make sure you are keeping track of whether your B-Format is set to FuMa or AmbiX. It’s very easy to get this wrong and it will make the immersive image fall apart if your plugins are set to receive the wrong input type. AmbiX seems to be the more widely used flavor of B-Format and most plugins will default to that BUT ALWAYS CHECK!

Upscaling

The Audio Brewers ab Upscaler plugin is pure magic. It can take a 1st Order Ambisonics recording from the AMBEO (or any other 1OA mic) and upscale it all the way up to 7th order! The gains in spatial resolution are astounding. As a rule, I am highly skeptical of anything that claims to enhance an existing recording but Alejandro at Audio Brewers has figured out a way to do it in a simply breathtaking manner. Lately, I’ve been going up to 3rd Order (anything more and the number of channels gets a bit unwieldy) before decoding to my desired monitoring format. Just be sure to do any EQ or other processing BEFORE the Upscaler exponentially increases the number of channels!

Decoding

I use Audio Brewers ab HOA Decoder for decoding B-Format down to stereo, 5.1 or even 7.1.4. It is an amazing tool, but there are some important things to consider.  First, be sure to monitor in whatever format you are decoding to.  This will require that you do separate passes for the 7.1.4, 5.1 and 2.0 versions.  Do not assume that the settings for one decode will work for the other.  They often don’t!  Next, be sure to rotate the image all the way around to make sure you’re achieving balance and focus.  Despite my best efforts at mic setup, I rarely use zero degrees for the optimal ‘viewing’ angle.  Finally, don’t be afraid to mess with the mic spacing angle, especially in the stereo render.  Don’t be dogmatic - sticking to tried and true stereo miking methods - the best sounding result may be something unexpected.

EQ

I use Fabfilter Pro-Q3 for EQ duties.  First, it supports multi-channel formats, which rules out many other EQ plugins (however, it will not support 1OA except in multi-mono mode - please fix that Fabfilter!).  Next, it is a phase linear EQ, so it won’t mess with the time alignment of the 4 channels - very important if you want to preserve that immersiveness!  Finally, it has a dynamic EQ function which is essential.  I like to use a low shelf EQ set to dynamic mode to take care of intermittent bursts of low energy (like in wind or wave recordings) without sucking all the low end power out of the rest of the recording.  AMBEO-specific tip:  I find that the AMBEO has some buildup in the mid-500Hz range.  I like to scoop out 3dB in this area to compensate.  Be sure to use a light touch and listen carefully.  If your EQ notch is too narrow or too deep some negative artifacts will be introduced.  Never apply EQ without good reason and be mindful of the how and why.

Noise Reduction

I use iZotope RX for light noise reduction.  Rule number one - never apply broadband noise reduction to an Ambisonic recording!  There’s no quicker way to add artifacts, chirps, swirliness - whatever you want to call it.  I limit my RX use to a few surgical functions when performing Ambisonic mastering.  First, Spectral Repair, set to a conservative setting, can remove unwanted birds, ticks, clicks, pops and so on.  Don’t expect it to completely remove every unwanted sound.  You may have to concede that an unwanted sound will remain slightly audible or you may need to cut around it.  Listen carefully and LOOK carefully.  If Spectral Repair is cutting a hole in your spectrum, discerning ears will notice!  I also use De-Plosive to take care of intense low-end energy.  Be sure to set the frequency threshold based on the source material.  Avoid the temptation to use De-Wind.  It’s designed to remove wind noise from voice recordings - not wind recordings!  It will leave musical artifacts all over the place near the cutoff frequency, which is tolerable in location dialog, but never in a nature recording!

Sennheiser AMBEO on location Mendocino County, CA

In Conclusion

The Sennheiser AMBEO is a workhorse. Ambisonics recordings are underrated. Mic drop (don’t worry, it won’t break).

Check out our immersive ambience libraries or hire us for your next field recording expedition.