For Norwegian engineer, producer and record label boss Morten Lindberg, immersive audio begins at source.
The title of this series is only partly applicable to Morten Lindberg. The Norwegian engineer, producer and record label boss is undeniably a specialist in Atmos — but there’s no mixing involved. Instead, Lindberg aims to make immersive multichannel recordings that can be played back directly on a 3D speaker setup with no additional balancing or processing. It’s a logical extension of the purist ‘straight to stereo’ approach that is favoured by many audiophiles; and since every stage of the process from recording to release is under Lindberg’s control, there is no external pressure to do things differently.
“I started out as a recording engineer back in the early ’90s, working mainly with classical, traditional folk and jazz music. Anything sounding in a natural acoustic environment was on my radar. Norway has never had any industrialised music production with the strictly compartmentalised craft categories, so it was only natural for me to expand to a more holistic approach to the phonographic art. As music producer I now participate in the process from conception through production into communication of the final product to the consumers. Initiating 2L as a music label was a natural development.
Lindberg aims to make immersive multichannel recordings that can be played back directly on a 3D speaker setup with no additional balancing or processing.
“We started out as a production company in the early 1990s, but as the major labels scaled back their classical music recordings, we wanted to move forward. Our obvious solution was to start our own label. We currently make 10 to 15 new releases per year, all on Hybrid SACD, Pure Audio Blu‑ray, downloads and streaming services. Most productions feature Nordic artists and contemporary composers, but also the classical European tradition. I believe our recordings and the way they sound make an impact because it comes from the heart and soul of everyone involved. We don’t speculate about what a commercial market might want to receive. We make what we would like to experience ourselves. That makes it personal.
“Our sonic image is created in the recording, with dedicated microphone techniques. I don’t spread as many microphones as possible for someone else to pull the faders in post‑production. I make my choice there and then, so I have a result that will serve the fundamentals of decisions to follow. The composers and musicians need to perform to the extended multidimensional sonic sculpture, allowing more details and broader strokes. Then immersive audio and surround sound is just a matter of opening up the faders.”
Morten Lindberg is emphatic that he is not trying to recreate the experience of being in the audience for a live performance. “All my work is dedicated recording sessions, and my role is both as an engineer and as a producer. This means I get to directly interact with the musicians with the sole purpose of creating the recording. Every project starts out by digging into the score and talking with the composer, if contemporary, and the musicians. It is not our task as producers and engineers to try to recreate a concert situation with all its commercial limitations. On the contrary, we should make the ideal out of the recording medium and create the strongest illusion, the sonic experience that emotionally moves the listener to a better place. The beauty of the recording arts is that there is no fixed formula and no blueprint. It all comes out of the music.
“There is no method available today to reproduce the exact perception of attending a live performance. That leaves us with the art of illusion when it comes to recording music. As recording engineers and producers, we need to do exactly the same as any good musician: interpret the music and the composer’s intentions, and adapt to the media where we perform. Immersive audio is a sculpture that you can literally move around and relate to spatially; surrounded by music, you can move about in the aural space and choose angles, vantage points and positions. Rather than reproducing a concert situation, we consider the recording art a discipline of its own. It gives us the possibility to place the listener in an ideal position and become an actual party to the event. Through a dedicated production of the music we can maximise energy, reveal all the small nuances and avoid distractions. The emotional impact can be made more massive than ever. The conductor’s position is the seat no audience can afford — until now, with these dedicated recordings.”
Maximising the energy and emotional impact of a recording frequently requires directing the musicians to perform differently from how they would in a concert. “All classical musicians are trained to project their sound all the 150 feet down the aisle of the concert hall. The first thing we do is to move us towards a more intimate communication with the listener. This type of sound‑making affects both texture, volume, timbre and articulation. Then volume is the next step. It’s the same with both singers and instrumentalists, but a string player is best for demonstration. The first 80 percent of added energy results in volume and enhanced dynamics in a musical sense, but adding further vertical power from the bow to the string only results in distortion and a shrill harshness. With this in mind, the musicians manage to produce a more beautiful sound for me to record.
“In those situations where I succeed with this approach also with a full symphony orchestra, magic occurs and the string players start pulling out their earplugs. Combating the acoustic loudness war makes all the difference in the world on how they control their own sound‑making.”
As you’d expect, the choice of location is also critical — but perhaps not for the reasons you might expect. “A really good recording should be able to bodily move the listener. This core quality of audio production is made by choosing the right venue for the repertoire, and balancing the image in the placement of microphones and musicians relative to each other in that venue.
“We often record in spacious acoustic venues: large concert halls, churches and cathedrals. This is actually where we can make the most intimate recordings. The qualities we seek in large rooms are not necessarily a big reverb, but openness due to the absence of close reflecting walls. Making an ambient and beautiful recording is the way of least resistance. Walking the fine line between direct contact and openness, that’s the real challenge!”
When making a straight‑to‑stereo recording, we have the option of using a coincident mic array or a spaced pair. Both approaches have their own technical strengths, but fundamentally, the choice is a subjective one. Some people prefer the pin‑sharp stereo imaging of Blumlein, others the lush and expansive quality of spaced omnis.
Similar options are available for surround recording, where the 360‑degree soundfield can be captured at a single point using an Ambisonic mic, or using a three‑dimensional spaced array. Morten Lindberg is a firm adherent of the latter approach. “The Ambisonic concept is a beautiful theory, and its application in VR is obvious. Early on, I experimented with a Soundfield microphone. The spatiality came out fine, but I never managed to capture that solid core of the instruments I was searching for.”
Consequently, recordings on Lindberg’s 2L label are made using a sophisticated cubic array containing two layers of omnidirectional mics, sometimes in conjunction with Acoustic Pressure Equaliser ‘spheres’ to increase directionality at high frequencies. “Our 2L Cube is only remotely inspired by [classic stereo techniques such as the] Decca or Mercury tree. The microphone array is really a direct consequence of the speaker configuration in the immersive playback systems. Time of arrival, SPL and on‑axis HF texture is directly preserved in this 7.1.4 microphone configuration. Proportions are cubical, and the dimensions could vary from 150cm for a large orchestral array down to 40cm in an intimate chamber musical context. In most projects I don’t use spot mics at all: only when there is a special purpose motivated by the score, like an imploding internal voice or an exaggerated outward dimension.
“I always use true omnidirectional microphones in the main array. Depending on the room, the music and the instruments, I alternate between the DPA 4003 and the 4041, the latter with the larger membrane providing a more focused on‑axis texture. My very first microphones were a matched pair of B&K 4003s, recording straight to DAT. Rather than exploring a wide range of makes and models I stayed with DPA and spent my time getting to know them intimately. To maximise the potential of the DPA High Voltage concept, we have a custom‑built power supply feeding 200V and 130V on 4‑ and 7‑pin XLR totally transparently to the microphones. All microphones go through the same type of mic pre and I know the sensitivity specs of each microphone model. My unity gain at recording is set to equal acoustic sensitivity for all microphones.
“My key to a good recording is to keep the signal path clean and short, with as few components as possible. A simple and pure signal path is the means to true high‑resolution audio, not only at recording, but also preserving the purity all through editing, mix and mastering. We record at 24‑bit, 352.8kHz and preserve this resolution all through into our distributed master files. There has been much focus on word length, but to me the sample rate is more important, as impulse response [which is captured and preserved more faithfully in a high‑resolution system with its better high‑frequency response] connects directly to our primal sonic perception on a subconscious level.”
Morten Lindberg avoids using any sort of post‑production processing that alters the sound: “The most important aspect of post‑production is to not destroy the fine qualities captured at recording. Instead of EQ in post, I much prefer to rather shift the angle or the distance of a microphone beforehand in recording. It just takes planning. With a good recording, I never use any EQ or dynamic processing at all.”
Instead, the focus of his post‑production efforts is on sympathetic editing to create what he feels is the most compelling realisation of the composition. “Editing is an important tool. It makes it possible to combine the highest level of energy and details into an intense performance. To do that you need to use a sonically transparent workstation. For the past decade we’ve worked with Merging Technologies on their Pyramix system. Their latest development allows for an immersive workflow totally independent of destination format. I don’t mix for a codec. I record for a playback environment. Any codec should then ideally provide for a transparent transport to the consumer.”
Morten Lindberg: "For the past decade we’ve worked with Merging Technologies on their Pyramix system. Their latest development allows for an immersive workflow totally independent of destination format."
A high‑quality monitoring environment is also necessary, and Morten Lindberg’s mixing space undoubtedly provides just that. “I wanted a critical listening room with no discrimination directionality, and with an extended ceiling height. A traditional listening room usually has a clear front‑to‑back development. For a true immersive experience, I wanted to extend the left‑right symmetry into a coherent surrounding field of reflections. The challenge then was to avoid the obvious square room mode, and the solution was to make an acoustic membrane allowing 150Hz and below to escape into the machine room as an absorption chamber. I considered the specifications from Atmos, Auro‑3D and the classic 5.1, and arrived at a hybrid positioning of the speakers that covers the three configurations pretty well. Lately I have also added the ‘wide front’ speakers for 9.1.4 and a second subwoofer in an asymmetrical position to smooth out room modes for the ‘point one’.
“Beside my own work, this room is used for critical listening and QC for a wide range of genres. From the sidelines, I would encourage all friends and colleagues to make considerate choices between phantom and hard centre [ie. panning sources directly to the centre speaker as opposed to generating a phantom centre image from the left and right speakers]. There’s a beauty to that lead vocal anchored into the centre speaker. I also observe a tendency to use the LFE as a general bass‑booster, replicating LF from main channels. This way of pre‑mixing what should be left to bass management in the end‑user environment is bound for trouble. Using LFE for dedicated musical components is way more effective to the extended experience.”
In theory, one of the key design features of modern immersive audio formats is scalability. The engineer should be able to supply a single master recording which gets intelligently adapted to suit any distribution format and listening system. However, Morten Lindberg deliberately does not do this, and feels that the fidelity of his recordings is fully preserved only by making dedicated masters that map each microphone directly onto a loudspeaker in the surround playback system. To achieve this in Atmos, for example, he places all the mics on the lower level of the 2L Cube directly into the 7.1 bed, and uses the objects only to route the upper layer of mics to the overhead loudspeakers.
Morten Lindberg: "Our philosophy is simple: one microphone straight to one speaker."
“Our philosophy is simple: one microphone straight to one speaker. For Auro‑3D or Dolby Atmos, all 7.1.4 microphones go directly to their according loudspeaker. With diminishing numbers of loudspeakers, we do not sum or fold down. We take away sources. So for 5.1 only the lower bed of microphones are active, without the side‑fills. Then it is usually only front left and right microphone playing in stereo, possibly with a slight texture added from the rear microphones. Pure, clean and minimalistic. The important aspect is to configure the array so time of arrival is captured and released in natural order.”
This scalability is also supposed to mean that Atmos masters can be experienced on headphones, with binaural processing keeping the sense of 3D spatialisation intact. Morten Lindberg doesn’t feel that this works well enough at present, and so prefers to direct headphone listeners to the stereo mic instead. “I have tried really hard to find a way for the single‑inventory file delivery to work on both speakers and headphones. But the tools currently available for headphone virtualisation from an ADM [the Atmos master format] are not yet sufficient. Waiting for implementation of more useful metadata instructions to be implemented, and respected by the services, my target is speaker playback. For now, my dedicated stereo mix sounds better on headphones than any binaural processing.”
One obvious challenge for anyone making immersive recordings on location is monitoring. It’s not usually feasible to set up a surround loudspeaker rig in an improvised, temporary control room. Through long experience, however, Morten Lindberg has learned to make the right decisions purely on the basis of headphone monitoring.
“On venue recording sessions, I find that headphones give me exactly the kind of information I need, which is what the microphone is picking up at its current position. You can do pretty much anything and have full control on headphones. I emphasise this because tradition says ‘You can’t record or mix on headphones.’ Yes, you can, but you need to relate it to a speaker environment by experience. Build a sense of transfer functionality, which makes you secure on headphones. You also must have a very good mastering studio so you can make the final production sound like it did while recording on headphones.
“I think one aspect of quality production is to step back and just relax and actually allow yourself time to experience what is really happening. Only then can you make the right choices on how to move forward. Stop, listen to what’s happening around you, reflect and then act.”