Recording A Choir For An Atmos Mix

Photo: James Greenoff

Would your mic techniques change if you knew your location recordings were destined for a Dolby Atmos release? That’s a question our technical editor recently had to ponder...

Back in August last year, the film, TV and games music composer and producer Hilgrove Kenrick — who is a good friend — invited me to record a choir performing a dozen new compositions that he planned to release as four themed EPs in late 2025 and early 2026. Although I’ve written in SOS about choir recording sessions in various locations over the years, this one, which took place in early October 2025, was a little different — I knew in advance that the project would be released in the Dolby Atmos immersive format. That posed some interesting questions, and I thought it would be worth sharing how we went about answering them.

The Project

The performances would be by the 12‑strong SATB (Soprano, Alto, Tenor and Bass) choir, Ǣfendrēama, which was founded by Hilgrove and his wife Chloe (herself a composer and choral director), with a backbone of choristers from the UK’s Three Counties’ Cathedrals (Worcester, Hereford and Gloucester) augmented by friends and colleagues from the wider choral fraternity. The project was to feature several commissions that had been performed but not yet recorded, along with several brand‑new compositions that were ‘ready to go’, many of which crossed over in the Christian calendar and liturgy, notably Remembrance, Christmas and Easter. It made sense to record all of these pieces in one place on the same day, so as to make the most of our setting up time and facilitate a whole series of future releases. The scores for the day were prepared for the majority to view on iPads, by Andrea Possee — she also produced paper copies for a few Luddites, including me!

Location

Hilgrove has worked with various forms of surround sound for film and games over the years, but most commonly in 5.1. In 2024, though, he moved premises and, since the Atmos format is increasingly required on commissions, elected to install a 7.1.4 PMC speaker system in his new studio. Having already worked on several Dolby Atmos releases since then, it was only natural that he’d want a live location recording such as this to capture the acoustic space in such a way that it would translate into spatial audio for an Atmos mix. One significant benefit of working in Atmos, of course, is the ability to scale to different speaker arrays: mixing in 7.1.4 would allow for playback in bigger 9.1.6 rooms, down to binaural on platforms such as Apple Music, and anywhere in between.

After brainstorming some recording ideas over a pub lunch, we visited a few potential venues within a 50‑mile radius, and eventually decided to record in the Leominster Priory Church of St Peter and St Paul. With a vast Norman nave and a history that can be traced back to the seventh century, it’s an impressive building all round. But for us, its key strengths were a lovely acoustic, a location well away from any major roads and other environmental urban noise sources, and the ability to drive right up to the door for loading/unloading. There was also the fact that the church administrators were very flexible in accommodating the needs of the day — principally in closing the place to the public for the entire day, apart from an hour at lunchtime! The Priory also had a recently restored Nicholson pipe organ, with the added bonus that the company’s head organ voicer happened to be one of the choir’s tenors. On the day, he arrived for the recording, tool bag in hand, just in case of any last‑minute pipe tweaking requirements!

Load‑in & Rigging

With a venue and recording date secured, all that remained was to plan the load‑in and mic rigging, factoring in enough time for two three‑hour recording sessions, with breaks for the performers. We also had to sequence the musical pieces in a way that would give sections or soloists a rest between particularly challenging passages. The entire session would have to be rigged, optimised, recorded and derigged in a single 12‑hour day. Oh, and there’d be a photographer wandering around snapping promotional pics throughout, with the last 90 minutes of the day allocated to shooting videos of several pieces, too!

Hugh’s diagram of the performer positions and planned mic placement for this recording session.I like recording choirs, and not least because it can usually be done with minimal equipment. An eight‑channel recorder, along with a pair of headphones, and a few mics, stands and cables, is usually more than enough — that means only one trip from the car, which is my kind of load‑in these days! But of course, Hilgrove’s desire to record for an Atmos mix escalated the requirements considerably. While I’ve made plenty of surround‑sound recordings over the years too, using both Ambisonic mics and discrete 5.1 mic arrays, I’ve never recorded anything specifically with Atmos in mind. But how hard could it be?

Our outline plan was to arrive and be ready to start the load‑in at 08:00, and have the system rigged and ready for fine‑tuning by 09:30. The choir was scheduled to record from 10:00 to 13:00 and 14:00 to 17:00. The video shoot at the end wouldn’t need sound from me, so we could derig while that was happening, with the aim of being out of the door by 20:00, at the latest. Inevitably, those timings slipped a little on the day, and we recorded later into the evening than originally planned, but it all worked out well.

Mic Selection & Placement

As the recording deadline loomed, I worked out a technical plan for the microphone selection and placement and the associated gear we’d need for this substantial location recording session. Obviously, a big part of the sound of this recording was the building’s large‑scale acoustics, so lots of ambient miking (included dedicated height channels) would be required to create a diffuse and decorrelated ambient soundscape to spread across the multitude of Atmos speakers. It soon became clear that, although I have a lot of recording equipment, I’d be hard‑pushed to provide everything we’d need. So I asked another friend, classical recording engineer Steve Swinden, for help, and he lent me several high‑end mics, specialist stands, and other equipment, as well as scrounging more mics from a friend. He also volunteered to assist throughout the whole day — which was incredibly helpful!

The church housed a good organ, and it was used for accompaniment on these performances. Naturally, though, these instruments issue more noise than might sometimes be wanted when you’re mixing, so some processing of the recordings was required for the best result.

Most of the pieces were to be performed with an organ accompaniment, and the building’s Nicholson organ (NPOR N09762, restored 2016) is located at the East end of the South aisle, about 25 metres away from where the choir would be on the day, in front of the altar at the East end of the North aisle. Obviously, the organ sound would be picked up on all the mics to some extent, but I decided that close‑miking the organ would provide additional options in the mix, affording plenty of detail and focus, with nice stereo spreads of the pipework. The organ includes 32ft pipes in the pedal department, and the casework is open on both the North and West sides so, assuming the two sides of the organ might have noticeably different tonalities (depending on the registrations and departments in use), I decided that the option of spreading these different organ sounds anywhere within the Atmos mix could be useful — for example, as stereo spreads down both sides, or across the front and back, or even overhead!

Given the potential for very low frequencies and a desire to capture the organ within the nice Priory acoustic, I selected two pairs of Sennheiser MKH 20 omni mics, each pair being spaced around 66cm apart, and placed about 6m (roughly 6.5 yards) away from their respective sides of the organ. Manfrotto 154B mic bars supported the mics atop tall Manfrotto 269HDBU tripod stands, raised to be roughly level with the middle of the facing pipes.

I wouldn’t normally choose to close‑mic a choir, but I was concerned that diction might be lost given the great distances and large number of other mics involved, so I decided to rig eight mics in a line a couple of metresyards in front of the 12 choir members, using near‑spaced pairs to cover each of the three‑member SATB sections. The idea was that these could be used in the mix either as four stereo pairs, or as pan‑able mono mics, and could be balanced as needed — but this was conceived more as an insurance policy than to provide primary sound sources, and I don’t think they were used in the final mixes. These ‘accent’ mics were rigged on K&M 21021 stands with K&M 23550 stereo bars, and I used a variety of large‑diaphragm mics because most of my small diaphragm mics were allocated elsewhere in the rig! Hilgrove supplied a pair of...