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Classical Music: a Walkthrough of Recording, Mixing, and Mastering an Album

by Jett Galindo, iZotope Contributor July 22, 2019
Los Angeles-based choral ensemble, Tonality, recording their album entitled “Sing About It”

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Part 1 of this article covered the fundamentals of classical music production—from recording and editing, all the way to mixing and mastering. We also covered the many elements that set classical music apart from a modern-style production.

In Part 2 of our classical music exploration, we get an inside look at how a recent choral album came to life, featuring Los Angeles-based choral ensemble, Tonality, and their album entitled Sing About It. Conducted by Dr. Alexander Lloyd Blake and produced by GRAMMY-winning classical producer Peter Rutenberg, they will be providing valuable insight into the production process of the album throughout the article.

The crucial pre-production stage: Do your research

Even before recording a choral album, it helps to know as much as you can about the music you’ll be working on. Communicate. Seek out all the information you need from the conductor and producers involved. This information, more often than not, will help steer you toward the ideal direction when planning the album production process. Conductor and music director, Dr. Alexander Blake, gives us the background on the album below.

Sing About It is an album comprised of musical compositions that relate to issues of social justice. Topics such as immigration, gun violence, police brutality, and abortion are presented within this album as a musical reflection and response to the socio-political climate of our time. I thought Sing About It should be produced because the issues covered on the album are relevant and urgent, and I wanted this album to be an example of how, we as choral artists, could use our voices to speak on these issues.”

The crucial pre-production stage: Do your research.

Musical programming

Tonality, lives by the music it sings, promoting the awareness of social justice issues in every musical performance. For the programming of their debut album, Tonality chose to collaborate with young composers and arrangers as they curate a selection of music that speaks to the issues of today.

With this in mind, you can already get the sense that this album doesn’t necessarily fit the conventions of a typical classical recording. Even with a standard choral ensemble setup, the selection of music ranges from gospel to contemporary classical with room for experimentation and creativity.

Choosing the recording location

As mentioned in Part 1 of this article, the right location is essential. Producer Peter Rutenberg explains in detail the virtues of choosing the ideal recording venue.

“An excellent venue must be chosen, not only for its great acoustics, but for isolation from external noises that interrupt the process with delays. These not only waste time, but frustrate the singers who then lose focus. A room within a room is ideal—for example, a chapel in the center of a complex with no exterior walls. At the very least, windows and doors should provide adequate isolation and be as far away from environmental intrusions as possible. The occasional plane or siren can’t be avoided. A busy street with traffic at all hours should be rejected.”

Acoustics makes up a significant part, not only of the overall sound, but also of the performance of every choral singer.

The acoustics make up a significant part, not only of the overall sound, but also of the performance of every choral singer. Besides making sure that external noises aren’t an issue with a particular location, I also make it a point to suggest that the music director choose a location where they would want to perform a concert. That’s typically a reliable way to gauge the suitability of a recording location.

Having recorded Tonality in previous projects using the conventional on-location setup, one of the questions that arose during the planning stage was whether to retain this familiar setup or explore potential alternatives. Having access to the UCLA Herb Alpert School of Music’s new recording studio—which was built from the ground up with classical music in mind—Tonality decided to proceed in this direction. 

Although the UCLA recording studio doesn’t have the same acoustics as a church or concert hall, its live environment makes it suitable for classical performances. It also removes external noises from the equation. And being outfitted with state-of-the-art microphones, a large-format console, and a Pro Tools HD DAW, there was room to explore creative recording techniques.

Performance preparation

A good choral recording is only possible if the musicians come in to the session well-prepared, both musically and technically. This might seem like a given, but I’ve been in sessions where note-learning still happens on the day of the recording. Not only does this eat up valuable recording time, but this also distracts from the focus of fellow musicians during the session, therefore affecting the overall well-being and sound of the entire ensemble. Rehearsals are a must before the recording session. Fortunately for Tonality, the music selected for Sing About It are familiar pieces from the previous choral season:

“We chose works for the album from selections we performed during our 2017–2018 season. Some of the works, such as the compositions dealing with gun violence and peace, were performed as a part of our concert titled “Put Your Guns Down”, a concert we have (unfortunately) repeated several times as gun violence continues to wreak havoc on our country. 

For each of the recording sessions, we held a rehearsal to rehearse the compositions and to hone in on the specific interpretations of each work. Due to this work and the familiarity of the selected songs, the process was smoother than I would have imagined,” shares Dr. Blake.

The rehearsals are also the ideal time for the engineer, producer, and conductor to strategize how each piece will be broken off into different sections for recording purposes. This is also a good time for the producer to take notes of difficult spots that might need extra attention during the recording session.

Recording Sing About It

As is typical with classical/choral recordings, the recording setup is kept to a minimum. Working with UCLA’s in-house recording engineer Stuart Schenk, we devised a setup utilizing a stereo ORTF configuration for the main choir mics. This stereo mic pairing is positioned strategically, several meters away from the choir, so it captures the ensemble as one entity, keeping in mind the optimal stereo imaging of the sound source. Four overhead condenser microphones are placed closer to the ensemble as supporting spot mics, and a separate condenser mic is set up for soloists only when necessary.

Tonality recording session at the UCLA Herb Alpert School of Music recording studio

Despite being in a recording studio, the goal was to simulate as much of the location recording experience as possible. Headphones and click tracks were not used (except for one a cappella track), and the ensemble’s performance strictly relied on the conductor as is typical in a live performance. It’s also crucial to achieve the ideal blending of the voices within a section (i.e., soprano, alto, tenor, bass) and the overall balance of all these sections into one organic, unified sound. Hence, the conductor might make balancing decisions on how the singers are arranged to make sure the ideal blend of the ensemble is achieved even before the mixing stage begins.

Maintaining the singers’ stamina

Recording sessions can take their toll on musicians, especially singers—whose instrument (the vocal cords) needs more rest in between performances in order to regain stamina. It’s important to keep this in mind for choral recording sessions.

Rather than performing every piece from beginning to end multiple times, it’s much more efficient to do a full performance once. Then, you record by section afterwards, keeping it to three takes per section, at the maximum. It’s also important to schedule short breaks for the singers after every recorded song. Water and refreshments must also be available for the singers to preserve vocal health and longevity, and to ensure that their performance doesn’t get compromised by the end of the day.

The singers' vocal health and well-being throughout the recording session should be top priority.

And especially for the theme of this album (Sing About It covers heavy social issues ranging from gun violence to police brutality), extra care was put into making sure the singers were in the right mindset while performing every piece:

“One of our singers, Stefanie Moore, gave an amazing speech about how we needed to say “yes” with our voices but also with our hearts. It helped to unite the intention in the room and the collective spirit. Throughout the sessions, singers gave personal thoughts and reactions to the sounds we were making and I think that kept us grounded and connected,” says Dr. Blake.

The role of the session producer

Finally, one key element in the recording session that shouldn’t be taken for granted is the presence of a producer. Peter Rutenberg explains why:

“One must hire a producer who has a full vision of the end product before the first note is laid down, in whom a conductor will put the full trust for realizing the final product. In effect, the conductor and producer share creative control for any recording. It doesn’t actually matter what the conductor “hears” live, only what is being recorded in the booth. Moreover, the conductor’s job is to anticipate and cue every musical event. Stopping to listen or react in real time in the middle of a take is counterproductive. Only the producer hears what is actually being recorded.”

With the conductor and engineer focused on their respective tasks during the recording session, keeping an eye (and ear) on the quality of the performance must be left in the trusted hands of a dedicated session producer—someone who can hear with discernment and help manage the session. Not having one leaves this crucial responsibility unchecked, or at least in the hands of the conductor and engineer, which eventually compromises their focus on the primary tasks at hand. In Peter Rutenberg’s absence, acclaimed choral singer and composer Saunder Choi took on this role for Tonality’s two-day recording session.

Tonality 'Sing About It' Production Team: From Left to right, Dr. Alexander Blake (Conductor), Peter Rutenberg (Producer), Saunder Choi (Producer), Kristen Simpson (Assistant Producer)

The editing stage

Before you head on to the mixing stage, make sure that you’ve set aside a generous amount of time for listening to the raw takes and vocal editing. For the Tonality album, Dr. Blake, Saunder Choi, and assistant producer, Dr. Kristen Simpson, each had their own listening sessions while keeping notes on the best takes on a collaborative Google Doc file. After completing the first round of listening with the timestamps on the best takes for every song, I then edited together the best performance from each take and spliced them into one full performance.

The editing stage doesn’t end there just yet. After the initial round of edits, the producers begin to take on a more heightened sense of hearing. We begin to pay attention to more nuanced details in the performance—one singer in the whole ensemble might have sung the wrong note, the onset of a great performance might not have sounded as tight, the basses might have sounded better on a different take, etc. With this in mind, expect to go through multiple rounds of editing with the producers. Tonality’s Sing About It took over two months to edit 14 songs.

“Poor Wayfaring Stranger” session after multiple rounds of editing

As the engineer, it takes practice and patience to master the art of splicing different takes. For a choral recording, a good rule of thumb is to take advantage of the different crossfade shapes on your DAW to help seamlessly ease in the transition from one take to the next.

Noise reduction with iZotope RX

As mentioned in Part 1 of the article, relying on a noise reduction tool becomes inevitable with choral music. When recording on location, outside noise might get in the way of a perfect choral performance. And, when working with a large ensemble, you’re bound to deal with noise from body movements. RX has proven numerous times how it can tackle the toughest noise in an audio signal. However, there are unique uses for RX 7 in the world of choral music—lining up sibilance and vocal plosives.

In this example from the Sing About It session, the song “Eye for Eye” had issues with a messy sibilance that happens in a particularly climactic section of the performance. The scattered esses distract from the impact of the dynamic swell that the choir has expertly sung.

Below is an audio clip of the performance with the sibilance problem that begins at the six-second mark (on the word “feast”):

Before RX

EFE

To address this, I loaded RX Connect from my DAW to access its full range of noise reduction tools right inside my editing session. A new, highly valuable feature in RX 7 that many classical engineers and producers would benefit from is the new multichannel support. From my DAW, I was able to select all eight individual channels and load them up on RX 7 instantly. After listening to the audio clip, you can quickly spot in the screenshot below where the fix needs to be done.

Multichannel editing in RX 7

To address this fix, I used RX 7’s Time-Frequency selection tool to select the targeted sibilant section. Using Spectral Repair’s Attenuate function with more analysis weight set to “Before”, I was able to clean up the rogue sibilance enough that you can hardly hear it in the performance. 

Cleaned sibilant section after the RX treatment

Listen to the same “Eye for Eye” performance but with sibilance cleaned up with iZotope RX:

After RX

EFE

For context, you can hear the full performance of “Eye for Eye” below:

Song: Eye for Eye

Composer: Shawn Kirchner

Mixing Sing About It

Now that we’ve edited together the various takes into one cohesive, exciting, and consistent musical performance, it’s now time to balance the various levels and colors into one unified sound through mixing.

As discussed in Part 1, mixing classical music is less about manipulating and processing recorded audio into an entirely new sound. Rather, you’re focusing on enhancing this recorded performance, allowing it to be heard in commercial playback systems as if you’re experiencing the same performance live. It takes experience and disciplined ears to fully grasp the nuances of mixing classical music, and we had the privilege of having seasoned classical producer, Peter Rutenberg, onboard for this stage of the album production. Though there are 16 songs total on the album, let’s focus on one song as a mixing example. 

Song: Poor Wayfaring Stranger

Arranger: Dr. Alexander Lloyd Blake

Soloist: Gabrielle Thompson & Stefanie Moore

“Poor Wayfaring Stranger” is an arrangement of an American folk song Dr. Blake created for Tonality’s “Stories of Home” concert that focused on homelessness, displacement, and immigration. With the message being the center point of Sing About It, it’s important that the mixing approach doesn’t only focus on the sonics, but also on making sure that the message comes across and doesn’t get lost in the aesthetics. 

Listen to an audio clip of “Poor Wayfaring Stranger” without any mix treatment:

Before Mix

PWS

Without any mix treatment, the performance sounds pleasing enough, but there are several things that do need further enhancement. One common EQ adjustment in the choral world is providing added support in the bass section. The female voice, particularly the sopranos, lies in the neighborhood of frequencies to which the ear is most sensitive. In contrast, the lower fundamental frequencies of male voices tend to get drowned out easily in ensemble performance, more so when picked up by microphones placed farther from the choir. The song “Poor Wayfaring Stranger” also particularly relies on a pulsing melodic line from the bass section, so an EQ boost in the low end is imperative.

The recording also needs clarity overall—an added boost of air at the end, above the soprano’s fundamental frequency, for the much-needed presence which also aids in the articulation of the words in the song.

The screenshot below provides a general overview of my EQ settings across the board. The main stereo ORTF tracks, which are labeled as the “Room Mics”, only needed a boost at the top end. The spot mics, however, I relied on for the added articulation in both the bottom and top frequencies.

“Poor Wayfaring Stranger” EQ settings (Left: room mics; Right: spot mic)

In addition, thoughtfully addressing the wide dynamic range of classical music is key. You don’t want to kill the natural dynamics in choral music, yet you also want the healthy balance of achieving clarity and impact in the world of commercial playback systems with limited headroom. That’s one of the common challenges engineers face when bringing classical music to the recorded medium. For the Sing About It album, a subtle amount of compression using the Ozone 8 Vintage Compressor on the individual tracks helped in achieving that clarity and impact.

“Poor Wayfaring Stranger” compressor settings

Listen to the audio clip of “Poor Wayfaring Stranger” after applying EQ and compression:

After Mix

PWS

One thing we’ve yet to cover at this stage is the use of reverb. When choosing a recording location for choral music, the venue’s acoustics become an integral part of the ensemble. Additional reverb is hardly ever used in the mixing and mastering stage.

In the case of Sing About It, being recorded in the UCLA recording studio, a touch of great-sounding reverb added in the mixing stage helped enhance the sound of the choral performance overall. We were fortunate that the studio was equipped with the Bricasti M7 reverb hardware which I utilized during the session for use at the mix stage. However, after the additional mix treatments, an added layer of reverb was necessary to add depth and space to the music. Exponential Audio’s PhoenixVerb plug-in is excellent when it comes to providing lush, organic-sounding reverb that’s perfect for classical music.

For “Poor Wayfaring Stranger”, I started by choosing the Large Chamber preset, then fine-tuned its taste. You’ll also notice on the mix session below that we automated the level of the PhoenixVerb. This is for times when the arrangement gets denser, thus needing less of the extra reverb in the mix.

Exponential Audio’s PhoenixVerb plug-in is excellent when it comes to providing lush, organic-sounding reverb that’s perfect for classical music.

Now, let’s listen to “Poor Wayfaring Stranger” with the added reverb. It’s subtle, but it makes a lot of difference, particularly during the verses.

After Mix with Reverb

PWS

Mastering Sing About It

Before moving on to the mastering stage, it’s especially important to be able to take a step back and establish the roles that distinguish what a mastering engineer is versus a mixer. iZotope came out with an excellent article recently about the many ways to strategize mastering records that you’ve mixed yourself. And in the world of classical music, it’s not that much different. 

For the Tonality album, one strategy I relied on to make sure my mixing didn’t influence my mastering ears was not to work on my dedicated mastering station at The Bakery. I mixed in-the-box at home with my personal laptop. The one exception to taking my mixes at The Bakery is when I’m working on mix revisions with the producer, Peter Rutenberg, and conductor, Dr. Alexander Blake. Regardless, this strategy has helped me keep my listening perspective in check. Furthermore, taking a week’s break from listening to the album has also helped me immensely in preparing to take the driver’s seat at the mastering stage.

Keep in mind that with mastering, adjustments become more nuanced and the increments are significantly smaller. Oftentimes, a single dB of boost can really make a subtle difference, so critical listening is key.

For “Poor Wayfaring Stranger,” listening at The Bakery confirmed that it needed just a tad bit more warmth in the low end and support in the subharmonics. Using the low-shelf EQ with a wide bandwidth, I added a subtle amount of warmth and weight that complemented the needs of the song.

Poor Wayfaring Stranger mastering EQ settings

With the music needing a bit more support helping its natural impact and clarity translate in a world of limited headroom, I relied on the transparent sound of the Ozone 8 Vintage Compressor once again, this time with the ratio set to 1.5:1 for a more subtle effect. Keeping the compressor in Balanced mode helps preserve our natural dynamics while enhancing the overall body of the song.

Poor Wayfaring Stranger mastering compressor settings

Once it reaches The Bakery’s analog console, I simply relied on our tube line amps to provide added gain to our masters—no other outboard processing required. Once it reaches our SADiE mastering DAW, I utilized Ozone's Maximizer set to IRC III Balanced mode. Sliding the Character setting closer to Slow allows for a more natural attack/release limiter response time, which is ideal for a choral performance. I love using Ozone 8 for classical music overall, but applying this particular setting does wonders for choral music. At the end of the day, however, always listen for the particular needs of the music you’re working with.

Poor Wayfaring Stranger mastering limiter settings

You can listen to the “Poor Wayfaring Stranger” master and the whole Sing About It album here.

Now that you’ve gotten a glimpse of an actual choral album production from start to finish, Part 3 continues with you! Technically, there’s no “Part 3” to this article, but what I mean by that is, the only way to instill all these techniques to achieve a great-sounding choral album is by going out there and getting your hands dirty and learning from experience. Start by collaborating with classical and choral musicians from your local community—your school, church, etc. There is always a need for engineers to bring their music to life, so there’s no lack of opportunities to learn and sharpen your skills.

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