Recording a Polyphonic Choir Arranged in Line with the Spaced Technique 

The Spaziata technique is one of the main recording techniques, also renowned for capturing the sound of a polyphonic choir arranged in a straight line, the most used during the recording of live concerts due to its better scenic usability compared to other techniques.

There are other recording techniques that may be more appropriate for choirs arranged in a semicircle or in a line, such as the XY, ORTF, corolla technique, and Blumlein technique. These techniques offer versatile solutions for different choral configurations and recording environments.

To learn more about these and other details about choral recording, I invite you to consult my new manual:

“Recording Polyphonic Choirs with Ease: A Manual of Professional Techniques Treated Simply for Choir Directors and Aspiring Sound Engineers”, available on Amazon, Apple Books and directly on this site with a discount of 25%.

Also see other Audio and Music manuals at the following link: Books and Manuals

Here's how to use the Spaced Technique to record your polyphonic choir:

Spaced Technique 

Optimized multiple directional recording of choir groups with spaced, non-phase technique.

Recommended placements for the Choir

The Spaced Record is ideal for choirs arranged in a line on a single level or up to 3 superimposed levels, with a front 2 meters wide or more.

It is almost always advisable instead of the ORTF technique, in particular, when the recording front (i.e. the choir line) exceeds 3 metres in highly reverberant locations and 4 metres in those with moderate reverberation.

It can also be used successfully with a choir arranged in a wide semicircle (crescent moon shape).

Microphones to Use

Use cardioid microphones (or with variable polar patterns set as cardioid), 1 microphone for each group of 3 singers arranged on the baseline.

Microphone Arrangement

Place the microphones in a line, each in front of a group of three backing singers, keeping the microphones exactly 150 cm apart from each other to ensure a consistent recording and optimize phase coherence. The three backing singers, positioned shoulder to shoulder, should be well-centered in front of the microphone.

Advantages

The spaced technique, if optimized correctly, offers good sound coverage for choirs arranged in a line, allowing for a balanced recording, a wide stereo image and a good possibility of managing the microphone volumes in post-production during mixing (and therefore also of the choir sections).

PRO

• Homogeneity: If done well, ensuring uniform coverage for all choristers.
• Versatility: It can be used with choirs arranged in a single or multi-level line.
• Environmental Reverberation Control: Significantly reduces the incidence of reverberation if microphones and backing vocals are positioned correctly.
• Stage Usability for Live Recordings: if you use small cardioid stylus condenser microphones supported by not too bulky stands, the scenic impact of the microphones will not be too invasive, on the other hand this technique is the best for capturing a choir in line, which is the classic and ideal positioning for the scenic needs of concerts.

AGAINST

• TimingThe technique does not allow for perfect phasing, but optimising the distance between the microphones allows for improved phase coherence, thanks to the 2.5:1 ratio between the mutual distance between adjacent microphones (150 cm) and that between the microphone and the backing singers (60 cm).
• Naturalness: It may not offer the same naturalness as other phased techniques such as Blumlein, ORTF or XY.
• Ease of useThis is a more complex technique that will require more time and attention to set up the positions of the backing singers and microphones correctly, which is essential for an optimal result.

Criteria for the spaced shot of a choir arranged in line

In this case, we are dealing with an out-of-phase recovery and therefore we must try to optimize it.

The technique involves an arrangement of various microphones aligned in front of the choir, in variable numbers according to the number of choristers involved

The phonic rule states that phase optimization is considered fully satisfied when the distance between one microphone and another adjacent one is at least 3 times the distance of a microphone from the sound source to be recorded, and is sufficiently satisfied when this ratio is at least 2:1. With 3:1, in fact, a reduction of approximately 89% of the direct out-of-phase sound is achieved, while with 2:1 this reduction is 75%.

With the method suggested here, the ratio is nearly optimal, at 2.5:1, with the 84% reducing approximately the direct out-of-phase sound.

With the above in mind, here are the instructions for precise positioning of the singers and microphones.

Number of Microphones: Calculate the number of microphones needed by dividing the total number of singers by 3. Add a microphone if there are 1 or 2 extra singers (not divisible by 3). Therefore, consider that you will need 4 microphones for 12 singers, 6 microphones for 18 singers, and 8 microphones for 24 singers, without prejudice to the possibility of distributing the singers across multiple levels (see below), thus saving on the number of microphones needed.

Distance between Microphones: Maintain a distance of 150 cm between adjacent microphones to avoid phase problems.

Positioning of the Choristers: Assign three back-to-back singers to each microphone. Each singer must have their mouth 60 cm from their microphone, so the two side singers in each trio must stand approximately 15 cm above the central singer and point their mouths toward the microphone. The microphone should be positioned upright or slightly slanted; for recording during a concert, it is acceptable (as a compromise) to point the microphone downward toward the soloists' mouths, so as not to visually invade the soloists' faces. This arrangement, if followed precisely, will ensure maximum uniformity of recording for all singers and minimize the penetration of ambient reverberation into the microphones. (PLEASE STUDY THE FIGURE BELOW CAREFULLY) 

Spaced Technique Choir – Alessandro Fois & Friends' Blog – alessandrofois.com

Diagram of a lineup of 18 choristers arranged in a 9-meter-long line, filmed with 6 microphones (1 for every 3 choristers). Note the 60 cm distance between each microphone and each chorister (obtained by placing 15 cm further than the lateral choristers of each trio) and the 150 cm distance between each microphone (a ratio of 2.5:1 between the distance between the microphones and the distance of a microphone from the choristers).

Management of Advanced Choristers: If, when counting groups of three singers per microphone, one singer is left over, position him as if he were the central singer of a group of three, that is, centrally in front of the microphone, 60 cm away, as with the others. If two singers are left over, position them together, shoulder to shoulder, instead of a group of three, centrally in front of the microphone, 60 cm away.

The resumption of the choir in line arranged on multiple levels

If you have a larger number of singers, you will need to equip yourself with more microphones and a higher number of input channels on the sound card, or you will need to distribute the singers on multiple levels, one behind the other, so as to always maintain a baseline of 3 singers for each microphone.

In fact, in height, the pickup angle of a microphone will be able to correctly handle up to 3 levels of overlapping backing vocalists (the trick will offer better results if the rear levels are gradually raised by means of a modular multi-level platform).

You will then assign to each microphone:

• 3 choristers on 1 level
• 6 choristers on 2 levels 
• 9 choristers on 3 levels

Therefore, with 8 microphones, appropriately arranged side by side in line at a mutual distance of 150 cm, you will be able to manage up to a maximum of 72 choristers, assigning each microphone 3 choristers x 3 levels = 9 choristers. 

Use microphone stands capable of good elevation (make sure they are stable) and always point the microphones from the front but raising them a little to direct them towards the midpoint of the 2 or 3 levels.

Finally, make sure that the distance between the mouths of the choristers of the entire group and the microphones does not exceed the maximum measurement of 70-75 cm.

Some notes

It's possible to use fewer microphones, assigning, for example, 4, 5, 6, or 7 to each backing vocalist on the baseline. This will require moving the microphones further away from the backing vocalist to capture them all evenly, and consequently, spacing the microphones to match the 3:1 ratio between the distance between the microphones and the backing vocalist, which is essential for proper phase coherence. It's therefore possible that an empty space will be created between one group and another. This will greatly increase the penetration of reverberation compared to the direct sound, even quadrupling with 6 or 7 backing vocalist per microphone on the baseline.