Your Complete Guide to the Decca Tree Mic Technique
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The Decca Tree microphone technique is a staple in the world of classical music recording. Originally developed in the 1950s by engineers at Decca Records, it has since become one of the most reliable and popular methods for orchestral recording with depth, clarity, and spatial realism.
This guide will walk you through everything you need to know about the Decca Tree, from its history to how it is set up, and will also address some frequently asked questions related to mic placement.
What is the Decca Microphone Technique?
The Decca Tree is a three-microphone array primarily designed for orchestral recording, though it can also be adapted for other types of ensemble performances. It consists of three omnidirectional microphones arranged in a triangular pattern. Said mics can have any polar pattern but the omnidirectional pattern is ideal. The main purpose of the Decca Tree setup is to capture a wide image of the performance while maintaining a strong central focus and a sense of depth.
In this configuration, two microphones are positioned around two meters apart from each other, known as the “left” and “right” mics. A third microphone called the “center” mic, is placed about 1.5 meters in front of the other two, forming a “T” shape pattern outlining a triangle. The spaced microphones are typically mounted on a large T-bar suspended above the conductor’s position or podium, roughly three meters above the ground. This height ensures that the mics capture a natural blend of instruments and the reverberant sounds from the concert hall or studio.
Who Created the Decca Microphone Technique?
The Decca Microphone Technique was created by engineers at Decca Records in the early 1950s. It was primarily developed by a team led by Arthur Haddy, Roy Wallace, and Kenneth Wilkinson. They first had to experiment with various techniques while maintaining mono compatibility until they eventually came up with the Decca Tree.
They designed the Decca Tree technique to achieve high-quality stereo recordings of orchestras, capturing both the instruments and the natural acoustics of the concert hall or studio. Their innovation became a standard in classical recording and the same technique is still widely used today.
Setting Up the Decca Tree
The key to the Decca Tree’s effectiveness lies in its ability to deliver a balanced and spacious stereo recording without losing focus on the main musical elements. Setting it up correctly requires careful consideration of distance, placement, and the type of microphones used.
First, you will need three omnidirectional microphones. Omnidirectional mics are preferred because they can pick up sounds uniformly from all directions, which is essential for capturing the full tonal range and spatial character of an orchestra. The microphones are placed on a T-bar rig, with the left and right mics spaced roughly two meters apart. In this regard, there are those who see this method as a variation of the spaced pair.
The center microphone is then positioned about 1.5 meters in front of the middle point between the left and right mics. This forward positioning helps to reinforce the central sound of the ensemble, preventing any instruments in the middle from sounding distant or lost.
The placement height is another critical factor. Typically, the Decca Tree is suspended three meters above the conductor, but this can vary depending on the venue and the desired sounds. For example, if you want to capture more of the hall’s acoustics, you might raise the rig higher, while lowering it slightly can produce a more intimate mix that one can audibly hear.
Why Use the Decca Tree?
The Decca Tree offers several advantages over other stereo recording techniques. For one, it provides a well-balanced and strong stereo image without compromising the sounds coming from the center of the orchestra. Many stereo techniques struggle to create a wide soundstage while keeping the central elements clear and detailed. The Decca Tree, however, manages to do both by utilizing the forward-facing center mic.
Moreover, this technique captures the natural ambiance of the concert hall, providing a rich and immersive listening experience. The omnidirectional microphones pick up not just the instruments but also the reflections and reverberations from the hall. This quality is what makes recordings using the Decca Tree feel so lifelike and dynamic. The sense of space and depth can transport listeners right into the concert hall and stage, making them feel as if they are attending a live performance.
Enhancing the Decca Tree Setup
Though the basic Decca Tree configuration involves three microphones, engineers sometimes add supplementary mics to enhance the overall mix. For instance, additional “outrigger” mics can be placed further to the left and right to expand the stereo imaging, capturing the outer edges of the orchestra. This method can be particularly useful for larger ensembles or when recording in very spacious venues.
There are also scenarios where spot mics are used. These are placed closer to individual sections of the orchestra, like strings, brass, or woodwinds, to bring out specific details. The signals from these spot mics are then blended with the main Decca Tree tracks during mixing, providing more control without losing the natural ambiance captured by the mic array.
Final Note
The classic Decca Tree setup remains one of the most respected and effective methods for recording orchestras and large ensembles. Its ability to deliver a wide yet balanced stereo image, coupled with a sense of natural space, makes it the go-to choice for classical producers.
By understanding how to set up and utilize this configuration, you can capture recordings that convey the grandeur and subtlety of live orchestral performances, ensuring that the essence of the mix reaches the listener with all its intended impact.
Frequently Asked Questions
What is the 3:1 rule for mic placement?
The 3:1 rule is a guideline that helps prevent phase interference when using multiple microphones. According to this rule, the distance between two microphones should be at least three times the distance from each mic to its direct sound source. For example, if a mic is one meter away from a violin, any other mic should be positioned at least three meters away from that violin.
This reduces the risk of phase cancellation, where two mics pick up the same sound but with slight timing differences, leading to a loss of audio quality. While not directly related to the Decca Tree, understanding the 3:1 rule can be useful when adding supplementary or spot mics to your setup.
What is the best mic technique for vocals?
The best microphone method for vocals depends on the style of music, the vocalist’s tone, and the recording environment. In most cases, a single, high-quality cardioid condenser microphone is used for lead vocals, positioned around six to twelve inches from the singer’s mouth. The mic is often slightly angled to avoid plosive sounds and to capture a natural sound.
For stereo recordings, a common setup is the XY method, where two cardioid mics are placed close together at a 90-degree angle. However, these methods are quite different from the Decca Tree, which is designed for recording ensemble performances such as a musical ensemble or larger groups rather than solo vocals.
What is the Blum mic technique?
The Blumlein is another stereo-recording technique, but it differs significantly from the Decca Tree. It uses two bidirectional (figure-8) microphones positioned at a 90-degree angle to each other, placed as close together as possible. This is ideal for recording the stereo image of a smaller ensemble, a solo performance, or even an acoustic environment.
Unlike the Decca Tree, which can handle the complex soundscape of an orchestra, the Blumlein excels in situations where a more focused and detailed stereo image is required. It captures both sounds and room reflections, resulting in a natural, immersive recording.
How do you achieve stereo recording?
Stereo recording is achieved by using two or more microphones to capture sound from different positions, creating a sense of width and depth. Techniques like AB, XY, and ORTF place the mics in specific arrangements to produce a natural stereo image, where the panned left and right channels replicate how a pair of human ears perceive sound.
What’s a good center microphone?
For setups like the Decca Tree, a single mono microphone may just not cut it. A good center stereo microphone for setups like the Decca Tree is an omnidirectional condenser mic, such as the Neumann m50 or DPA 4006. These mics are known for their wide frequency response and ability to capture both sound and room ambiance.
It’s also worth noting that the m50 microphones are what Decca Studios used in the original Decca Tree recording technique during the 1950s.
Where should a center mic be placed?
In a typical stereo pair or Decca Tree setup, the center mic should be positioned slightly forward of the left and right microphones. It is usually placed about 1.5 meters in front of the centerline between the other two mics, ensuring it captures the core sound of the ensemble without losing stereo width. This also ensures you can reduce crosstalk and excessive correlation at low frequencies.
With the spaced pair, two-spaced microphones, and a center-fill mic, you can achieve good localization and surround sound that’s worthy of film scoring. Listen to the mix through your speakers of a pair of good headphones, and you will know just what we’re talking about!
