Utilizing the right stereo recording technique is essential to developing an ideal stereophonic image.
A well-produced recording will effortlessly allow the listener to pinpoint the location of the performer.
The quality of the imaging depends on various factors. Keep on reading to learn more about different studio recording methods that will help you produce quality content.
A/B Stereo Recording
In this technique, you place two omnidirectional microphones, with small diaphragms, around 3 to 10 feet apart.
Also known as ‘spaced air,’ this technique creates a time difference that the brain perceives as a stereo image.
The acoustic delay in this technique must fall between 1.5-1.7 ms to create a full panorama feel. Any less than this will create a stereophonic image instead.
In the A/B recording method, you will use two parallel unidirectional mics. The microphones capture stereo information like the time of arrival.
You can also obtain a certain level of amplitude difference if you place the mics close to the sound source.
If you place the microphones at a distance of around 60 cm apart, the signal reaches the second mic approximately 1.5msec after it reaches the first one.
The range is ideal and will give a resultant pickup angle of 180 degrees.
If you increase the distance between the mics, you end up decreasing the pickup angle as well.
The technique is simple and easy to set up.
You can have the studio set up and can begin recording in minutes. It provides excellent frequency representation for even some difficult sounds like bass tones.
It allows you to capture the width, depth, and breadth quite adequately. This setup works particularly well when recording nature’s ambient sounds.
A significant drawback of the technique is that it does not work well in practice as it can create a comb filter-like effect.
The filter, while constructive in some recordings, may sound thoroughly unpleasant in others.
Since it is hard to control, it may not be the most desirable of recording methods.
The listener may also face trouble when attempting stereo separation in this format.
X/Y Stereo recording
In X/Y recording, you place two cardioid mics at an angle of around 90 to 135 degrees.
Usually, these microphones have small-diaphragm condensers and have their capsules touch each other at one point.
Since both capsules cannot be in the same position at the same time, you are technically placing them atop each other.
This placement represents an X like shape and provides extensive stereo coverage. The wider the angle, the greater the coverage you will receive.
If you want a recording method with a wide stereo range and minimal phase issues in close-mic applications, then this is the technique for you.
It will create narrow, crisp recordings that will feel more focused than real life.
It is a simple, easy to align method.
You do not require expensive equipment to set it up. It works particularly well in situations where you need the mono capability, which makes it a popular choice for close-range recording.
You can also use it for specific sound effects where you require a clear and stable stereo image.
It produces incredibly lively audio recordings. The stereo image it creates goes a long way in providing more immersive sounds.
However, you cannot utilize this technique to capture particular sounds or create stereo stage sound effects.
If you use cardioid mics, then the captured sound may lack bass and lose a substantial amount of frequency when played back in mono.
It is for these reasons that X/Y technique is limited to recording close range instruments and for use in home studios. It is not the best choice for subjects at a considerable distance.
Mid-Side Stereo Technique
The M/S stereo method is a flexible recording process that allows you to alter the result significantly.
In this method, you use one Cardioid mic and one bidirectional figure 8 patterned mic. One captures the mid-channel while the other captures the side channel.
In this technique, the cardioid faces forward, while the directional mic faces sideward. You will need to decode the recording later.
To do that, you can either use a software program or a manual audio editor.
It provides sound with variable width. You can raise or lower the gains of the side to create a broader or narrower stereophonic image.
It creates a stable middle image and places other sounds well within the range of the image.
It is a method that’s very popular for the flexibility it brings, which is why it is considered a safe recording method.
You can use it to avoid phase problems. It is ideal for capturing specific sound effects and ambiances while also providing a detailed soundstage.
A significant disadvantage of the technique is that it requires constant monitoring throughout the recording, which can be tricky.
Decoding also requires substantial knowledge that not everyone has.
ORTF Stereo Technique
The ORTF recording method utilizes two directional microphones.
In this method, the capsules are spaced around 17 cm apart and positioned outward.
Also known as the Side-other-Side technique, the angle between the two microphones is about 110 degrees.
Here, the two mics are positioned in a near-coincidental placement, which mimics the way humans hear.
It will give you a full stereo image and is perfect for outdoor recording sessions where you have a lot of movement to capture.
Because of the wider angle, you will have a broader pickup pattern, allowing you to capture multiple sounds at once.
The stereo image will be much more comprehensive.
With broader coverage, it also provides the possibility of introducing a baffle.
By incorporating one, you can further isolate the two microphones and mimic the shadowing effecting of the human head.
ORTF also has pretty decent mono coverage, especially when compared to the A/B recording technique.
It is easier to set up and can easily replace the Blumlein Stereo pair where necessary.
However, when switching to mono, the recording may suffer from phase cancellation. If mono is a requirement, then we suggest you do a trial run before you begin the production.
Another significant disadvantage of the technique is that the sound source at the center of the placement will not get enough coverage.
Because of the setup’s limiting frequency response, it will be off-axis from both microphones.
Blumlein Pair Setup
While conceptually, the Blumlein pair is simple, it is quite tricky to set up.
In this technique, you will use two bi-directional microphones placed as close together as possible. They will be placed at around a 90-degree angle to each other.
You cannot just use any mic in this method and will specifically require bi-directional ones with a figure 8 pickup pattern.
These provide equal coverage from front and back. It is essential that you use two of the same type, make, and model of microphones to avoid any discrepancies.
This is a coincidental setup in which one mic is placed over the other at a 90-degree angle. One of them will be panned hard left while the other will be hard right.
Each will primarily focus on sounds as per their panning, but will also simultaneously capture background noise.
The Blumlein pair setup provides a stable and articulate stereophonic image.
It creates a broad stereo field while also holding on to a significant chunk of the character in the room.
It provides a broader image with an excellent mono center, which is ideal for studio recording.
This setup will pick up even the most isolated stereo field. If you’re a musician and would like to cover all frequencies and reverbs when playing the drums or piano, this is the method for you.
It is a reasonably specialized technique that is not as easy to set up as others are.
You will need to invest a significant amount of time before you can figure out the ideal placement.
The characteristics of this method make it ideal for room coverage and less so for close-range acoustic recordings.
Typically, you will need to place your microphone set up as high above the source of noise as possible.
What is the Best Studio Recording Method?
When deciding which method is best, you need to keep these five factors in mind:
- Mono compatibility
- Ease of use
- Required sound
The subject is particularly important and will heavily influence your choice of the recording setup.
You need to consider the nature of the sound you’re capturing, your desired result, the breadth of the recording as well, as the distance to the subject.
For close subject recordings like sound effects, the X/Y setup is the best, whereas the A/B setup is better suited for capturing ambient sounds.
If you are looking for high mono compatibility, then you need methods that eliminate phase.
For such situations, ORTF works best, providing good mono coverage while being easy to use as well.
Many of these methods are not meant for mobile usage. To capture nature at its best, we suggest you use either the ORTF or X/Y set up.
Avoid the M/S method as neither is it easy to set up nor is it meant for mobility.
There are numerous other studio recording methods you can use, and your desired result mostly dictates the method you opt for.
Your decision will be based on whether you need a tightly focused recording sound or a spacious, atmospheric filler sound.