Getting ORTF drum overheads right is often the difference between a drum recording that sits firmly in the center of a mix and one that translates poorly across different playback systems. This specific stereo technique, named after the Office de Radiodiffusion Télévision Française, uses a spaced pair of cardioid microphones positioned just above the drummer’s head. The goal is to capture a realistic stereo image while maintaining strong mono compatibility, a balance that makes the ORTF method a staple in both live and studio environments.
The Core Principles of ORTF Placement
The foundation of any successful ORTF drum overhead setup lies in the precise geometry of the microphones. Two identical cardioid capsules are mounted roughly 17 centimeters apart, pointing downwards at an angle of approximately 110 degrees relative to each other. This specific arrangement creates a 96-degree angle between the capsules’ axes, which is the key to its signature sound. The spacing mimics the distance between human ears, while the angle helps to minimize phase cancellation without sacrificing a wide, natural stereo field.
Microphone Selection and Pattern
While the technique can be applied with various microphones, choosing the right pair is critical. Small-diaphragm condenser microphones are the most common choice due to their ability to capture high-frequency detail and transient response without introducing coloration. It is essential that both microphones are identical; any deviation in frequency response or timing will skew the stereo image. The cardioid polar pattern is non-negotiable, as it provides the necessary rear rejection to isolate the kit from spill from other instruments, such as amplifiers or vocal microphones.
Practical Setup for Overhead Microphones
Positioning the microphones correctly requires a bit of trial and error, but there are reliable starting points. The ideal height is just above the drummer’s head, ensuring the capsules are looking down on the snare drum and toms. The stereo axis should align with the center of the snare drum. To adjust the width, move the pair closer together for a tighter image or farther apart for a wider one, but avoid exceeding the 17-centimeter standard unless you are aiming for a more extreme effect. Keeping the capsules at the same height as the cymbals ensures that the snare and hi-hat sit prominently in the stereo field.
Addressing Phase and Mono Compatibility
One of the primary challenges with spaced pairs like ORTF is phase correlation. If the microphones are too far apart relative to the sound source, the left and right channels can develop timing differences that cause phase cancellation, particularly in the lower midrange. To check mono compatibility, sum the stereo signal to mono early in the recording chain. Listen for elements that thin out or disappear; the kick and snare should remain solid and centered. If issues arise, try narrowing the mic spread slightly or lifting the microphones higher to reduce the angle of incidence from off-axis sound sources.
Capturing the Drum Kit in Context
Unlike close-miking techniques that isolate specific drums, ORTF overheads capture the entire kit as a cohesive unit. This provides a natural sense of room and depth that is difficult to achieve with processing alone. The technique excels at preserving the transient punch of the snare and the shimmer of the cymbals, resulting in a sound that feels alive and dynamic. When used as the primary stereo pair, the overheads establish the foundational width, allowing engineers to subtly blend in close mics for impact and clarity.
Integration with Close Miking
In a full drum recording scenario, ORTF overheads function best when combined with individual close-miked elements. The overheads should sit slightly back in the mix, acting as the glue that holds the kit together. Blend them with microphones on the snare, kick, and toms to create a three-dimensional soundstage. The overheads provide the "3D" perspective, making the kit feel like it is floating in front of the listener. This synergy between close and ambient miking is where the ORTF technique truly shines, offering both impact and naturalness.
