When recording a band live in the studio, paying attention to microphone pickup patterns during setup can help minimize bleed. Also known as “spill” or “leakage,” bleed occurs when mics pick up audio from sources other than what they were intended to capture. In this excerpt from History of the Beatles Recording Techniques: Episode 4, we see Ken Scott setting up the vocal mic, a Neumann U47, similar to how it was done in an early Beatles recording session.
By choosing a mic with a figure-8 (aka “bi-directional”) polar pattern and placing it strategically, Ken makes it possible for two vocalists to sing into it while keeping bleed from the other instruments to a minimum.
Right Angles
For those unfamiliar, a figure-8 mic picks up equally from the front and back of the capsule but rejects sound coming from the sides. It was a “no brainer” for Ken to choose a mic with such a pattern for the vocals, considering there were two singers on one mic and guitar and bass amps and a drum kit in the room. It also didn’t hurt that the U47, a tube condenser, is considered among the top vocal mics of all time.
Ken positioned the singers, bassist Tony Skeggs and guitarist Jimmy Vivino, facing each other at the front and back of the mic, with one of the null sides pointed at the drum kit and guitar amp.
Notice how the sides of the mic are pointed at the drums and guitar cabinet.
Here’s an excerpt from the raw vocal track soloed in the control room. (A little compression was added strictly for this example.)
As you just heard, there’s surprisingly little bleed picked up even though all the instruments are in the same room as the vocal mic. The drums leaked through more than the bass or guitar. Still, considering the situation, using the figure-8 pattern helped reduce bleed significantly.
Other Possibilities
Had there been only one vocalist, it would have made sense to place the vocalist in front of a cardioid-pattern mic, facing opposite the drums. Doing so would minimize bleed into the vocal mic and thus onto the vocal track.
This shows the pickup pattern of a cardioid mic and the best placement with one vocalist. (Cardioid pattern diagram by Nicoguaro, CC BY 4.0).
Mics with hypercardioid or supercardioid patterns are even more directional than those with a cardioid pattern. If you need more rejection of sounds from the sides than you’re getting from a cardioid micyou might try one, particularly supercardioid. However, they both pick up more in the back than regular cardioids.
Hypercardioid (left) and supercardioid (right) are more directional in front than cardioid, but pick up more at the back. (Diagrams by Galak76)
If you’re recording group vocals, you could fit at least two singers on each side of the figure-8 mic while still positioning it for minimum bleed. Even though an omnidirectional mic is sometimes used in a group vocal situation, it would be the wrong choice for a “live in the studio” recording because it picks up equally all around, and thus would get a lot of bleed from the instruments.
The polar pattern for an omnidirectional mic. (Diagram by Galak76)
That said, if you’re overdubbing a vocal group with four or more singers, an omni mic can be beneficial because you can position them all around the mic. Bleed won’t be an issue during overdubs. You’ll have to experiment with how close to the mic each singer stands to make sure the blend is good. Naturally, if everyone is recorded on a single mic, the result will be a mono track.
Proximate to What?
Another characteristic of an omni mic is that it exhibits no proximity effect (additional low end as you get closer to it). Conversely, a figure-8 mic creates the most pronounced proximity effect of all the polar patterns. For vocals, that’s often a good thing because it makes the singer’s voice sound bigger. Cardioid mics also have a fairly pronounced proximity effect.
Whether or not you want the proximity effect depends on the sound you’re going for. It should be among the factors you consider when choosing a vocal mic for recording more than one singer at a time.
Here are examples demonstrating the proximity effect with different patterns. These spoken word examples were all recorded with a Mojave Audio MA-300 multipattern tube condenser.
In the first example, we compare the different patterns with the speaker three inches back from the mic.
Next, the speaker is one inch back from the mic.
This gives a better sense of the proximity effect differences between patterns. One disadvantage of being so close up on the mic, particularly with cardioid and figure-8, is that the proximity effect accentuates plosives (popped P, B and other consonant sounds). Using a pop screen when singing or speaking close to the mic is essential.
While it’s true that you probably use cardioid mics most of the time, there are situations (such as the session in the video) where knowledge of the characteristics of the various pick patterns can dictate your vocal mic choice.