Study Hall
Sponsored by
Audio Technica

Successful Capture: Advice About Microphones In The Live Recording Quest

Extending the discussion about the "right" mic for recording the live stage and examining the various strengths of each type.

By Craig Leerman January 10, 2018

A DPA d:dicate 2011C twin diaphragm cardioid microphone on acoustic guitar.

Early in my career, I heard there were two types of microphones: “live” models rugged enough to be used on stage and “studio” models that were only used for recording because they were fragile. As I learned more about our craft, I understood that this was a misnomer, as any microphone could be used any place, and while some were indeed more fragile than others, these could still be deployed on a stage where appropriate.

I think what kept live technicians away from “studio” mics was the fact that many models have omni or figure-8 pickup patterns that aren’t ideal in most live situations. That and the higher cost, especially vintage favorites like the Neumann U87 where the price of a clean used model is equal to the cost of a stage full of dynamics for a small band. We all know that the average live audio tech is not rolling in dough (though they may be rolling dough at a pizza place as a side job to help pay the bills).

Now that I’m a well-seasoned (from making pizza and breadsticks) technician, I clearly see the differences between mic types and understand how best to use different models to my advantage. Where it can get interesting is making mic choices when recording live events.

There’s a saying that great recordings start at the source, and that involves the “right” mic. I’ve covered the “right” topic previously as it pertains to the live performance, but here I’m going to extend the discussion to focus on the recording aspect as well. First, let’s first take a look at what types of microphones are available and examine their various strengths.

Operating Principles

Dynamic mics have a voice coil attached to the diaphragm, and as the sound waves strike the diaphragm, it moves the coil inside a magnet creating an electrical signal, like a loudspeaker in reverse. Dynamics are usually rugged and many are designed to handle high SPL (sound pressure levels), so they work well on loud instruments and amplifiers as well as singers.

Shotguns can play a key role in the live recording process.

They’re the most popular choice in the live sound world due to that aforementioned ruggedness in addition to being relatively inexpensive and not requiring a power supply. Be advised that some models have factory-tailored frequency responses designed for certain instruments and may not work well with every instrument.

Condenser mics use two plates with a voltage between them. One of the plates is made of very light material and acts as the diaphragm. The diaphragm moves when struck by sound waves, changing the distance between the two plates and therefore changes the capacitance. For this to work, a voltage needs to be applied to the circuit from a battery or more normally from phantom power provided by the console.

Condensers usually offer good sensitivity at all frequencies, and because the diaphragm is not weighed down with a coil like a dynamic, they’re quite adept at capturing soft and high-frequency sounds, as well as fast transients, but may suffer from lesser performance in high humidity.

Ribbon mics have a thin, corrugated strip of conductive ribbon (typically aluminum) suspended between two poles of a strong magnet as the diaphragm. The element responds to sound from both front and back of the ribbon but is insensitive to sounds coming from the sides, so most models have a natural bi-directional pattern (more on patterns in a bit). They sound natural, don’t need phantom power and work by picking up the changes in air velocity, but excessive air pressure from high wind or very loud SPL can damage ribbon mics.

Some mics use two or more different types of diaphragms in the same housing with different outputs, giving the mix engineer a choice between the types or a blend of the two. A recording colleague likes to use these whenever possible because it provides a choice of one mic for the PA and the other for the recording from only a single housing on a single stand. He admitted to me he chooses the better sounding element for the recording and leaves the other element (which stills sounds good) for the live system.

Mic diaphragms come in a lot of different sizes that we typically classify into four basic groups: “mini” (i.e., lavaliers and headworns), “small” (i.e., pencil condensers), “medium” (i.e., some vocal, guitar and drum models, and “large” (i.e., kick drum mics and big studio models). A popular myth is that a large diaphragm is needed to pick up low-frequency sounds, but in reality, many smaller diaphragm models, as well as ribbons, do well with bass frequencies.

Pattern Options

There’s an area around the front of each mic where sound is best captured called the pickup pattern (a.k.a., polar pattern because the shape is often plotted on a polar graph to show where the mic is most and least sensitive).

Mics are available with different pickup patterns to suit various requirements. An omnidirectional pattern picks up sound equally well all around it, helpful in the recording studio but not so great on stage where other instruments will “bleed” into them. A subcardioid pattern provides directionality and is more sensitive to the front and sides than the rear.

Selection of microphone polar patterns. (Credit: Shure)

 

A cardioid pattern picks up sound better in the front and rejects it from the sides and rear. Super- and hypercardioid patterns are much more directional than cardioid, but they have a lobe of sensitivity behind the mic so careful placement is required. Shotgun designs have an extremely narrow pickup pattern at the front and are good at isolating sounds from the sides, with a narrow lobe at the rear. A figure 8 pattern (which looks like the number “8”) picks up sound equally well at front or back, with null zones at the sides.

As mentioned, some models are designed manufacturers to have a tailored frequency response for a particular application. They may also include frequency roll-off or high-pass switches for optimization for certain applications.

Don’t assume that just because a mic looks similar to a model you’re familiar with that it will work the same. It’s important to know the pickup pattern and frequency response in order to choose the best one available for each application. How a mic converts sound waves to electrical energy is not as important as where it picks up sounds and what frequencies it can reproduce well.

Here are primary issues to keep in mind. Many “studio” models tend to have larger diaphragms, may have fragile tubes in their circuits, may need external shock mounts to eliminate transmission of floor noise via the stand to the capsule, and have omni and bi-directional pickup patterns that aren’t ideal for a stage. “Live” models tend to have medium to small diaphragms, which makes them more compact, and many are optimized for handheld use with built-in capsule isolation and/or compact shock mounts.


Read the rest of this post

1
2


About Craig

Craig Leerman
Craig Leerman

Senior Contributing Editor, ProSoundWeb & Live Sound International
 
Craig has worked in a wide range of roles in professional audio for more than 30 years in a dynamic career that encompasses touring, theater, live televised broadcast events and even concerts at the White House. Currently he owns and operates Tech Works, a regional production company that focuses on corporate events based in Reno.
http://www.techworksvegas.com

Tagged with:

Subscribe to Live Sound International

Subscribe to Live Sound International magazine. Stay up-to-date, get the latest pro audio news, products and resources each month with Live Sound.

Latest in Live Sound