Recording & Production Articles

Understanding Microphones - Dynamics vs. Condensers

Every microphone is different and imparts its own unique sound to whatever you are recording.  There is a very good reason why the best studios have a very large assortment of microphones.... you simply need lots of different types of microphones to be able to get the sound you are looking for.  After working with lots of microphones for a while, you'll quickly learn the sound characteristics of each and will be able to more accurately choose the right microphone for the job the next time you are recording something.

The difference between dynamics and condensers really comes down to the physics of their operation.  Without getting into all the boring physics, A dynamic microphone has a diaphragm that is directly connected to a core of wire called the "voice coil" that is suspended in a magnetic field.  The movement of the diaphragm causes the voice coil to move in the magnetic field and thus creates an electrical signal that's proportional to the acoustical pressure waves from the source that you are recording.  Condenser microphones use electrostatic properties, and consists of two thin plates, one moveable and one fixed, that form a capacitor.  As the moveable plate moves in relation to the acoustical pressure waves, the capacitance is changed between the plates, and the voltage across the plates will change in proportion.

What does all this mean in practical applications?  In general, dynamic microphones have diaphragms of larger mass that take more energy to move, and that don't respond quite as quickly as the lower mass diaphragms in condenser microphones.  Thus, there are certain sound characteristics that each design typically shows.  Dynamics can usually handle much sound pressure level than condensers (although today's condensers can handle much more) and usually work better for percussive sources (close mic'ing drum kits) or really loud sources (close mic'ing guitar cabinets).  They also work well in live sound situations because they don't tend to cause feedback problems as much as condensers do (although a lot of this has to do with the pickup patterns used and the placement of the mics and the room acoustics).  They are a lot more durable and can handle a lot more abuse than a condenser microphone as well.  Since condenser microphones have much lighter diaphragms, they typicall react much quicker to incoming signals, and thus they usually have a much more open and detailed high frequency response than a dynamic microphone.... since they can react to the high frequency transients much quicker.  This is why condensers are usually preferred for sources where you want more of that brighter, yet clear and detailed high frequency sound, such as vocals, acoustic guitars, piano, drum overheads or room mics, etc.  Within the condenser category, there are large diaphragm condensers and small diaphragm condenser microphones.  As you might expect, the smaller diaphragm condensers can react even quicker and often have even better high frequency response, but at the sacrifice of the low end warmth... the smaller condensers are usually used for acoustic guitars and overheads/cymbals for drums, because you usually want a lot of high-end detail with very quick transient response for these types of sources, and you don't care as much about the low end.  Large diaphragm condensers are usually associated with being warmer and bigger sounding, and thus are quite popular for vocals or solo instrument work.

Those are very generalized descriptions.  There is quite a lot of variety in each type of microphone, because there is a lot that can be done to change a microphone's sound in the design stage.  Some microphones are designed to be very flat and neutral sounding, while others are designed to really emphasize certain frequency ranges.  Also, understanding the types of pickup patterns is very crucial as well.... These are omni-directional, bi-directional (figure 8), cardioid, super-cardioid, and hyper-cardiod (and then some special ones that I won't get into).  Basically, you just need to know that some microphones are omni-directional, meaning that they pick up sound equally well from all directions, while others are directional ... meaning that they pick up the most sound from directly in front of the diaphragm, and reject the most sound from directly behind (most stage microphones are directional so that they will reject the greatest amount of sound from directly behind them where the floor monitors are usually placed, to avoid feedback as much as possible).  One of the things to keep in mind when using any type of cardioid pickup pattern microphone is what is called the "proximity effect".  When you get within about 6 inches of a directional microphone, you get a sort of bass boost type of effect due to the close proximity.  This is something to keep in mind when tracking vocals in particular... sometimes this effect is desirable for certain vocalists, but not desirable for others.  Also, many high end microphones have more than one diaphragm and will allow you to change the pickup patterns of the microphone between various directional and non-directional settings.  This can really change the sound of the microphone and make it much more useful in a wider variety of situations.

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