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What is the difference between dynamic and condenser microphones?

Discussion in 'Microphones' started by audiokid, Jul 2, 2010.

  1. audiokid

    audiokid Staff

    The terms dynamic and condenser refer to the two most common forms of professional microphones. Could someone explain this for our readers?
     
  2. Boswell

    Boswell Moderator Distinguished Member

    The term "dynamic" refers to any microphone where the source of energy for creating an electrical signal is the sound wave itself. This category includes moving-coil, ribbon and moving-plate designs (used in espionage!). A dynamic microphone is inherently low impedance and so does not usually have a buffer between the electrical element and the cable, but there is often a step-up transformer to increase the output amplitude at the expense of a higher output impedance.

    The term "condenser" is colloquially used to refer to what should properly be called "capacitor" microphones. In these, the sound waves moves a diaphragm, but it is the changing capacitance between this moving diaphragm and a fixed plate that is used to convert to an electrical signal. The charge Q held on a capacitor of value C is given by Q = C * V, where V is the voltage across the plates, so for a constant stored charge, the voltage varies with the inverse of the capacitance and hence with the incident sound waves. Since the impedance of this arrangement is very high, a microphone operating on this principle needs a buffer amplifier or voltage-follower located within the body of the microphone in order to drive the relatively low impedance of the cable and pre-amplifier input.
     
  3. lbeasley

    lbeasley Active Member

    I covered this in a quick and simple video series several weeks ago. I touched on the most basic differences. Hopefully this will be of help to you or anyone else.

     
  4. producerspot

    producerspot Active Member

    Depending on what you need to record. For example for recording voicals, or acoustic instrument, the best way is to use a condenser microphone. Most condenser microphones have the ability to set multiple polar patterns: cardioid, omnidirectional, bidirectional, directional, etc..
     
  5. paulears

    paulears Well-Known Member

    The important thing is to make sure you understand that sound hitting a microphone has very little power, so in a dynamic it needs to be strong enough to move a diaphragm in a coil enough to produce electricity. In a condenser (and blame the Brits for the name - we always called capacitors condensers in the good old days - and tubes were to us, valves) the diaphragm can be very thin and very light, so it can respond better to weak sounds - the amplifier inside looking after the conversion into electrical energy.

    The practical upshot of this is that dynamic mics work well on loud sounds, and are pretty tough mechanically - and don't need power to work. Condensers are best for highly detailed sound and quieter sound sources - but can be delicate and expensive. Expensive condenser mic on a snare drum? Nice bright sound, until the drummer hits it. ice cream cone shaped mic on a flute from 6 feet away might mean turning the gain right up - so a noisy end result.
     
  6. DonnyThompson

    DonnyThompson Distinguished Member

    Not always on either count. It depends greatly on the environment, the vocalist...and the mic.

    If I have a choice between a low budget Chinese condenser and a nice dynamic like an SM7 or an RE20, I'm gonna reach for the dynamic... every time.

    And, there are many models of condenser mics, from budget to boutique, that don't have multiple pattern choices, that are simply cardioid. Even Neumann has models where cardioid is the only pattern.
     
  7. John Willett

    John Willett Active Member

    Actually, most condenser microphones do *not* have the ability to switch polar-patterns.

    Many large diaphragm condensers do, though many do not.
    Most small diaphragm condensers are fixed pattern, though there are a few which can be changed.

    Also, a condenser mic. has a very light and responsive diaphragm which can more closely follow the waveform than the comparitively heavy diaphragm of a moving coil microphone.
     
  8. Shawn Newman

    Shawn Newman Active Member

    that video is a pretty good primer, lbeasley
     

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