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Audio

The President's Microphone

ImageAmerican Presidents come and go but one constant since the administration of Lyndon B. Johnson has been the Shure Presidential microphone. Next time you see President Obama on television take notice. He almost always speaks into a pair of Shure SM57 dynamic cardioids – classic workhorses since the early 1960s now found in every conceivable sound reinforcement and recording application.

Why, with all the recent advances in microphone technology, does the White House still stick with the venerable SM57s priced at under $100?  The answer – from Shure's Michael Pettersen – offers a good primer for those who produce location sound.  A few years ago, Pettersen prepared the following memo for the technicians who provide sound services for the President.  He edited a special version for us:

Assumption: The President will speak in a variety of situations, both indoors and outdoors.  Weather conditions will vary from very cold to very hot; very dry to very humid; no wind to high wind. Failure of the microphone in any of these situations is unacceptable. In addition, the microphone must endure physical abuse as it is packed and shipped throughout the world.

It is the strong recommendation of Shure's Engineering staff that a dynamic microphone be used when absolute reliability is demanded. While condenser microphones are a valuable tool and reliable in controlled, benign environments, condenser microphones are not recommended for critical applications where environmental conditions are uncontrolled.

ImageHere are our reasons. (Shure manufactures condenser and dynamic mics, so our experience is extensive with both.)

1. Mean Time Between Failures:  Condenser mics are inherently less reliable because they have many more individual components than dynamics.  Every condenser mic has an associated preamplifier which is made up of individual electronic components, all of which have their own rate of failure. Any one of these can cause a condenser mic to fail.  The more parts, the more failure possibilities.

2. Humidity and High Temperatures:  The combination of these two conditions can cause unwanted noise (hissing, popping, crackling); or change the actual sound of the microphone (frequency response shifts, changes in transient response); or even complete failure. Any of these are likely with humidity levels of 95 percent and temperatures around 100 degrees F.  Remember, these conditions can easily happen in shipping and storage.

3. Wind Noise: The mass of a condenser diaphragm (the part that moves when the President speaks) is much less than a dynamic diaphragm. Since it is lighter, it will be much more susceptible to wind noise.  Therefore, a large windscreen will be necessary to cut down the wind noise. We predict it would have to be as big, if not bigger, than the A81SW (windscreen) you use now for the SM57. Also, condensers are much more likely to pop from P-words or large exhalations of breath.

4. Long Term Performance: It is well documented that the performance characteristics of condenser mics can often change substantially over time.  This will make it imperative that you use mics together that are about the same age.  New ones could sound much brighter than older ones. We imagine that would be a difficult task based on your large inventory of products. Dynamic mics are very stable as they age and tend to sound the same until they are retired.

Image5. Phantom Power: To operate, condenser mics need DC phantom power applied through the mic cables.  (We doubt you would even consider battery powered condenser mics!)  It is unlikely that the phantom power provided by your Shure mixer would fail, but it could be switched off accidentally. More likely is noise (cracking, popping) caused by bad cables or loose/dirty connectors.  This type of noise can appear when phantom power is used.  But the same cable and connectors can be perfectly quiet when used with a dynamic mic, as there is no DC phantom power flowing in the cable.

Though much has changed in microphone technology over the years, we still hear the President's voice through the SM57. Sometimes there's good reason to stay basic with the tried and true. Food for thought next time you see those battle-scared SM57s on the President's lectern.

The Shure SM57 is priced at under $100.  Shure also sells windscreens and dual stand mounts in a "VIP Kit" like those used by the President.  For information: www.shure.com.