An Introduction to DIS
Webinar Description
DIS Discussion & Conference Systems offer a compelling alternative to traditional PA-based speech reinforcement systems. By providing users with localized sound reinforcement via small speakers integrated into the microphone units or through headphones, DIS systems make setup much easier. Simple connectivity and intuitive meeting control are but a few of the many benefits of both the DDS 5900 and DCS 6000 systems.

Join Technical and Education Communications Manager Chris Lyons and Product Marketing Manager Luis Guerra for a comprehensive look at the advantages of this style of conferencing and highlights of the features of the two DIS systems.

Dates & Times
Monday, March 4, 2013; 2:00 PM – 3:00 PM CDT Register for the 3/4 Webinar

Wednesday, March 6, 2013; 10:00 AM – 11:00 AM CDT Register for the 3/6 Webinar

Troubleshooting Wireless Microphone Systems
Webinar Description
“My wireless microphone is dropping out. What should I do?” If you’ve ever asked yourself this question, or been asked to help someone else answer it, this webinar is for you. The vast majority of wireless microphone problems can be solved by following a few simple, but often overlooked, steps.

Join Shure Systems Support Engineer Tim Vear for step-by-step instructions for identifying the likely causes of dropouts, noise, or reduced operating range, as well as practical tips for maximizing the performance of your systems. Come prepared with questions!

Dates & Times
Monday, March 18, 2013; 2:00 PM – 3:00 PM CDT Register for the 3/18 Webinar

Wednesday, March 20, 2013; 10:00 AM – 11:00 AM CDT Register for the 3/20 Webinar

After you register, you’ll get a confirmation email that’ll tell you how to join the webinar.

System requirements for PC-based attendees: Windows® 7, Vista, XP, or 2003 Server. For Macintosh®-based attendees: Mac OS® X 10.5 or newer required.

Happy learning!

View archives of our webinars at your convenience on shure.com.

Tim Vear, also a guitar wizard, before Shure’s Annual Holiday Show in 2012.

One of the ways that we zero in on what you want from us is to check in with Senior Applications Engineer and Shure Answer Man Tim Vear.

Not only is he a featured speaker at countless workshops and seminars, he wrote the book on Audio Systems for Houses of Worship which many of you probably have in print or digital form.    This booklet is constantly in update mode, explaining its fifteen versions.  So far.

Tim, who can describe the physical characteristics of wavelengths and make it both understandable and interesting, was the lucky fellow we tapped just a few days before Christmas to share some of your most recent church audio-related questions and concerns.

Here are the top six, not only from his phone, email and online encounters with you at Shure headquarters, but from his recent audio seminars at Worship Arts Technology Summit and other events.

How do I mic the congregation (for recording or broadcast)?

Generally, it’s desirable to have some direct pickup of the congregation to add ambience and energy to a recording or broadcast of your service.

The usual technique is to treat the congregation as a very large choir: place one (or two for stereo) microphone(s) above and somewhat in front of the congregation.

Just as for choir applications, a flat-response, cardioid condenser microphone is recommended. Aim the microphones at the faces of the people and away from the main PA speakers as much as possible.  This will insure that the resulting sound is mostly from the audience and not from the PA.

During a broadcast, the sound from these microphones can be brought into the overall mix at the desired level, typically lower when the pastor or worship leader is speaking and higher for musical sections, particularly when the congregation is singing.  For recording, it’s sometimes useful to record the congregation mic(s) on separate track(s) for sweetening of the final mix.  Note that the congregation mics should NEVER be routed to the main PA mix.

One example of miking the congregation in an auditorium setting to add a pinch of spice to the recording or broadcast mix.

How can I pick up individual congregation members who need to speak?  

If you’re trying to pick up the sound from an individual congregant, it may be possible to use the technique above – but ONLY for recording or broadcast.  Since the congregation mics will usually be at some distance from any individual talker, the engineer will have to bring up the level of the nearest mic to pick up that source. Even then, the sound quality from the distant microphone is likely to be poor.

A better technique is to bring a microphone (usually wireless) close the individual. This requires a microphone “wrangler” (and sometimes multiple microphones) to get the mic into position quickly.  Just as for other close-up vocal applications, a shaped-response, cardioid microphone is recommended.  If you plan to amplify the congregant in the main PA, then ONLY the close mic technique will work.  A distant microphone (greater than a couple of feet away) cannot achieve usable gain-before-feedback when it’s amplified through the main PA system.

Headset mics like the Countryman WCE6 place the mic within
inches of the speaker’s mouth

Why doesn’t the pulpit microphone sound the same as a lapel or headset microphone?

The reason that these microphones have different sound qualities is almost completely dependent on the distance from the microphone to the mouth of the talker.  The closer the microphone, the better the signal-to-noise ratio, the better the gain-before feedback, and the better the low-frequency response (for directional microphones).

The signal-to-noise is improved because the level of the voice increases by 6dB each time the mic-to-mouth distance is cut in half while the background noise stays constant.  The gain-before-feedback is improved in a similar manner, resulting in either higher level with the same feedback potential or the same level with lower feedback potential.  The low-frequency response is improved because the closer placement increases proximity effect for a directional microphone.  Overall, a close microphone placement will give significantly better performance, particularly in live-sound applications.

Is it safe to use a wireless microphone in a baptistry?

Sometimes there’s a need to use a microphone in a “wet” environment such as a full-immersion baptistry.  Although a properly grounded sound system and baptistry installation should be safe even for use with a wired microphone, a wireless microphone eliminates any possibility of a ground-fault that might be hazardous to the wearer.

The only suggestion would be to protect the microphone and/or transmitter electronics from direct contact with water as much as possible.  Such contact is not dangerous, but the microphone (particularly a condenser type) and/or the transmitter may stop working if water intrudes into the mic element or the electronics.  There are waterproof pouches and even waterproof microphones that can be used in this case.

Can I use rechargeable batteries in my wireless systems?

Rechargeable batteries can be cost effective and environmentally friendly alternatives to single use devices.  The principle considerations are the operating voltage, the run-time, and ultimate lifetime capability of the rechargeable.  Here’s how the different types of rechargeable and non-rechargeable batteries compare. 

The table above gives typical capacities of popular 9V batteries.

The table above gives typical capacities of popular AA batteries.

These characteristics depend on the specific chemistry of the battery.  For transmitters that use AA batteries, both nickel-metal-hydride (Ni-MH) and nickel-cadmium (Ni-Cd) types may be suitable.  Though they have somewhat lower operating voltage than alkaline types (1.2 V vs. 1.5 V) their run-times are fairly similar.  However, for 9-volt size applications, the run-times are much less than with the equivalent alkaline.  For this reason, we suggest using a Lithium-polymer (Li-Polymer) chemistry.  This battery has an operating voltage and run-time similar to an alkaline 9-volt type.  Note that the Li-polymer chemistry is not available in AA size cells.  Any of these batteries should be used only with their specific chargers and operated with regard to manufacturers suggestions in order to get the maximum life.

A properly maintained rechargeable should be capable of up to 500 charge/use cycles.

Are directional antennas always the best choice for my receivers?

Shure UA874 directional antenna – antennae like these can be stand-mounted, wall-mounted or suspended.

Directional antennas are usually recommended for specific applications only.  These include operation over long transmission distances (greater than 150 feet) and/or operation in the presence of localized interference sources.

Directional antennas typically exhibit increased sensitivity in one direction and less sensitivity in other directions.  The most common directional antenna is the log-periodic type, often called a “paddle” antenna because of its shape.  In the direction of increased sensitivity, the antenna can deliver a stronger signal to the receiver, which can increase the effective range of the system.  At the same time, the antenna can offer some rejection of interfering signals coming from other directions.

However, most directional antennas are wideband devices.  They are equally sensitive to all frequencies in their operating band.  This means that a directional antenna aimed at an interfering source will increase the level of that interference as well as whatever desired signal may be in that same direction.  Finally, too much antenna sensitivity (gain) may result in overload of the connected receivers.  This can aggravate intermodulation and actually desensitize the receiver.  For most applications omnidirectional antennas are still the norm.

Download the current edition of Audio Systems Guide for Houses of Worship right here.

Readers of Shure Notes have enthusiastically embraced our annual review of audio myths, which Tim Vear shatters (or not). Here he delivers the answers to some of the most recent questions that originate from Shure customers who call Tim and his fellow Apps Experts for help.

Myth: Loud sounds can blow out a microphone

False.

Generally it is not at all likely that a loud sound will damage a microphone.  A dynamic microphone can handle levels above 150dB SPL. That’s not a volume that can be achieved short of shoving a microphone into the exhaust of a jet engine.  It is almost impossible to physically damage a dynamic microphone at any achievable sound level.

Classical ribbon microphones that use an aluminum ribbon can be damaged not by sound pressure but by a puff of air.  A blast of air could physically push the ribbon out of its magnetic gap far enough to stretch it. (It’s worth noting that Shure’s ribbon mics use a material – Roswellite^® - that can withstand air pressure making them about as durable as any other Shure microphone.)

Condenser microphones can experience distortion if the sound pressure level exceeds the rated capability of the mic.  But the distortion is coming from the electronics of the microphone and not the capsule itself. The electronics are essentially a fixed gain amplifier. Any amplifier has a maximum output level that it can deliver before it distorts.  So if you increase the input level to the amplifier beyond what the max should be, it will drive the amplifier to distortion.  It’s the pre-amp in the condenser microphone that’s distorting.

Many condenser mics feature a switchable attenuator that allows the mic to handle higher sound levels.

Myth: A wireless microphone can’t cause feedback.

False.

We get this question every once in a while from someone who may be using a wireless mic either for the first time or in a new way.  They’re surprised to experience feedback when using a wireless mic in front of loudspeakers.

They believe that if they eliminate the wire, they’re eliminating the feedback loop.  The fact is, the cable is just being replaced by a radio wave, so acoustically; the system behaves exactly like a wired system.

It may be triggered by someone who is accustomed to using a wired mic that’s tethered to a mic stand or pulpit.   A wireless mic gives the user the ability to walk around in the audience or among the congregants and potentially in front of the house speakers. In that case, the system may very well cause feedback.

If the user is too close to the speakers or the gain is turned up too high, feedback will occur in both wired and wireless systems.

Myth: Digital wireless microphone systems are interference free.

False.

Some people believe that the error correction capabilities of digital systems can compensate for extreme radio interference.  But the fact is that any radio microphone or wireless device can experience interference because there is no frequency band that is reserved specifically for an individual’s wireless microphone.   At minimum, there are other wireless microphones operating in the same frequency range and if they happen to collide, interference will occur.

Each frequency band has its own unique interference sources – it could be television stations in the UHF band or baby monitors in the 900 MHz band, WiFi hotspots in the 2.4 GHz band – but all frequency ranges are shared by different users that can interfere with one another.

Whether the transmission is digital, analog or some unknown modulation that hasn’t been discovered yet, if it depends on a radio signal, it is subject to interference.

Myth: It’s OK to use just one earphone for in-ear monitoring.

False.

There’s a functional reason and there’s a health reason.

Functional: With only one earphone in place, you have only the possibility of monophonic sound.  Whatever the mix is that you’re listening to; you’ll only hear it in mono, which removes all of the spatial cues that you get from a stereo mix.  A stereo mix makes it not only more pleasant to listen, but also enables you to pick out the parts that you need more easily by virtue of their pan location, not just their level.

Health:  If both ears are exposed to an open sound field, the perceived level of sound at each ear will be equal.  However, if one ear is blocked from the outside sound but presented with that same sound via an earphone while the other ear is still exposed to the open sound, the relative level perception changes.  It is found that in order for the sound levels to appear equal, the level of the earphone sound must be about 6dB louder than the level of sound at the open ear.   This is called the “occluded ear effect.”

Here’s an example: Let’s say the left ear is being exposed directly to ambient sound and the listener wants to match the sound level that’s coming through the earphone in the right ear (the occluded ear) so that the volume appears roughly equal.  By measuring sound levels at the eardrum, studies have shown that the listener will increase the earphone level at least 6dB above the open ear level to perceive an equal level. So in a loud environment where the open ear may be subject to 120dB SPL, the earphone may be cranked up to 126dB SPL just to compete. Over time, this increases the risk of noise-induced hearing loss.

It’s not a huge problem in a quiet environment – a jazz band or maybe a theatrical application – but for a heavy metal, rock and roll or even a loud country band – it’s a serious consideration.

Myth: Phantom voltage is the same thing as bias voltage.

False.

Phantom power is a dc voltage (11 – 48 volts) that powers the active circuitry of a condenser microphone. Phantom power is normally supplied by the microphone mixer, but may also be supplied by a separate phantom power supply. Phantom requires a balanced circuit in which XLR pins 2 and 3 carry the same dc voltage relative to pin 1. So if a mixer supplies 48 volts of phantom, XLR pins 2 and 3 of the microphone cable each carry 48 volts dc relative to pin 1. Of course, the mic cable carries the audio signal as well as the phantom voltage.

Bias is a dc voltage (1.5 – 9 volts typically) that is provided on a single conductor.  Unlike phantom power, bias does not require a balanced circuit. Bias supplies power to a single Junction Field Effect Transistor (JFET) connected to the output of an electret condenser mic element. The JFET acts as an impedance converter, which is a necessity in any microphone design that uses a condenser element. A condenser element has a high output impedance (>1,000,000 ohms).  The JFET lowers the output impedance of the condenser element to about 1000 ohms to feed the signal to the rest of the microphone active circuitry.  Typically, the JFET impedance converter is placed very close to the condenser element to prevent the loss of high frequencies that would occur from even a short length of high impedance circuitry.

How are phantom power and bias voltage related?  In a full-size condenser microphone, phantom power operates the active electronics in the body of the microphone – and those electronics have the function of converting the unbalanced signal from the condenser element to a balanced output signal. The electronics may also provide some equalization and possibly some amplification.  Finally, those same electronics provide the bias voltage that powers the JFET impedance converter connected to the actual condenser element.

Since the JFET impedance converter allows some length of connecting cable without high frequency loss, it is possible to separate the main condenser electronics from the actual microphone element.  This is the form used for condenser microphone designs in which the microphone element is connected to the main electronics assembly by a miniature cable up to perhaps 30 feet in length.  This cable conducts bias voltage from the main electronics to the JFET attached to the condenser mic element.

In some condenser microphones, the bias voltage must be supplied on the same conductor as the audio. Condenser elements with a built in JFET use this configuration and employ a single conductor, shielded cable. Other designs utilize separate conductors for bias and for audio. Consult the manufacturer’s data sheet to find out the exact wiring configuration for a specific microphone.

It’s important to understand the phantom vs. bias distinction when using wired microphones with a wireless transmitter.  A typical wireless bodypack transmitter provides bias voltage on its input connector. Any condenser microphone element with an integrated JFET can be plugged into such a transmitter.  This includes most condenser lapel mics, headset mics, as well as boundary mics and miniature gooseneck mics that have removable electronics assemblies:  these microphones only require bias voltage provided by the wireless transmitter.

But you cannot plug in a Beta 87 or a KSM32 or some other full size microphone that needs phantom power into a device that only provides bias voltage.  Those microphones can only be used with mixers or other devices that provide phantom power.

Here’s what you need to remember: A condenser microphone that requires phantom power will not work with an input that only supplies bias voltage.  Similarly, a condenser microphone that requires bias voltage will not work with a standard phantom power mixer input.

Know of any other audio myths that you want busted?  Leave a comment/suggestion and we may include it in a future blog post!

In this episode, we explore the top frequently asked questions from the Shure Applications Group. Chris Lyons is joined by Tim Vear as they discuss how to clean a microphone grill and how to hook up a mic up to a computer.

When we decided to devote this issue to dispelling common audio myths and legends, we had no trouble impaneling a group of experts. Culled mostly from Shure’s Applications Engineering Group, these individuals devote their days, and sometimes their nights, to setting the record straight. Chief among this talented group is Tim Vear, who served as our primary mythbuster and spokesperson.

Myth #1: A louder microphone is a better microphone.

False.

Some microphones are more sensitive than others but microphone sensitivity is not inherently related to quality. Condenser microphones are more sensitive than dynamic microphones, but in most musical applications when a mic is placed very close to the sound source, the sensitivity of a microphone is not important. There’s more than enough signal even from a less-sensitive microphone to give an adequate signal into a PA system.

If the microphone is overly sensitive, it just means you have to dial in more attenuation on the mixer channel so you don’t overload the mixer. If you’ve got a mic on a snare drum that’s 10 dB more sensitive than another mic on the snare, you’ll have to turn down the one that’s more sensitive.

Extra sensitivity is not related to the sound quality.

In many cases, “hotter” is equated with louder. In the days when neodymium magnet microphones were introduced, it was a common demonstration technique to line up several microphones, connect them to a mixer and set each channel level the same. Each microphone was tested and when it came to the neodymium magnet microphone, it was noticeably louder because the structure was more efficient than the alnico types.

Psycho-acoustically, listeners tend to equate louder with better and that’s been a common sales technique used in selling stereo speakers. If one pair in a store demo is turned up a little louder than the others, customers tend to think they sound better. Or are better. It’s the same with microphones. It’s a loudness difference, not a quality difference.

Myth #2: Microphones always sound better in the store.

It depends.

An in-store demo of a microphone or any other acoustic product is greatly affected by the acoustic environment of a store. (That’s why there are listening rooms.) If the store is noisy or quiet, if you’re listening to the microphone through loudspeakers or headphones, all of those factors change the perceived sound of the microphone.

A clever salesperson can set up a demo to favor a particular microphone or a loudspeaker. If you’re evaluating products in the store yourself and can control what you’re doing, you can normalize the levels and the EQ so that each microphone is getting into the system flat. Then, the only differences you’ll hear are the tonal differences of each microphone.

In-store demos are not really indicative of how the microphone will perform in real life. Ideally, you want to take a mic to a gig and use it in the environment you normally work in. Evaluate it that way.

Most people test the mic in the store wearing headphones (or listening through loudspeakers) and saying “Test, one two … test, one two” into the microphone. Because the sound of your voice reaches your ears directly through bone conduction, what you’re hearing is not just the sound of your voice through the headphones or loudspeakers, but the sound that is conducted internally.

To hear what the microphone really sounds like, you need to record your voice speaking or singing a phrase and then listen to it in playback. You can compare several mics that way and listen to the recording right in the store, wearing your own sound-isolating earphones or headphones. That will give you the best idea of what the mic really sounds like.

Myth #3: The SM58® hasn’t changed in 40 years.

False.

When the SM58 was introduced in 1967, it was aimed at broad cast applications for which it was not ultimately embraced. But it was discovered by the fledgling live sound industry where it quickly gained a reputation as a reliable, good-sounding and affordable mic for a huge range of applications. It maintains that reputation – undiminished – 40 years later.

The basic technology is the same – the diaphragm voice coil magnet assembly, the shape and size are pretty much the same as when it was first engineered.

Dynamic microphone technology hasn’t changed. Take the internal combustion gasoline engine. A 327 small-block Chevy engine is old technology. It was designed in the early 1960s and is highly regarded and widely used today because it is a proven design that offers great performance.

One of the things that makes this technology perfectly appropriate is that it is extremely stable over long periods of time. It’s going to sound and perform as well a year from now, five years from now, ten years from now and twenty years from now. And that goes right to the heart of why sound pros love these microphones. They’re extremely predictable. There’s a lot of value in knowing that this microphone is going to work.

The second part of this myth is false.

There have numerous improvements in reliability and manufacturability. There was a secondary tap on the transformer that was eliminated about 15 or 20 years ago related to a 50 ohm output impedance condition that was no longer a factor. The voice coil wire was changed to a copper clad aluminum to improve the solderability of the voice coil leads into the cartridge structure. The grounding mechanism for the output connector was changed. The paint formulations have been improved. The grille plating has been improved – the things that relate to long-term reliability have been changed incrementally throughout its history.

The sound quality of an SM58 is not a high-fidelity sound. It’s shaped in certain ways: the extreme low frequencies and the extreme high frequencies are rolled off. Those frequencies are outside the range of the human voice. If it were designed to pick up those frequencies in live sound applications, it would pick up a lot of undesired noise.

But within the vocal range, it has a characteristic rising response in the 2-10kHz range. It’s referred to as the presence rise or the presence peak – that sound characteristic, while not flat or high fidelity, is extremely useful in live sound applications because it boosts and improves the intelligibility of the human voice in the midst of other amplified sounds. That range is where the real color and identifying characteristics of a human voice exist and that is extremely useful in a vocal microphone.

Myth #4: Dramatic movement of the microphone by a lead vocalist is a useful technique. Great theater. Great sound.

False.

The level and sound quality of the human voice varies considerably with microphone distance from very close to very far away and all points in between. It is not conducive to a consistent sound quality in a sound system. Most sound engineers will try to get performers to stay pretty much the same distance from the microphone, whether that’s two or eight inches away.

The “trombone effect” of pulling the microphone away two or three feet back when a vocalist is singing a really loud note isn’t necessary or desirable. If the system is set up and equalized for a singer who is holding the microphone an inch away and suddenly he’s holding it eight inches away, the sound will be very thin.

Every time the distance between your mouth and the microphone doubles, you lose 6 dB of sound level at the mic. That’s the Inverse Square Law. If it’s two inches away (double the distance), you get 6 dB less. If it’s four inches away (double the distance again), you get another 6 dB less. At eight inches away (double the distance yet again), the level is another 6 dB less. This is a total of 18 dB less than the level at one inch away! This means that in order to get a consistent sound level, the engineer has to push the fader up 18 dB when the mic moves from one inch away to eight inches away. This is nearly impossible without causing feedback .

On the other hand, a mic held too close will boost the low frequencies. It’s called Proximity Effect.

It’s not usually possible to overload the microphone itself. Let the sound engineer control the dynamics if necessary and you’ll get a better sound.

Myth #5: Condenser mics aren’t as rugged as dynamic mics.

False.

In the days when this myth came into existence, the average condenser microphones were very expensive, studio-grade models. The microphone they were compared to might have been a dynamic like the SM58. If I take the ultra expensive, circa 1930s vacuum tube Telefunken microphone and I dunk it into a glass of beer or drop it on the stage ten times – or even one time – it will probably stop working. It’ll become a paperweight while the SM58 will survive all that.

Today, all our condenser microphones are engineered to hold up to exactly the same abuse as an SM58 – they go through the same exact environmental testing. Drop testing. Temperature testing. Humidity testing. Salt spray testing. Vibration testing. Electromagnetic testing. They have to pass the same battery of tests – and they do.

The SM81 was introduced around 1978 as a studio condenser microphone. But because it is made from a machined steel handle and has the same sort of milspec environmental capability as the rest of our microphones, it was quickly embraced by the touring sound industry. There are SM81s out there on tour today that are probably fifteen or twenty years old. You can drive over them with a truck. Drop them on the floor. Hit them with a drumstick. And the same is true of all our condenser vocal mics.

So, in the modern era, the fragility of Shure condenser microphones is just not true.

Myth #6: A wide-range, flat-response microphone is better than a shaped-response microphone.

It Depends.

For a sound source that has a very wide frequency range, you want a microphone that can reproduce it in a high fidelity manner. That’s what a flat response should do. The assumption is that whatever the destination of that sound, either a playback system or a live sound system, the mic will reproduce the range that you’ve gone to so much trouble to get.

The average rock and roll sound system is not a wide range flat response thing itself. So putting wide range flat response mics on the front end doesn’t get you much. You can’t hear the performance difference.

But with a very high quality sound system or a recording environment, yes.

Some sound sources like close-up pop vocals, electric guitar amps and snare drums have fairly narrow frequency ranges. There’s no reason to have a microphone that goes down to 50 Hz picking up an electric guitar amp or a voice. So a shaped response mic may be more desirable. Close-up vocals, instrument amplifiers and certain percussion instruments really can benefit from not flat, not super wide range response.

It’s completely dependent on the sound source and the environment.

Myth #7: There’s no way to clean a mic.

False.

We’re probably talking about vocal mics that take on a certain amount of bodily fluids during their normal lifespans.

The foam windscreen inside the grille absorbs most of the effluent that spews on microphones. If you want to clean that, you just remove the grille, wash it in warm soapy water, rinse it thoroughly in fresh water and let it air dry. That can be done many, many times before the foam disintegrates. But when that happens, you can just replace the grille. (Available at a nominal cost wherever Shure mics are sold.) We don’t recommend spraying anything (like a disinfectant) on the gr ille.

The cartridge is never really exposed to the kinds of things that might concern someone. Cleaning or replacing the grille pretty much restores the microphone to its original condition.

Myth #8: Blowing into or banging on a microphone will damage it.

False.

There’s no risk of damaging a microphone in either of these ways. But those kinds of noises are sometimes a problem for the sound system if it’s turned way up because those impulses can damage the loudspeakers. And either irritate or potentially damage the hearing of anyone in the room.

A more appropriate way to test the mic is to talk into it or sing into it at whatever level you’re using and let the sound engineer set the representative level.

Myth #9: Condenser microphones always sound better than dynamic microphones.

False.

In absolute terms, condenser mics have some characteristics that dynamic microphones don’t have. For instance, very wide frequency response, very flat frequency response and very high sensitivity. For an application that requires these things, a condenser microphone would be a better choice. But in that case, it might sound better because it captures a wider range of the original sound source in a more high fidelity fashion.

There are many sources that don’t benefit from the flatness or the frequency range of a condenser microphone. A good example is miking close up vocals for pop music. Its hardly necessary to use a microphone that has a frequency response from 20 hertz to 20 kilohertz to pick up the a sound that only has a frequency range of maybe 100 Hz to 14 or 15 kHz. The sound system that is reproducing it might not even have that wide a range.

Particularly with pop music, a flat frequency response is not going to give you the presence or the ability to cut through a mix of other amplified instruments like guitar, drums and so forth. For example, an electric guitar plugged straight into a sound system has a very dull, bassy sound. But when it’s plugged into a guitar amp that has a shaped response designed for that instrument, you get all of the brights and textures and exaggerated midrange response you want to hear in an electric guitar. A microphone with a shaped response works the same way and is often going to give you a better sound quality for that application.

Same for a kick drum — it doesn’t benefit from a flat response mic in contemporary or pop music applications. You want something with a little bit of shape to give it the oomph or the snap you need to define that drum. You’re not trying to get a high fidelity sound. You’re trying to get a particular sound.

There are numerous examples where a dynamic microphone has a more appealing or preferred sound. Snare drums. Electric guitar amplifiers. Kick drums. Close up rock & roll vocals. Certain percussion instruments. They all benefit from a dynamic microphone’s shaped response.

Myth #10: Some microphones have better reach than other.

False.

Reach is not a specification of a microphone. Mic users have a concept of reach as the ability of a microphone to reach out and grab the desired sound in the midst of some ambient undesired noise conditions. They believe that some microphones can pick up from farther away than other microphones.

The reality is that microphones do not reach out and grab the sound from a distance. They merely measure pressure variations right at the diaphragm itself. The microphone doesn’t “know” anything about what is happening at any distance from itself. For this reason, if you try to characterize a microphone’s “reach”, it’s almost completely dependent on the ambient acoustic conditions around the microphone.

Here’s an example: Take a microphone to the Superbowl on a Tuesday morning at 2AM in the middle of July. There’s nobody there. They’ve turned off the air conditioning and it’s a huge quiet box. You put your microphone at o ne side of the stadium and drop a nail on the concrete on the other side of the stadium. Yes, the microphone will pick up the sound of that nail a couple hundred yards away because there’s no ambient noise. Go back on Superbowl Sunday in the middle of the fourth quarter when the opposing quarterback is lining up to call the play. Put your microphone down on one side of the stadium, clear out the beer vendors and drop the same ten-penny nail on the concrete. Can you hear the nail? What changed? Same mic, same nail, same concrete, same building. But the ambient noise level is now 100 decibels higher.

The reach of the microphone, if you can even call it that, is mostly dependent on the ability of the microphone to pick up sound in the middle of all that noise. No microphone has a “reach” that is defined independent of ambient noise.

The one specification of a microphone that loosely corresponds to the concept of reach is directionality or the microphone’s polar pattern. The directional characteristic of a microphone describes how much sound it picks up from ambient sources compared to how much it picks up on-axis.

The numbers are there, but they’re not huge. The difference between how much ambient noise an omni-directional and a hypercardioid microphone will pick up in the same conditions is only about 6 dB. (The hypercardioid mic picks up 6 dB less ambient noise than an omni.) Because of the Inverse Square Law of Sound, if I double the distance between the sound source and the microphone, the level of the sound source drops by six decibels at this greater distance. The ambient noise stays the same. If an omnidirectional microphone picks up a certain ratio of ambient noise to on-axis sound at one foot away from a sound source, then a hypercardioid microphone can be used at two feet from the sound source and still pick up that same ratio. This is NOT because the hypercardioid is more sensitive to the on-axis sound but because it is 6dB less sensitive to the ambient noise.

In that sense, the hypercardioid has more “reach”. But neither one will work at great distances in the presence of any significant background noise. They just measure little pressure variations right at the diaphragm.

Myth #11: Wireless systems will fail starting in February 2009.

False.

DTV: February 17, 2009 is the completion date for transition from analog television broadcast to digital television broadcast (DTV). All broadcast television stations will be required to operate in what are now channels 2-51. Only DTV stations will remain on the air. The analog stations will be gone. The former TV channels 52-69 are going to be reallocated for other purposes; one of them is Public Safety, which will be using Channels 63, 64, 68 and 69. The rest of that spectrum will be primarily used by communications services in devices that resemble cell phones.

Wireless microphone or personal monitor system products that operate in these former television bands may begin to suffer more interference from these services. That doesn’t mean that the systems won’t work any longer. But users will probably have to change frequencies to avoid these new services.

There’s still likely to be a fair amount of open spectrum in different places around the country on some of the frequency ranges. In some places though, it may be difficult to operate as many systems as previously because there may not be enough spectrum for all of it. If users have frequency-agile systems, they’ll be likely to continue using that system with very few problems in the foreseeable future.

Shure will not sell equipment that operates on channels 52-69 after February 2009 and we haven’t sold equipment in that range for some time now.

DTV is completely separate from the White Spaces issue. The only common denominator is the date – February 17, 2009.

White Spaces: Even when all the remaining TV stations are in the range of channels 2-51, there will be plenty of open channels in most plac es. There won’t be 51 channels on the air in every city. But there may be 15 to 33 open TV channels scattered around the country in different cities. These are the licensed channels that wireless microphones and personal monitors currently occupy.

There is a White Spaces Coalition that includes Microsoft, Intel, Google, Hewlett-Packard and several other companies proposing that a class of consumer electronic devices operate in the unused portion or the open television channels. These devices would be unlicensed, that is, anyone could operate such a device without obtaining an FCC license. Cell phones, cordless phones, and wireless laptop computers are examples of unlicensed devices. Historically, the nature of consumer electronic devices has been to heavily populate the unlicensed bands in which they have been allowed to operate. This includes the 49 MHz band, the 900mHz band, the 2.4 GHz band and several others. The concern is that new devices could disrupt professional audio users because their operation would be unpredictable.

The FCC’s issue is deployment of rural broadband Internet access, using unused TV channels to provide service. Cable is expensive to run to these areas and satellite is a downlink only, so rural high-speed broadband access via wireless transmission offers a good solution.

Shure, as part of a group of concerned audio users and manufacturers, has organized a very strong campaign within Congress and the FCC to make sure that the interests of wireless microphone users are protected. There are various technical schemes that are being proposed for these unlicensed devices to be able to detect the operation of current users of the spectrum in order to avoid interference. Pending the outcome of FCC testing, the initial target date proposed for introducing these devices is February 18. 2009 and that’s the only nexus with the DTV issue.

The task of the FCC is to weigh the needs of the current users of the spectrum (broadcasters and audio professionals) versus potential new users (consumers)–and make sure that the incumbents are not disrupted. We believe that wireless microphones will get appropriate consideration from the FCC.

The best advice for wireless audio users is to purchase frequency-agile systems.

Note: Shure posts White Spaces Updates regularly on our website, a good way to stay up-to-date on the most recent developments.

Audio Dictionary

Effluent
Something that flows out.

Gain Before Feedback
The amount of gain that can be achieved in a sound system before feedback or ringing occurs.

Gigahertz (GHz)
One thousand million Hertz

High Fidelity
Sound reproduction over the full range of audible frequencies with very little distortion of the original signal.

Inverse Square Law
States that direct sound levels increase or decrease by an amount proportional to the square of the change in distance.

KiloHertz (kHz)
A measurement of frequency equal to 1000 Hertz

Megahertz (MHz)
A million Hertz

MilliHertz (mHz)
One thousandth of a Hertz

Presence Rise or Peak
A rising response characteristic in the 2-10kHz range

Proximity Effect
Change in the frequency response of a directional microphone as the sound source is brought in close proximity to the microphone. The result of the change is a disproportionate increase in the bass response.

Psychoacoustics
The perception of sound

Potential Acoustic Gain
A measure of the amount of gain before feedback that can be obtained with a sound reinforcement system that’s based on the number of open microphones and distances from source(s) to microphones and listener(s), as well as speaker distances from listener(s) and microphones. These parameters are basically plugged into an equation that involves the application of the inverse square law.

White Spaces
Policymakers use this term to describe a rule making in which the FCC may allow unlicensed devices to use future unoccupied TV channels.

We take a look at the history and technology of the legendary SM57 and SM58® microphones in this episode. A few highlights from the show include: the “drop test” and a testimonial from devoted SM58 user Henry Rollins. Tim Vear from Shure’s Applications Department is our guest.

Tim Vear from Shure’s Applications Engineering department can talk wireless with the best of them. In this installment, Tim shares his knowledge of wireless technology and television airwaves…past, present and future.

In this episode, we are joined by Senior Applications Engineer Tim Vear to get a little insight on the different types of wireless antennas and the proper way to place them for optimal performance. Tim is Shure’s resident wireless expert and has enough knowledge on this topic to fill hours and hours of podcast shows. Luckily, we were able to talk him into only providing the highlights of his presentation.

At the conclusion of this podcast, if you should still feel the hunger for more wireless antenna information, check out our FAQ Database or contact one of Shure’s applications engineers at support@shure.com to help curb your appetite for wireless antennas.