Form Factors – Narrowing the Field

The sound reinforcement requirements of a church are different than those of more typical live performances, so once you’ve decided what type (dynamic or condenser) and polar pattern (omni or uni) you’re going to need for each application – pastor, soloist, choir, worship leader, praise band – there’s the form factor to consider.   This is actually pretty simple because the solutions are fairly straightforward.

We’ll look at them one by one.

Lectern Mic

Lectern

One of the most common microphones used in houses of worship are lectern or podium microphones.  Gooseneck microphones are recommended since they position the mic up high and close to the speaker’s mouth.  These are usually cardioid condenser microphones since they are very small and unobtrusive and also since their greater sensitivity allows the microphone to be positioned 10”-14” and a little off-center from a speaker’s mouth.

One of the reasons that the mic is positioned off-center is the undesirable popping sound of plosives (p’s and t’s).  When the mic is off to the side, the air blast that causes those plosives will go past the microphone rather than right into the microphone.  Using a windscreen also helps.

Tips:

• Make sure you only have one microphone on at the lectern, to minimize comb filtering
• Use a pop filter and a shock mount to minimize unwanted sounds.
• Turn off unused microphones

Boundary Mic

Altar

The altar is another area that you may need to mic.  In that case a gooseneck microphone may not be aesthetically pleasing, so boundary microphones – usually condenser types – are the typical solution.

Tips:

• Try not to place them too close to the edge of the altar since they’re limited to a 60o vertical pick-up angle.   If the microphone isn’t placed deep enough into the altar, you run the risk of the speaker talking over the microphone instead of into it.
• Turn off unused microphones.
• Position speakers within 24”-36” of the mic.

The low profile of boundary mics also subjects them to the risk of having speakers place objects over them and since they’re typically sensitive condenser-type mics, they’re susceptible to noises like page turning.   Still, they’re usually the best choice for altar applications.

Lavalier Mic

Lavalier

One way to make sure that the pastor or worship leader is heard clearly is to use a lavalier microphone where the speaker or singer can move around freely without concerns about being picked up by the mic.    Here’s where you want to think about polar patterns

Tips:

• My choice is the omnidirectional lavalier microphone because you don’t need to be as concerned with placement – you can aim it in any direction and there’s no proximity effect.    There’s minimal pickup of wind or cable noise – and they are less susceptible to plosives. Omni lavaliers sound natural and they’re the easiest to place.
• On the other hand, if you’re experiencing gain before feedback problems, you may need to go with a unidirectional lav microphone, sometimes with a cardioid or even a supercardioid pattern   It will also help to reduce background noise in a nosy environment. Remember that they’re more susceptible to cable noise, plosives, wind noise, proximity effect and other things that will color the sound quality and add more artifacts than you desire.

If you can make the omni work, that’s the way to go.   Placement is usually about 8” below the mouth in the center, because the pickup will be affected if the speaker moves his head from side to side.   That’s a common problem with any lav mic. If possible, it’s also beneficial to use a windscreen.

Tips:

• Secure the cable to the wearer’s clothing to eliminate cable noise.
• If multiple mics are used when the speaker approaches the lectern or alter, remember to turn unused mics off, otherwise comb filtering may result.

Countryman Mic

Headworn (Headset)

The headworn mic is by far preferred over lavaliers in most church applications these days, though some people don’t like to wear anything on their heads. There are some very tiny headworn microphones that hook over one ear and are barely noticeable.

They take care of just about all the problems experienced with lavalier microphones and offer some significant advantages:

• Gain before feedback is much better – the mic is right next to the speaker’s mouth. Since the mic moves with the speaker’s head, the sound level and quality don’t change.
• They are omni condenser mics with multiple color options so skin tone can be matched – with single ear and dual ear options.
• Placement is easy – left or right side doesn’t matter.
• Overall, you’ll experience more consistent sound quality, fewer feedback problems and better gain before feedback.

The Choir and the Praise Band

Here are a few quick tips for miking the choir and members of your praise band. Volumes can be – and have been – written on various techniques for achieving a specific sound, but this overview will get your started.

The Choir

Stand-mounted or hanging mics can be used to pick up the choir. In almost all cases, these are condenser mics.  They have a flatter, natural frequency response and are sensitive enough to work well at a distance.

Try to mic the choir as if it’s an acoustic instrument.  It’s the same way you’d mic an orchestra.   You’re trying to capture the ensemble without coloring it too much.  Most often, these are unidirectional condenser mic.

Tip:

• The 3-to-1 rule applies. Typically you’re going to position the mic 2-3 feet in front of the choir with the most sensitive point of the mic aimed toward the back row of the choir, and adjacent mics about 4 – 6 feet apart from each other.   That helps provide even coverage because the most sensitive point of the mic is aimed at the singers who are furthest and the singers who are closest are positioned at a less sensitive point, so you’ll get nice, even coverage.

Tip:

• If you’re using hanging mics, you need to be careful not to hang the mics over the heads of the singers, rather than 2’-3’ in front of their mouths, aimed at the back row.  Failing to do that will results in a dull, dark sound with very little sound level reaching the microphone. You need to be able to mic their mouths (the sound source) and not the top of their heads.

Tip: 

• It is best to use as few mics as possible and avoid as much overlap as possible.   If you need to use more than one and the first one is 2’ away from the choir at an 130o angle, the way to position it is to follow the 3-to-1 rule and position the next mic 6’ away.   And if that’s not enough, place another microphone 6’ feet away.

The Congregation

Miking the congregation isn’t a musical application but it is something that comes up since adding ambient sound creates a more natural mix for broadcast feeds or recording.    It’s similar to choir miking since you can think of the congregation as a large ensemble.

Tips:

• You will probably want to use some type of unobtrusive unidirectional microphone and only for recording or broadcast purposes where you need to add some ambience.
• Don’t mic the congregation for sound reinforcement purposes.   If you need to hear an individual in the congregation, the best way to do that is with a wireless handheld.

The Praise Band

Here are some basic member-by-member suggestions:

Vocals

• Handheld or headworn mic.
• Unidirectional – dynamic or condenser – depending on the sound quality you’re trying to achieve.

Look for a good shock mount that eliminates some of the handling noise. The SM58, for example, has a very good shock mount. You can tap on the microphone and you won’t hear very much.  A cheap mic can sound like a freight train when you do the same thing.

Electric guitar amp

• Dynamic or condenser
• Make sure the sensitivity of the condenser mic is designed for the application.

Beta 181 is a good choice. You can hang it over the top of the guitar amp in front of the speaker without needing a mic stand.

Drums 

• Dynamic mics for snare and tom-toms, which handle the high SPLs in these applications.
• Condenser mics are useful for overheads and cymbals.
• Percussion mics might be condensers as well for general area miking applications.
• Kick drum: Beta 52A is the Shure mic designed specifically for use as a bass drum mic, but a Beta 91A boundary microphone can also be a good choice for its low-profile design and set-up ease.
• Snare drum: Good choices include SM57 or Beta 57A mics.  Place the boom-mounted mic in front of the kit, a few inches from the snare drum edge, next to and just above the high tom head for a natural sound.
• Toms: Beta 56A or Beta 98AMP mics can be used.  For the best isolation, consider placing a microphone inside each tom-tom.
• Overheads: A Beta 181/C or PG81 mic can be positioned about a foot above the drummer’s head or a matched pair of either model can be used for stereo miking.

Grand or upright piano

• Condenser mics for flatter, more natural frequency response.
• Stand-mounted or boundary mics are also good choices. Boundary mics can actually be taped inside the lid of the piano.
• KSM137 is a good choice for a stand-mounted mic.  It can withstand high sound pressure levels and it’s also available in a stereo kit, making it ideal for X/Y configuration miking preferred by many live sound engineers.
• For mounting inside the piano, you can use a Beta 91A cardioid condenser microphone. This microphone will work for both a grand and upright piano.

It all comes down to this

What’s really important is knowing how the mic sounds, using your ears to chose the right one and then knowing where to place it.  Moving the microphone just a few inches in one direction or another can improve the sound quality dramatically. Time for experimentation is time well spent.

One way to do this at home is to check out the Mic Listening Lab where you can listen to many different types of mics on many different instruments (including vocals) so that you can hear the differences for yourself. You’ll also find an “Audition This Mic” link at the bottom of product pages on the Shure site.

Choose the right mic, put it in the right place, keep it as close to the sound source, use as few mics as possible, turn off unused mics and trust your ears.

ABOUT GINO SIGISMONDI: Gino Sigismondi has been active in the music and audio industry for nearly twenty years. Currently managing the Systems Support department, Gino brings his years of practical experience in professional audio to the product training seminars he conducts for Shure customers, dealers, distribution centers, and internal staff. He is the author of the Shure educational publications “Selection and Operation of Personal Monitors,” “Audio Systems Guide for Music Educators,” and “Selection and Operation of Audio Signal Processors.”

Gino spent several post-college years as a live sound engineer for Chicago-area sound companies, nightclubs, and local acts. He continues to remain active as a musician and sound engineer, expanding his horizons beyond live music to include sound design for modern dance and church sound.

Different Transducer Types

A transducer is anything that can take one form of energy and convert it to another form of energy. That’s what a microphone does.

A mic measures the variations in air pressure that we recognize as sound waves and changes them into electrical signals that can be manipulated for sound reinforcement, for recording purposes or for broadcast.  The acoustic wave is converted into an analogous electrical signal. All microphones do this, but they do it in different ways.  So a microphone is really just a measurement device – measuring variations in air pressure and providing a corresponding electrical signal.

As the front end of the audio system, the microphone is one of the more important elements in the signal path.   If you don’t capture the sound accurately before it gets into the electrical domain, there really isn’t a great way to fix it later on. The more of that you do on the back end with processors and other tools, the more work is involved and the less natural it will sound.  If you choose the right mic and put it in the right place, everything that follows will be that much better.

Dynamic and condenser mics are most popular types.  There are other types – ribbon mics, crystal mics, control magnetic, and carbon mics, for example – but those are largely historical, so we won’t cover them here.

The most popular is the dynamic mic.  It’s a very simple device – rugged, reliable and in most cases, not very expensive.   Sound waves move a thin, lightweight diaphragm, typically a very thin layer of a Mylar®. The physical energy required to make this diaphragm move is not very great.

Cutaway of a Dynamic Microphone

The diaphragm has a coiled wire attached to it and is suspended in a magnetic field.  A basic property of electricity is that when a wire cuts through a magnetic field, a current is induced in that wire.  As sound waves strike the diaphragm and move it back and forth, the coil also moves back and forth in the magnetic field, inducing current and a corresponding varying voltage in the wire.   Those wires go out to the connector at the bottom of the mic. Some microphones might have an output transformer to step up the impedance and provide a little more signal, some don’t. That’s the basic structure of a dynamic microphone.

It’s a completely passive device, so there’s no additional power needed to get it up and running.  Plug it into your system and you’re good to go.  Because they are such simple devices, they’re not very expensive, they’re very reliable and they’re hard to kill.  Think SM58® and SM57.

There are some limitations, of course.  They’re not very sensitive.  It takes more energy get that mass of the coil that’s attached to the diaphragm moving so they’re better for up-close applications and loud sound sources.  They’re not very good for miking sound sources from far away, like a choir for instance.

They’re nearly impossible to overdrive.  A human being can’t create enough sound pressure level to overdrive a dynamic microphone.  There is no way, for instance, that a singer can destroy an SM58 by singing too loud.  There may be some distortion at the input of the mixer if its gain control is set too high, but the problem is not happening at the microphone.  You’d have to mic the space shuttle for something like that to happen.

Most dynamic mics sound pretty good, but there’s a limitation in frequency response in terms of how much high and low frequency it can pick up.

Cutaway of a Condenser Microphone

Condenser microphones are a little more complicated.

One critical difference is that the diaphragm of a condenser mic does not have the mass of a coil hanging off of it.  The actual diaphragm is metalized, usually gold-layered or gold-sputtered and the diaphragm is tensioned over an air gap above a charged metal backplate.

When the sound wave strikes the diaphragm, it doesn’t have to work as hard to move it because there’s no mass of coil attached to it – and that’s one reason why condenser microphones are more sensitive.   They’re designed for quieter sound sources.

The output of a condenser microphone is much lower and the impedance is much higher, so there are some additional electronics – specifically, a microphone pre-amp – that’s part of the mic design. The pre-amp requires phantom power, supplemental voltage that powers up the electronics of the condenser microphone.  Phantom power is typically supplied by the mixer the microphone is connected to.

If you don’t provide a condenser microphone with phantom power, it simply will not work.   It’s a call we often receive at Shure from people who are accustomed to using a dynamic mic like an SM58 but purchased, for the first time, a $300 condenser mic.   They plug it into their sound system and it doesn’t work.   This leads to a longer discussion of phantom power and a suggestion that they turn on their mixer’s phantom power switch.   It’s an important detail to remember. There are a few condenser microphones that will run off a battery, but this is far less common.

They’re more sensitive to environmental conditions and they’re more expensive than dynamic mics because there are many more internal electronic components in their design.   But on the flip side, they’re more sensitive and offer a wider frequency response so they’re more natural sounding.   However, due to the active electronics that are part of condenser mic design, it is possible to overload or cause distortion in the microphone. Some condenser microphones are equipped with a “pad” that can be engaged to reduce the sensitivity of the microphone when used with loud sound sources.

Frequency Response

This can be divided into two categories – and really, it’s just about how the microphone sounds:

Shaped Response – can take many different forms.

The X-axis in this diagram shows the frequency of human hearing, from 20 Hz to about 20,000 Hz.  The Y-axis shows the output level of the microphone. You can look at the different frequencies to determine how much signal that particular mic is putting out.   You’ll notice at some frequencies, the output of the mic is lower or less sensitive and on others, the output of the mic is higher.   This can provide an advantage in certain scenarios.

For example:  If you’re looking at the 2-6 KHz range, the SM58 mic is more sensitive and has more output.  This is good because this is the range of most human speech where consonants can be heard.  Consonants define speech intelligibility.   In a church application, the message is the most important thing – so it’s important to have a microphone with good sensitivity in this range.

Now, look at response in the range below 100 Hz. The response drops off pretty dramatically.  In the case of the human voice, that’s OK unless you’re trying to mic a bass singer in a gospel quartet. What happens in that range is mostly unwanted noise, wind noise, handling noise, vibration, so if you have a mic that rolls off a lot of that, it’s beneficial for cleaning up the overall sound quality.   Response below 100 Hz is usually unnecessary unless you’re miking a grand piano, bass drums or the occasional bass singer.

Flat Response – is just what it sounds like.  The output of the microphone is pretty much the same across all frequencies.

It will pass everything along, whether or not it’s needed or desired.  It’s a very natural sounding and very uncolored frequency response.   For acoustic instruments, for example, where you don’t want to alter the sound in any way, a flat response mic might be the best choice.

Which response you need really depends on what you’re miking.  A wide-ranging flat response mic will pick up sounds that you don’t necessarily need and it won’t color the sound coming out of it.

Directional Response- This is how the microphone responds to sounds coming at it from different directions.  There are two categories:

Omnidirectional – sound coming from all directions
Uni-directional – sound coming from one direction

Bi-directional is another, less common category that refers to a mic that picks up sound from two directions, but we’ll focus on two that you are most likely to encounter.

Omnidirectional (“omni”) mics are sensitive to sounds coming from all directions.   They have a coverage angle of 360o so it doesn’t matter where the mic is pointed.   The response will be the same. Omnidirectional microphones are good for speech applications, as lavalier or headset microphones. In this case, they offer the most “uncolored” response (see proximity effect below), and since you don’t have to worry about picking up the drum kit, the lack of off-axis rejection isn’t really a concern.

Unidirectional (“uni”) mics take on a couple of different variations, the most popular of which is the cardioid pattern. It has a heart-shaped pickup pattern; that’s where the “cardio” comes from.  When you look at the diagram, you’ll see that there’s very little pickup 180o off the center.

The cardioid pattern is designed to capture the sound source you want to capture and reduce pickup of everything else, since it effectively rejects off-axis sound.  On a stage with a lot of sound sources and a lot of noise, it’s very beneficial compared to an omni which will tend to pick up everything. Since the cardioid mic is less sensitive to other sounds, like the sounds coming out of loudspeakers, it allows you to get more gain before feedback than you would with an omni.

Like everything else in audio, there are some trade-offs.  One of these is proximity effect, something that every unidirectional mic exhibits. That’s the boost in low frequencies as you move closer to the microphone.  Sometimes people like this effect and other times that bass response will muddy things up.   Omni mics don’t product this effect since the frequency response is the same no matter how far the sound source is from the mic itself.   Cardioid mics are also more susceptible to handling, wind noise and vibration.

Supercardioid and hypercardioid are even more directional.  There’s even greater rejection at the sides but a little bit more pickup in the null area (at the back of the microphone).   The overall sensitivity to ambient sound is less than even a cardioid mic.   An experienced vocalist in your church can really benefit from this type of tight polar pattern, but a less experienced singer who moves the mic around in a theatrical fashion will run into problems.

Keep in mind that there’s never a one-size fits-all option.  It all depends on what sounds best for your application.

The Myth of Microphone Reach

One common misconception is that directional microphones reach like a zoom lens on a camera – that you can take your viewfinder and focus on something far away and bring it closer. Microphones don’t work that way.

Sound waves are much longer than light waves and microphones are not able to bend those waves to bring them closer. Microphones don’t have a reach associated with them. What that means is that you need to get the mic as close as possible to the sound source for a couple of reasons:

1. The microphone is not going to go out and isolate a particular sound.
2. Sound waves follow the inverse square law.  That says that the energy of a sound wave drops as it spreads out in space. Every time you double the distance between the sound source and the microphone, you lose 6 dB of signal, which is quite a bit. If I move the microphone one foot away, the drop is sound is noticeable. If I move it from 1 foot to two feet away, that’s a 12 dB drop which will be perceived as more than half as loud.  So be aware that when you’re moving microphones further and further away, you are losing a lot of the direct signal.

What this graphic shows is that there’s a certain amount of noise and reverberation in any given room. That’s a concept known as critical distance which is the distance at which the direct sound of what you’re trying to mic and the ambient noise and reverberation become equal.  When your microphone is beyond that critical distance, you’ll hear all the ambience in the room at a level equal to the direct sound.  It’s the sound that some people describe as being in the ‘bottom of a barrel’ or sounding like a ‘tin can’. Every room will be different and if you don’t want to have to calculate what the critical distance is for every worship space, just try to remember to keep the microphones as close to the sounds sources as you can.

Another phenomenon you may experience is comb filtering which is where the audio signal takes multiple paths to reach the microphone, possibly reflecting off a tabletop or a lectern and having those reflections combined back in the microphone itself.    When that happens, the frequency response graph looks like a comb – that’s where the term comes from.   It has a very hollow, phase-y sound that’s not very natural and can really be distracting at times.   It’s another reason to keep the microphone close to the sound source, so that the direct sound will be much louder than the reflected sound.  It’s also a good argument for longer gooseneck microphones in lectern application because it keeps the mic further away from surfaces and closer to the speaker’s mouth.

You can also experience electronic comb filtering.  This happens when there is more than one microphone picking up the same sound source.  It can easily happen in a choir application.  When the same sound source goes to two different microphones and those mics are combined back in the mixer, you end up with the same comb filtering frequency response effect.

How you deal with electronic comb filtering is by following the 3-to-1 Rule.   It’s a good rule to remember in sound applications where more than one mic is being used.  It states that for every unit of distance from the mic to the sound source, the next microphone should be three times that distance away.

Feedback

It’s a common problem in many sound systems.  But it’s not the fault of the microphone. Feedback results from the interaction of all the components in the sound system.

Here’s what’s happening: the sound source goes into the microphone and the microphone signal goes into an amplifier and then a loudspeaker where it’s made louder. That same sound comes out of the loudspeaker and is picked up by the microphone again – it forms an audio loop that results in the sound or sounds we know as feedback.  You can’t buy a microphone that “doesn’t have any feedback in it”.

Tips for avoiding feedback:

• The way to combat feedback is to keep the microphone as close to the sound source as possible.
• Keep the mics as far away from the loudspeakers as possible.   If you can keep them separated from the loudspeakers, it’s less likely that they will pick up the sound and create a feedback loop.
• Lower the speaker output.
• Move the loudspeaker farther away from the microphone. Each time this distance is doubled, the sound system output can be increased by 6dB.
• Move the loudspeaker closer to the listener. Each time this distance is halved, the sound system output will increase by 6dB.
• Use in-ear monitoring systems in place of floor monitors.
• Acoustically treat the room (if possible) to eliminate hard, reflective surfaces like glass, marble and wood.

Some people think using unidirectional microphones will solve their feedback problems, but it’s actually less effective than many of the suggestions above. EQ can also be used and room acoustics are also a factor, but in most cases, following the first three tips here will go a long way in reducing feedback problems.

ABOUT GINO SIGISMONDI: Gino Sigismondi has been active in the music and audio industry for nearly twenty years. Currently managing the Systems Support department, Gino brings his years of practical experience in professional audio to the product training seminars he conducts for Shure customers, dealers, distribution centers, and internal staff. He is the author of the Shure educational publications “Selection and Operation of Personal Monitors,” “Audio Systems Guide for Music Educators,” and “Selection and Operation of Audio Signal Processors.”

Gino spent several post-college years as a live sound engineer for Chicago-area sound companies, nightclubs, and local acts. He continues to remain active as a musician and sound engineer, expanding his horizons beyond live music to include sound design for modern dance and church sound.

Just when we all adjusted to 2009’s FCC regulations involving the use of wireless microphones and mobile devices in the TV band, along comes a new wrinkle: the incentive auction.  This is not, repeat not, cause for alarm.  In this post, we’ll break it down into its simplest elements – explain the basic concept, survey the changing landscape, share the expected timeline and diffuse some common misunderstandings about how a spectrum change is likely to affect you and your wireless gear.

The FCC is under intense pressure to reallocate even more spectrum for mobile broadband. The rising popularity of smartphones and tablets has placed an additional strain on the currently available spectrum.  Consider, for example, the fact that smartphones use 35 times more spectrum than traditional cell phones and tablets use 121 times as much.  So the FCC is looking for innovative ways to open up additional spectrum, with the loftier goal of “spurring economic growth and maintaining the country’s mobile leadership.” Legislators are aware of these issues and recently took action to address them.

The bill granting special authority to the FCC was signed into law on February 2012.  It gave them permission to launch a one-time incentive auction that will repurpose some of the broadcast television spectrum. The basic premise is pretty simple: broadcast stations can elect to give up some of their assigned spectrum (either by moving to a different channel, sharing a channel with another station, or going off the air entirely) and offer them, through the FCC, to the highest bidder.  When the incentive auction is complete, the FCC will reallocate the cleared portion of the TV band spectrum to the auction winners.

How it Works. Courtesy: FCC LEARN site

Forward, Reverse and Repacking

Here are some terms you are likely to run across in coverage of the incentive auction.

Reverse Auction

The reverse auction is where broadcasters will establish their price to voluntarily relinquish spectrum rights in exchange for a portion of the proceeds from the forward auction.

Forward Auction

The forward auction is where the potential users of repurposed spectrum bid for new flexible-use licenses. The FCC is familiar with forward auctions in the spectrum context, and has been conducting them for nearly two decades.

Repacking

Repacking involves assigning channels to the broadcast television stations that remain on the air after the incentive auction… This process considers only a reassignment of channels, not geographic moves of stations; however, a station that opts to channel-share may have to move its antenna to a new geographic location – i.e., its sharing partner’s tower.

NRPM

This is the Notice of Proposed Rulemaking that forces government agencies (FAA, FCC, EPA for instance) to listen to comments and concerns of people whom the regulation will likely affect. The Notice detailing the FCC’s options for the auctioning of TV band spectrum “Expanding the Economic and Innovation Opportunities of Spectrum Through Incentive Auctions” runs 200 pages and included milestones shown in the timetable below.

Incentive Auction Timeline. Courtesy: FCC LEARN site

The Major Players

Wireless carriers are the primary proponents of the repack and auction plan, and, as the forward auction bidders, will be the likely beneficiaries.  Not to be overlooked is a profit opportunity for TV stations and the government. Some of the auction proceeds (estimated at approximately $25 billion) will be shared with TV stations participating in the reverse auction, some will be used to build a nationwide public safety communications network in the 700 MHz Band, and costs incurred to broadcasters from repacking will have to be reimbursed. The remainder of the proceeds will be deposited in the U.S. Treasury.

On the other side, the tech industry – Google, Microsoft, the WiFi Alliance, among others – cite the danger of putting power in the hands of a very few, very large companies who can afford to license their slice of the spectrum and use it for only those devices and services they market.  This group believes that free and open access stimulates innovation, investment, and job creation, as companies of all sizes develop new products and services.  They are lobbying for portions of the Band to be set aside for unlicensed use — similar to the allocation of the 2.4 GHz band for Wi-Fi and Bluetooth and the recent White Spaces initiative.

Professional audio interests, from trade organizations such as the National Association of Broadcasters to the country’s major sports leagues to the largest content producers, speak to the impact on wireless microphone users.  These entities remain vocal in their position that they have recently given up over 100 MHz of spectrum during the 700 MHz band reallocation, and that wireless microphone operation in the TV Band must be protected going forward.

http://apps.fcc.gov/ecfs/document/view?id=7022130172

http://apps.fcc.gov/ecfs/document/view?id=7022130256

Shure is at the forefront of efforts to maintain adequate spectrum for professional audio and is actively involved in the Incentive Auctions proceeding.

How It Affects the Wireless Microphone User Today

Since there’s a risk of confusion for wireless users, Shure Notes asked Chris Lyons, who has been leading training sessions at Shure on the general subject of spectrum issues, for his insights.

Which spectrum will be auctioned?

The FCC has suggested a few different sections of spectrum for the auction.  The most likely is a section in the upper part of the existing TV band, beginning at TV channel 51 and extending downward.  How much spectrum is auctioned depends on how many TV stations volunteer to participate, which will likely vary in different cities.

When will the auction take place?

The FCC hopes to conduct the auction in 2014, but has not announced a specific date.  Commissioners have stated clearly that this is the most complex spectrum auction in world history and could be subject to unforeseen challenges.

Assuming that enough TV stations participate and the incentive auction takes place, how long will it take the FCC to repack the TV Band?

Repacking the TV stations into a smaller TV band is the hard part of the process, and could take a few years.  The repacking process is as complex as the DTV transition was, which ended up taking 10 years.

Will any pro audio manufacturers take part in the forward auction?

No, it’s not feasible (financially or technically) for a manufacturer like Shure to own and administer a piece of spectrum solely for its own users.

In 2009, wireless systems that operated in the 700 MHz band were no longer allowed.  Could reallocation of the TV Band make today’s wireless systems obsolete?

Wireless microphones (as well as personal monitors, production intercoms, and similar gear) that are in the spectrum that is auctioned will have to stop operating at whatever date is set by the FCC.  This means that those systems will need to be replaced with units that operate in the spectrum that is still open for wireless mic use.  Failure to comply with FCC rules (just like IRS or EPA rules) is illegal and subject to enforcement action.

Should I be doing anything now to get ready for post-repack landscape?

At this point, the most valuable thing to have is information.  Every facility or venue that uses wireless microphones needs to appoint someone to keep up with this issue as it progresses.  If you own equipment in the upper part of the TV band, it would be wise to begin budgeting for replacement equipment, so that you’ll be ready to act when the available TV channels in your area are finalized.

How can I stay informed of what’s going on?

The FCC’s LEARN Program is quite user-friendly, and spectrum issues are always reported on their blog.  Shure’s website and publications also report significant developments.  And our Product Support department is always a good resource for guidance.

…That’s what you hear as the 55th Annual GRAMMY Awards go live to air in the packed to capacity Staples Center in downtown Los Angeles. However, before all of the applause and packed seats of onlookers, the GRAMMYs go through a rigorous schedule of rehearsal and timed perfection. What you at home see on TV is the result of A LOT of hard work. The madness that is GRAMMY week is bigger than any single concert you’ve been to, and it is where we spent most of last week as things began to take shape for music’s biggest night.

Prior to entering the bowels of the Staples Center, Shure once again sponsored the Producers & Engineers Wing GRAMMY Week Celebration honoring Quincy Jones & Al Schmitt. Hang on… prior to that, we made a stop to In-N-Out Burger in honor of Mr. Mike Lohman, who could not be with us on this trip. It was worth the wait. It was delicious. Why don’t we have this in Chicago? Back to the GRAMMY stuff…

Making our temporary home in Studio B of The Village Recording Complex, Shure served up some fresh seafood and the latest in wired mics and headphones. It was amazing to hear so many stories about Shure mics being used on classic recordings from the engineers and producers in attendance. The Super 55 tree, as we have dubbed it, was a bit of a challenge to construct, but I’m happy to say that it made through the entire evening without incident! Aside from being in such esteemed company, the highlight of the night for me was watching a few very critical ears try on the Shure SRH940 and SRH1840 headphones and be completely blown away! That and the countless offers that were made to purchase the SM7B on site or the questions about it being included in some sort of raffle. Most visitors to Studio B had something positive to say about the sleeper hit that is the SM7B.

Okay, so breakfast at the hotel was not that good and VERY expensive, not doing that again. Never mind that, we were making our way to the tunnel into the madness I referenced (there it is on the left) to join in the fun of rehearsals, day one. By the way, the “we” in question is Ryan Smith, Artist Relations Nashville and Jenn Liang-Chaboud, Market Development Senior Specialist. There is so much that goes into this show and everything is in the same place every year… good thing, as I’m just starting to get this whole thing down. As we arrived to the backstage area, we were called into a meeting with production who were concerned about how much “fun” the band fun. was going to be having on GRAMMY night. The “fun” in question was the rain curtain you all undoubtedly witnessed, where the band, all of their instruments and microphones were all drenched in a rain storm. Of course there was concern that the mics may fail if exposed to that level of water, but we were never all that concerned… that’s how we test this stuff! Aware of production’s concern, we immediately put a few phone calls in to the home office in Chicago to have back up transmitters and capsules sent out the next day (thanks to all of the Shure people who came through in the clutch)! Needless to say, we never needed back ups. Those mics you saw on Sunday night were the same mics from rehearsal and dress rehearsal… that’s multiple rain storms!

Making our way around the arena, we found some familiar faces in Mike Parker and Tom Pisa working stage left and stage right respectively. We were also happy to see some familiar product in place as the exclusive in ear monitor system for all artists performing at the GRAMMYs. Twenty-four channels of Shure’s PSM 1000 was once again the preferred choice by production and most of the artists that performed this year. Rehearsals did not begin until about 1:30 pm on day one, so it gave us some time to catch up with everyone and provide them a little Shure swag in the meantime. It actually got cold there in California… nothing like what Chicago was going through, but even a hooded sweatshirt (this year’s swag item) struggled to keep me warm. I did refuse to opt for the winter coat stashed back at the hotel… I’m from the midwest and way too many people would be a little upset and quite possibly revoke my man card if I was discovered wearing a winter coat in California.

So anyway, as the rehearsals moved into full swing, lots of Shure mics were in some pretty important positions on stage. It was nice to see the KSM313 on the guitar amps of the Lumineers and Jack White, that’s quickly becoming everyone’s favorite mic for guitar amp… it looks pretty sweet, too! On vocals you saw Taylor Swift on an Axient Wireless System with a Beta 58, fun. on UHF-R Wireless with Beta 58s, Mumford & Sons on Beta 58As, Justin Timberlake & Jay-Z on UHF-R Wireless with SM58s… a last minute vocal mic change put Justin on a Shure mic for the evening and I thought he sounded pretty damn good on it too! Adam Levine from Maroon 5 was on a UHF-R with a Beta 58 when he joined Alicia Keys onstage, The Black Keys rocked on their SM58s. Kelly Clarkson brought the house down on an SM58! The Lumineers had everyone singing along on SM58s. Jack White tore up the stage while on an SM58. The Levon Helm tribute featured amongst others, Mavis Staples on a UHF-R SM58, Brittany Howard on a UHF-R SM58 and Mumford & Sons on UHF-R SM58s. Juanes sounded amazing on a UHF-R KSM9 and Frank Ocean debuted a new track on a UHF-R SM58. The night ended with two hip-hop icons blazing up the stage as LL Cool J and Chuck D performed on UHF-R SM58s.

All in all, a pretty good selection of Shure mics helped to provide the audio on music’s biggest night!  I would also like to mention the big win by Shure endorsers Mumford & Sons for Album of the Year, fun. for Best New Artist and Song of the Year, and The Black Keys for Best Rock Song, Best Rock Album and Best Rock Performance.

So, things are kind of normal around here now, but I would be lying to you if I said I haven’t started thinking about next year!

Rock Out!
Cory

Contributors:

John Chevalier
Bill Gibson
Frank Gilbert
June Millington
Dan Murphy

“John had a semi-acoustic Gibson guitar.  It had a pickup on it so it could be amplified. We were just about to walk away and listen to a take when John leaned his guitar against the amp. He really should have turned the electric off.  It was only on a tiny bit and John just leaned it against the amp when it went ‘Nnnnnwahhhh!’  And we went, ‘What’s that? Voodoo?’. ‘No, it’s feedback.’  ‘Wow, it’s a great sound!’ George Martin was there so we said, ‘Can we have that on the record?’ It was a found object, an accident caused by leaning the guitar against the amp.”   

- Paul McCartney
(Source: Many Years From Now, Barry Mile)

It’s pretty much common knowledge among students of pop music that The Beatles’ 1964 recording of “I Feel Fine” was one of the first known examples of feedback as a recording effect, even though The Kinks and The Who reportedly (and intentionally) used it in live performances.   For most musicians and engineers, though, audio feedback is something to avoid.

In this post, we’ll cover some of the fundamentals – what causes feedback and how to avoid it – along with tips from some of our favorite audio pros.

What is acoustic feedback?
Acoustic feedback occurs when the amplified sound from any loudspeaker re-enters the sound system through any open microphone and is amplified again and again and again.  We’ve all heard it – it’s that sustained, ringing tone, varying from a low rumble to a piercing screech.

And what causes it?
The simplest PA system consists of a microphone, an amplifier and one or more speakers. Whenever you have those three components, you have the potential for feedback.  Feedback happens when the sound from the speakers makes it back into the microphone and is re-amplified and sent through the speakers again, like this:

Here’s an example: Let’s say that that you place the microphone in front of the speaker as shown here. If you tap the microphone, the sound of the tap goes through the amplifier, comes out the speaker and re-enters the mic.  This feedback loop happens so quickly that it creates its own frequency, and that produces the howling sound — an oscillation triggered by sound entering the microphone. Placing the microphone too close to the loudspeaker, too far from the sound source, or simply turning the microphone up too high all raise the likelihood of feedback problems.

Pro Tip #1: “The worst is vocalists who cup the mic capsule (e.g. rappers who put their hand around the grill of the mic because they think it looks cool). This invariably makes the mic sound horrible and very susceptible to feedback.  More importantly, it changes the directional nature of the microphone, changing it to essentially an omnidirectional microphone. One trick is to cut everything from 800 Hz to 2 kHz, compress it, and hopefully the horrible howling sound will go away and the vocals will still be intelligible. But don’t forget, the best thing to do to control feedback is turn everything down.”

- Frank Gilbert, FOH Engineer
Park West, The Vic Theater, and The Mayne Stage – all in Chicago

How to avoid it
Here are some suggestions on how to interrupt the feedback loop:
• Move the microphone closer to the desired sound source.
• Use a directional microphone to increase the amount of gain before feedback.
• Reduce the number of open microphones – turn off microphones that are not in use.
• Don’t boost tone controls indiscriminately.
• Try to keep microphones and loudspeakers as far away from each other as possible.
• Lower the speaker output. Move the loudspeaker farther away from the microphone. Each time this distance is doubled, the sound system output can be increased by 6dB.
• Move the loudspeaker closer to the listener. Each time this distance is halved, the sound system output will increase by 6dB.
• Use in-ear monitoring systems in place of floor monitors.
• Acoustically treat the room (if possible) to eliminate hard, reflective surfaces like glass, marble and wood.

Pro Tip #2: “In a well-designed system, the irritating high-pitched brand of feedback isn’t much of a problem unless someone points a mic into a monitor. So long as the performers are careful to always keep their mics pointed away from the monitors, or specifically to point that tail end of the mic at the monitor at all times, that shouldn’t be an issue.

- Bill Gibson, author of over 30 books, producer, performer and Berklee School of Music faculty member

When these solutions have been exhausted, the next step is to look toward equalizers and automatic feedback reducers.

A common technique used by sound engineers is “ringing out” a sound system by using a graphic equalizer to reduce the level of the frequencies that feedback:

1. Slowly bring up the system level until you begin to hear feedback. Now go to the equalizer and pull down the offending frequency roughly 3dB.
2. If the feedback is a “hoot” or “howl”, try cutting in the 250 to 500 Hz range. A “singing” tone may be around 1 kHz. “Whistles” and “screeches” tend to be above 2 kHz. Very rarely does feedback occur below 80 Hz or above 8 kHz. It takes practice to develop an ear for equalizing a sound system, so be patient.
3. After locating the first feedback frequency, begin turning up the system again until the next frequency begins ringing.
4. Repeat the above steps until the desired level is reached, but do not over-equalize. Keep in mind the equalizers can only provide a maximum level increase of 3 to 9 dB.

Pro Tip #3: “The last time I experienced feedback was in a small venue where I was onstage. As a musician and an audio tech, I’m a sound guy’s worst nightmare.  During rehearsal, my headset mic was feeding back and the audio tech kept turning my volume down and telling me that I couldn’t move around. I knew the problem was midrange feedback, so I explained to him that if he just lowered the midrange on the EQ, the problem would go away. He ‘passionately and firmly’ explained to me that the only way to get rid of feedback was for him to lower the volume and for me to stand still.

After enduring the first song, I walked back to the board, reached over his shoulder and dropped the midrange. I sang a couple notes, looked at him, smiled and walked back onstage. (Did I mention I was wireless, too?) The problem was solved and we didn’t talk after the set, but I know he learned something that night.”

- John Chevalier, pro audio/video expert, writer and speaker at InfoComm, NAB and other industry events

Pro Tip #4: “If there’s one thing I’ve learned in all my years of playing, it’s that the sound engineer has to be extraordinarily vigilant   even about protecting the performers’ hearing.

My last bad feedback incident was caused by gain stage being manipulated by the engineer without telling us – after we’d gotten to a good place.   The resulting, shrieking feedback changed everything – there was nothing but pain filling up space between our ears. Many people forget that EQ’ing something can cause a volume change – right in that frequency.

Of course, EQ can remedy volume problems quite easily. Just take a moment to ferret out the offending frequency or cluster of frequencies – band members protecting their ears, of course – and “forensically” attenuate, which will immediately solve the problem.  A hall of mirrors, isn’t it?”

- June Millington
FANNY frontwoman, musician and songwriter, co-founder of IMA

Automatic feedback reducers are very helpful in wireless microphone applications. Remember that microphone placement is crucial to eliminating feedback, and the temptation to wander away from the ideal microphone position when using a wireless is great. If the performer gets too close to a loudspeaker, feedback will result; a good feedback reducer will be able to catch and eliminate the feedback faster than a sound engineer.

And finally …

Pro Tip #5: “The best ‘gear’ a sound person has is his or her ears. Learn to identify the ringing frequency by doing blind ‘what is that frequency?’ tests using a sine wave generator or test tone generator. Have someone dial up a tone and see if you can identify what frequency it is. This is great training to identify the problem frequency during feedback howl and how I learned how to tame feedback.”

Dan Murphy, Sound Tech Director, Lakeside Church

NOTE: Don’t rely on an equalizer/feedback reducer alone to provide sufficient additional output in a sound system where the microphones and loudspeakers are too close together. You probably won’t get the results you need.  For more information about EQ, see this Shure Notes blog post.

KSM9HS (H for hypercardioid and S for subcardioid)

Back in 2005, Shure introduced the KSM9 vocal condenser microphone.  What made this microphone unique was its flip-of-a-switch ability to change from cardioid to supercardioid. Originally, a component in Shure’s premium UR24S/KSM9 wireless system, the mic found an enthusiastic audience that warranted its standalone status.

Live sound guys loved it.  Take John Mills, for instance: “This is a solid microphone with sound rivaling some of the best studio mics. If you’re serious about vocals, this is certainly a mic to try out. On second thought, just go get one and save some time and frustration with your vocal sounds.”

And Pro Audio Review said:  “This mic sounds like what you have always wanted a live mic to sound like. That is to say you have the brilliant clarity of a large diaphragm studio microphone in a durable live application. It is crisp without sounding too harsh, but warm and natural for a true reproduction of the human voice.”

The pros were on board and so were Erykah Badu, James Taylor, Buddy Guy and a bunch of other important people.  But back at Shure HQs, the engineers decided to take the KSM9 not only higher and higher, but lower, too. So back there, in Shure’s top secret Technology Annex, the question was, “What if the KSM9 came with switchable hypercardioid and subcardioid patterns?”

“What if …?” is here.  On October 26, 2012 Shure announced the KSM9HS vocal condenser microphone.  To get the Shure perspective (since all the reviews aren’t yet in), we went straight to Shure’s Soren Pedersen. He’s a Product Specialist and in true Shure Associate form, he’s also connected to the music business as a sometimes-recording engineer (rumor has it that one in five Shure Associates are weekend warriors of one stripe or another).  We asked him to tell us what’s so great about this mic.

This is a sibling of the KSM9 vocal condenser microphone.   How is the KSM9HS different?

The two share many design elements like the dual diaphragm cartridge, premium circuitry, and top notch shock mounting. The main difference is their polar pattern selections. Both mics offer two selectable polar patterns; the KSM9 switches cardioid and supercardioid, while the KSM9HS switches to subcardioid (also known as wide cardioid) and hypercardioid patterns.

That seems like a pretty nuanced difference.  What led to its development?

At Shure we’re on a never-ending quest for customer input. From talking to KSM9 users, we found out that there were a couple of features they wanted:

1) a mic with even less proximity effect, and

2) a mic with even more rejection for improved gain before feedback.

Working with our mic lab we found that we could create a version of the KSM9 with two new patterns providing a solution to both customer issues. The subcardioid pattern has greatly reduced proximity effect due to it being very close to an omnidirectional pattern, and the hypercardioid pattern has unbelievable side and off-axis rejection, even more than supercardioid. That helps to isolate the vocal and reduce the risk of feedback.

Has Shure ever produced a hypercardioid or a subcardioid mic?

This is Shure’s first handheld mic that features either of these patterns. We do have one hypercardioid headworn mic in our catalog (WCM16), which is a head worn mic also used for vocals.

Seems like most mics have a niche in either live sound or recording.  Where does this one fit?

Both KSM9 and KSM9HS were designed for stage use and live performances. But they’re also great studio vocal mics for artists who like to hold the mic while recording.

The original KSM9 has switchable polar patterns – from cardioid to supercardioid. But the KSM9HS is on both sides of that – from sub-cardioid to hypercardioid. Can you talk about the specific applications for the HS version?

With the grille removed, a flip of the switch changes the polar pattern.

The applications for the two patterns are quite different from each other, which makes the HS a more versatile vocal mic than most.

The hypercardioid side has amazing isolation and a big warm sound. You’ll really benefit from the off-axis rejection in especially loud environments where you may have stage monitors, guitar amps, or drums all pointing towards the mic which leads to a washy, unfocused vocal sound. On many hypercardioid mics, there’s a concern about too much proximity effect (the buildup of low frequencies as you get closer to the mic).

What’s unique about the KSM9 cartridge design is that it uses a dual diaphragm element. Having two diaphragms helps control proximity effect and results in a very smooth low-end response. Better than many other hypercardioid mics out there.

When switched to subcardioid (sometimes referred to as ‘wide cardioid’), it has more detail and will pick up more ambience, so it’s useful on stages with lower volume levels or if in-ear monitors are being used. Because subcardioids aren’t very vulnerable to the proximity effect, adding in the dual diaphragm to the equation means an exceptionally natural sounding low end. The wider pickup pattern is very “open” sounding and makes a great mic for interviews, Q&A, studio work or capturing multiple singers.

Around the halls of Shure, this is considered a ‘problem-solving’ mic. What are some of the problems it can solve?

The biggest problem it solves is related to feedback and bleed. Condensers are sensitive microphones that provide more detail than dynamic mics, but as the volume on stage goes up, the risk of feedback increases.

The KSM9HS set to hypercardioid has a tremendous amount of rejection so it can really help keep unwanted sounds out of the mic. For bands that use in-ear monitors, feedback is much less of an issue but the KSM9HS can still deliver a benefit.  The isolation it provides will reduce the pickup of unwanted sounds like drums and loud guitar amps and that results in a cleaner and overall better-sounding in-ear mix.

Ambience can be controlled using ambience mics instead of the band’s vocal mics so the engineer has better control on the in-ear mix.

There were undoubtedly some Beta tests out in the field.  Who was using them and what did they think?

That’s Kenny Chesney and the KSM9HS

Our Beta testers were absolutely thrilled with the mic. Some of the artists we tested with included Kenny Chesney, Cage the Elephant, Drive by Truckers, and Mastodon. Most of them having extremely loud stage volumes.  They were all fans of the KSM9, but they wanted more isolation. After evaluating the KSM9HS in hypercardioid, they noticed the improvement right away.

Kenny Chesney used it on his massive summer stadium tour and had some unique challenges that the KSM9 solved for his crew. He sings a song out in the crowd in front of a giant PA during the show and there weren’t any feedback issues at all because the KSM9HS rejects amazingly when set to hypercardioid. Kenny also likes to sing with his hand cupped around the mic, which can typically lead to big challenges in keeping a stable pattern and frequency response, but the KSM9HS is so directional that the response is very consistent regardless of the artist’s mic technique. The sound crew also used a KSM9HS set to subcardioid for guest vocal appearances.

Editor’s Note:  John Mills (yeah, the same John Mills who loved the KSM9 six years ago) was the Audio Systems Crew Chief for the 23-city Kenny Chesney/Tim McGraw “Brothers of the Sun” tour that Soren referred to. Mills said this: “One of the biggest problems with Kenny is finding a microphone that sounds consistent in any situation. You can cup it, then take your hand away, and the sound barely changes. It still sounds like a KSM9. And there’s also way less crowd noise coming in through the PA than there has ever been.”

It’s a condenser mic and it’s also two mics in one. How does it compare to the KSM9 in price?

The KSM9 and the KSM9HS are priced exactly the same ($699) and they are both available as wired mics or replacement wireless heads for use with Shure wireless transmitters.

Who should buy this mic?

Bands, artists, vocalists, and engineers looking to elevate their vocal mic both in sound quality, and pattern flexibility. If you have a loud stage, set it to hypercardioid, and if you like to “work the mic” at a coffee shop, set it to subcardioid.

For more information about the amazing KSM9HS, check out this video.

About SOREN PEDERSEN:

A member of the Product Management team at Shure, he attended Columbia College in Chicago, studying audio arts and acoustics.  Like many of his co-workers, he is a musician (drums and guitar) and still finds time to record local bands, using “all Shure mics, of course”. 

In its simplest definition: Equalization involves selectively boosting or cutting bands of frequencies to improve the performance of a sound reinforcement system.

Like many other audio technologies, EQ was born in telecommunications, where filters were used to restore and flatten all frequencies, so that response to all frequencies would be equal – hence the label “equalization”. Hollywood came on board in the early 1930s with the emergency of ‘talkies’, but it wasn’t until the late 1950s and early 1960s that Texas academics in the field of Physics did research that led to precursors of today’s pro audio technology. By the 1980s, graphic equalizers on our home stereo systems were the portals to EQ and many of us had a good time adjusting the sliders.

In the natural world, the sounds we hear are incredibly complex.  As we walk down a city street, we hear the rumble of a subway train, a police siren, the boom-boom-boom of an enhanced bass car stereo passing by or the voice of the person walking next to us.  But in a live sound or recording situation, none of us wants the listener to either cover his ears or struggle to pick out a specific sound source.

What equalization can do when used properly

• Noticeably, but not dramatically, improve the naturalness or intelligibility of a sound reinforcement system by emphasizing the frequency ranges most critical for speech.
• Noticeably, but not dramatically, increase the overall output level of a sound reinforcement system by reducing the system’s output in the frequency bands at which feedback occurs. These frequency bands will differ from system to system based on many variables, including room acoustics, microphone placement/design, loudspeaker location/design, even air temperature.

 Expert Tip #1

“When running live sound, I occasionally run into a feedback situation. When this happens, I quickly determine the frequency that’s feeding back, and by that I mean, ‘Is it high-end feedback? Mid-range feedback? Or low-end feedback?’ Once I’ve identified that, I turn down the appropriate knob on the EQ. It’s fast. It’s easy. And it works every time.”

- John Chevalier

What equalization can’t do

• Make a poorly designed sound reinforcement system work satisfactorily. Every sound reinforcement system is subject to the laws of physics.
• Improve intelligibility problems caused by reverberation, reflections, mechanical vibration, high background noise levels, or other problems caused by the location or physical design of the room. These problems are acoustical in nature and can’t be solved electronically. They must be resolved with acoustical solutions, such as sound absorbent panels and heavy drapes.
• Improve intelligibility problems caused by the talker being too far from the microphone.
• Improve the performance of sub-standard audio components in the sound reinforcement system.
• Eliminate distortion or noise problems caused by mismatched audio levels between system components.
• Improve echo return problems in teleconferencing systems.

How to approach equalization

FOH engineer and touring pro John Mills likes to think of each song as a line, with each instrument making up part of it.  If there are too many instruments or frequencies taking up the same space, the line gets bumpy and the mix gets muddy.

Expert Tip #2

Here are some general guidelines to consider when you’re trying to find your space.

20Hz to 80Hz: This is your sense of power in an instrument or mix.  It’s the stuff you feel more then hear.  The kick drum and bass guitar are down here in this range.

80Hz to 250Hz: The area where everything comes together.  This is where a lot of things can go wrong and too much in here will make a mix sound sloppy.

250Hz to 2kHz:  Most of your fundamental harmonics are in this range.  These are some of the most critical frequencies to building a solid mix.  Learn what instruments are most dominant in these frequencies and clean up around them.

2kHz to 5kHz:  Here you will find the clarity to almost everything.  But be careful, too much of a good thing can start to sound harsh.  This is an area where subtly is the key.

5kHz to 8kHz: Mostly sibilance and “s” sounds.  Much of the vocal consonants are defined in this range.

8kHz to 20kHz: Brilliance is the word here, the top end of cymbals.

“Becoming a master of EQ is like becoming a master painter.  Sometimes you just have to throw some paint on a canvas and see how it works.”

- John Mills

Approach equalization gently and slowly! After every adjustment, listen carefully to the resulting sound. The goal is to improve sound quality as well as increase the gain before feedback. When the system is loud enough and/or clear enough, stop equalizing! Also, stop equalizing and examine the complete sound reinforcement system in detail whenever the equalization causes degradation in the sound quality.

JOHN CHEVALIER is a pro audio/video expert, writer and speaker at InfoComm, NAB and other industry events.

JOHN MILLS is a touring FOH engineer and the expert behind the TechTraining101 site offering sound advice for engineers at all experience levels.

Contributors: Frank Gilbert, FOH Engineer at Chicago’s Mayne Stage, The Vic and Park West; Kent Morris, Peavey Electronics, Cornerstone Media; Stuart Rosenberg, Partner – SPACE and League of Creative Musicians

Live performance venues deal with it all the time.   In this post, we’ll break down the subject of acoustics for you into its most basic components, talk with a trio of our experts about how they handle venue challenges and offer some helpful hints that won’t require you to hire an acoustician.

A little history

The study of acoustics goes all the way back to the 6^th century, but the study of modern architectural acoustics is as recent as the 1900 when Wallace Clement Sabine designed Boston’s Symphony Hall according to scientific acoustic principles (based largely on reverberation time). Before then, the creation of great sounding concert halls was more a matter of luck than good design. Now concert hall acoustics is a recognized area of acoustics that straddles architecture, engineering and physics.  And Sabine must have done a pretty good job, since Symphony Hall is cited as the #2 concert hall in the world for acoustical quality. (Vienna’s Grosser Musikverinsaal is #1 and Carnegie Hall is #8.  London’s Albert Hall, which most of us know from “A Day in the Life” is ranked a distant #58.)

Acoustics By Definition

Acoustics is total effect of sound, especially as produced in an enclosed space. It’s the scientific study of the generation, transmission and reception of sound.  But here’s a simpler definition: It’s the total effect of sound in a room.

Audio expert Pat Brown explains how it relates to live sound reinforcement: “The sound heard in an auditorium by a listener is a complex combination of the sound produced by the gear and the way that it interacts with the room. It’s a fact that most of the sound heard by any listener gets there only after many, many interactions with the room’s surfaces. Each reflection modifies the sound a bit, and after several interactions, it looks nothing like what left the loudspeaker in the first place. The room places its own signature on all sounds radiated into it, which can either enhance or corrupt the sound. Good gear doesn’t sound good when used in a bad room”.

The fact is, there are no “good” or “bad” acoustics, only “appropriate” or “inappropriate” acoustics for the intended application.  Appropriate acoustics are those transmission and reception qualities in a room that enhance the musical performance and/or improve the ability of the listener to understand speech.  Music benefits from longer reverb time and constructive delay, so a room with those characteristics is considered “wet”.   On the other hand, speech reinforcement benefits from a “dry” room without the reflections that cause reverb.

So many advances have been made in the area of sound, that the bar for acoustical standards has been raised, along with the expectations of the audience.  No matter how great the performance is, it’s going to be a bad experience for the audience that can’t understand it.” 

Structural Concepts and Solutions: Isolation, Absorption and Diffusion

Isolation prevents sound from escaping its intended destination. By using dense door materials, tight seals, and double pane windows, transmission can be kept in check. Additionally, minimizing wall and ceiling penetrations will improve isolation.

Absorption uses a combination of dead air and mass to prevent the reflection of acoustic energy back into the occupied space. From mineral fiber to acoustic foam, different types of absorbers stop detrimental reflections that mask intelligibility.

Diffusion creates multiple small reflections from one or two large ones. The result is more pleasing to the ear, with an increased sense of “space” and “depth” as compared to a harsh two-dimensional slapback reflection. In a large space – where the slap and flutter from large parallel surfaces creates unpleasant sound –  diffusion, in the form of acoustical clouds and canopies, can rearrange the reflected energy into a usable soundscape.  

Example of acoustical clouds – Armstrong SOUNDSCAPES

With a careful study of the desired room signature, changes can be made to improve the overall sound in any room, whether the need is for isolation, absorption or diffusion.

We asked Kent Morris, President at Cornerstone Media and Worship Market Manager at Peavey Electronics, for some tips and tricks that you can use to improve room acoustics:

1. Divide and conquer. There is no rule that says the drums have to be placed at center stage. Move the drums to one side and place the singers and musicians on the other side. The physical separation will improve the clarity of each section and might increase gain before feedback in the vocal mics.

2. Baffle the sound. Build inexpensive sound baffles out of 2×4 wood frames and fill them with mineral fiber. Cover the sides with acoustic cloth and place the baffles (also called gobos) between the instrument amps and vocal mics to prevent sonic bleedthrough.

3. Aim high. Point the instrument amps at the people using them to decrease stage volume and prevent high levels from reaching the front rows.

4. Isolate the drummer. Use a panel behind the drummer to reduce rear reflections while improving the direct energy reaching the drum mics

5. Ditch the dish. In fan-shaped rooms, avoid aiming speakers directly at the rear wall. With a curved back wall, energy is reflected onto the stage, causing detrimental delays.

It can also happen that the solution is surprisingly simple and maybe even accidental.   A favorite venue of this Shure Notes editor is Space – a completely rehabbed and intimate music venue that has boasted the likes of Leon Russell, Taj Mahal, Dr. John and many others.  When we asked Stuart Rosenberg, the impresario behind the club, for an example of an acoustical problem and solution, here’s what he told us:

“When we built out our control room, we discovered that our design yielded significant resonance in the area of 30-100 Hz – a classic problem encountered in rectangular spaces, and potentially a vexing one that can prevent accurate low-end monitoring.  Much to our amazement and delight, we discovered that whenever we opened the door to the studio storage closet, the bass loading immediately disappeared – the volume of that space acted as an extremely efficient bass trap – and the frequency response of the room became linear. Problem solved!”

What a Sound Engineer Can Do

Let’s assume there’s nothing more you can do with the physical space.  Now what?  For another perspective, we turned to Frank Gilbert who is FOH and Monitor engineer at three popular music venues (once movie theaters and vaudeville houses) Park West, Mayne Stage and The Vic. We asked him to choose one and he talked about some of the challenges at The Mayne Stage.

Mayne Stage, formerly The Morse Theater circa 1912

“It’s a very deep room and I’ve noticed that unlike other places, when the room fills up with people, it doesn’t deaden up some of the bouncy low-mids.  We do drape the stage on all three sides with heavy-duty curtains and that helps a bit. At Mayne Stage, the FOH PA is a mono cluster with a pair of flown subs.  We do a lot of jazz trios., and with the upright bass, the flown subs start to rattle because they’re not coupling with any other speakers.

It’s a great sounding room with a great sounding system but with some of that deep stuff below 80 Hz, it shakes the HVAC in the room, so I just end up putting a high-pass filter on the upright bass and sometimes I even mute the subs and let the amplifier in the backline fill the room.   It’s such a live room that sometimes that’s enough, especially with those quieter shows.

With a rock show, you’ve already got a couple of guitar amps and a drum kit banging away, then your acoustic focus becomes getting the vocals to be heard. My favorite move in one of those situations is to use a Beta 58 instead of an SM58 – that always helps.   Sometimes in that room, a Beta is the right vocal mic.

We haven’t done anything in terms of acoustical treatments.  It would be really nice if we put curtains on the walls behind all the audience areas to deaden it up a little, but it’s actually a great-sounding room.  It’s well suited to piano jazz and cabaret but lately we’re doing more and more rock shows.   That room is about controlling bass and trying to control low-mids – bass management is really the name of the game there and when we have a full-on rock band, getting the vocals to sit well above the band is al little bit of a trick because there are no front fills at the lip of the stage – just the big cluster of speakers flown at the top of the room.  If it’s going to be a really loud band, sometimes I’ll take a couple of little speakers and put them at the lip of the stage, close to the audience.”

Frank Gilbert played in a band at age 15 and almost 25 years later, handles FOH sound at Chicago’s The Vic, Park West and The Mayne Stage.  He has a home studio and also does location recording for Metro Mobile Recording.

Kent Morris is the President of Cornerstone Media, worship market manager for Peavey Electronics, a speaker and a writer on pro audio topics.  He is a frequent contributor to Shure Notes.

Stuart Rosenberg is a musician, composer and producer. He is also the force behind SPACE, the Society for the Preservation of Art & Culture that brings live music and legendary musicians almost every night of the week to an intimate performance venue in Shure’s former hometown of Evanston, Illinois.

In our final Part 4 video, we discuss the myth that the SM58 is not supposed to have ‘proximity effect.’

Get up close and personal with an SM58, and the sound gets all warm and deep.  It’s called ‘proximity effect’.  In this video, Shure’s Chad Wiggins explains that this is perfectly normal – and how a savvy singer can use it creatively.

SM58 Facts vs Fiction Overview

• Part 1 – Myth: The SM58 is “old technology”
• Part 2 – Myth: The SM58 grille should never dent
• Part 3 – Myth: The SM58 causes feedback
• Part 4 – Myth: The SM58 is not supposed to have ‘proximity effect’

In part 3, we discuss the myth that the SM58 causes feedback.

When feedback strikes, the microphone usually takes the rap.  But feedback isn’t all the mic’s fault.  In this video, Chad Wiggins comes clean, and reveals that feedback is an acoustic conspiracy.

SM58 Facts vs Fiction Overview

• Part 1 – Myth: The SM58 is “old technology”
• Part 2 – Myth: The SM58 grille should never dent
• Part 3 – Myth: The SM58 causes feedback
• Part 4 – Myth: The SM58 is not supposed to have ‘proximity effect’

In Part 2, we discuss the myth that the SM58’s grille should never dent.

Like scars on a heavyweight prize fighter, a bashed and bruised grille reveals the long, hard road that an SM58 microphone has traveled.  Like a bodyguard, the grille’s job is to take a beating to protect the “VIP” – the more-delicate microphone transducer inside.  In this video, Chad Wiggins explains why a 58 keeps working long after other microphones have gone down for the count.

SM58 Facts vs Fiction Overview

• Part 1 – Myth: The SM58 is “old technology”
• Part 2 – Myth: The SM58 grille should never dent
• Part 3 – Myth: The SM58 causes feedback
• Part 4 – Myth: The SM58 is not supposed to have ‘proximity effect’

In Part I, we discuss the myth that the SM58 is “old technology”.

It’s true that the SM58 has been around longer than many bands.  But believe it or not, the technology that makes it work is still cutting-edge today!  In this video, Shure’s Chad Wiggins explains why other dynamic mic manufacturers work so hard at imitating the fabled 58 – and the one thing they all get wrong.

SM58 Facts vs Fiction Overview

• Part 1 – Myth: The SM58 is “old technology”
• Part 2 – Myth: The SM58 grille should never dent
• Part 3 – Myth: The SM58 causes feedback
• Part 4 – Myth: The SM58 is not supposed to have ‘proximity effect’