SPS Blogpost #4 - Ten Reasons Why Church Sound Systems Cost More

Churches can be vastly different from any other kind of large venue used for music and speech.  It is often said that installing a professional audio system within a church can be much more expensive than other venues, and this article by Pat Brown addresses the most common reasons as to why that is often true.

Reason 1: Dynamic Range
     Because churches are noticeably quieter than other typical venues, the sound system must be able to prevent audible background noise within the audience while being as quiet as possible.  This requires a dynamic range that would most often be found in recording studios and other spaces that are used for critical listening.  Pat Brown states that 96 dB would meet that criteria.  It is important to use proper gain structure to eliminate as much background noise as possible.

Reason 2: Energy Ratios
     Every seat within the church must have optimized for appropriate signal-to-noise ratio and early-to-late energy ratios.  It is important that the seating in the church are located within the spaces' sweet spot rather than a null.

Reason 3: Uniform Coverage
     Different loudspeaker setups cause different interactions between the loudspeakers and greatly affect their coverage, causing the room to have certain hot and cold spots where the sound can be optimal or not so great, respectively.  Having great coverage and great sound at every seat in the room requires a good loudspeaker setup, and its as simple as that.

Reason 4: Versatility
     Developing a system that is specialized for both music and speech is much more difficult of a task than developing one for just music or speech, being that these two types of presentation require different attributes.  Having your system be optimized for both is going to cost a pretty penny.

Reason 5: Hum and Buzz
     Improper grounding practices within the installation of the equipment or wiring of equipment can often result in buzz and hum within a system, something that is very bad for a church congregation.  This can be eliminated by modifying some equipment to work without hum and by proper grounding and shielding of wiring and equipment.

Reason 6: Gain-Before-Feedback
     multiple mics and long distance micing are two necessities for a church service, but are unfortunately two big potencial causes for feedback.  The only way to prevent feedback or at the very least, reduce the potential for feedback as much as possible is proper placement of both the loudspeakers and the microphones as well as proper training of the staff and making sure they know the limitations of the system.

Reason 7: Wireless Microphones and radio frequency interference (RFI)
     devices must be properly shielded and filtering devices must be installed in order to eliminate interference from frequencies above the audible band.  Wireless mics are a great tool within the operation of a church service, but its important to use wireless frequencies correctly in order to prevent RFI.

Reason 8: "Clean" Installation Practices
     Proper installation of the system plays an integral part in the overall success in the system.  Following all installation codes and being able to keep the visual aesthetics of the installation site intact without having the installation affect it greatly is very important.  Without proper installation, there is no proper operation.

Reason 9: Professional Equipment 
     This one can really make a dent on the wallet, but it is worth the investment.  Having the best and most-suitable equipment possible and ones the meet all fire and safety codes can make the difference between making repairs to a system and replacing the system entirely.  

Reason 10: Calibration, Training and Documentation
     though a significant amount of expertise and a certain amount of advanced audio and acoustic equipment is required to make a system as "user-friendly" as possible, a properly calibrated system is easier for personnel to operate (Brown 3).  It is also important that the churches personnel be properly trained and educated with the use of equipment manuals to ensure that services run as smoothly as possible.


Works Cited
Brown, Pat. "Ten Reasons Why Church Sound Systems Cost More." ProSoundWeb. 03 Oct 2011: 3. Web. 31 Jan. 2013. <http://www.prosoundweb.com/article/ten_reasons_why_church_sound_systems_cost_more>.

SPS Blog Post #3 - Portable Power: The Secret Life Of Generators

I am very happy to have found this article.  It is people like me, those who are not the most knowledgable about power and electricity besides safety, who this article is gear directly towards.  If someone were to ask me what a generator is before reading this article, I would have explained how it was a machine that runs on gas and creates electricity, which is possibly the most vague answer ever.  As someone who eventually

A much more thorough answer is that "a generator is a machine that converts rotating mechanical energy into electricity (Leerman 2)."  While generators con often vary in size and shape they all consist of the same 4 essential parts: the engine, the generating unit, the governor controls and the distribution.

The engine within a generator spins what is called a rotar inside a series of windings called the stator.  As the rotar moves within the stator, electricity is generated (Leerman 2).  The governor controls are what maintains the generator operating efficiently by controlling the load and maintaining the proper engine speed.  The distribution section, like a power disconnect, allows us to tap into the power through the use of lugs and connecters, while also containing all of the circuit breakers in case of an overload (Leerman 2).

Standard generators, those that would be found powering a construction site and similar environment, are loud and are often not as stable as we need them to be, often being unstable by 25 percent.   The generators we require need to be able to power very sensitive electrical equipment at a stable and constant voltage and frequency and generate as little noise as possible for us to be able to have more placement options.  When searching for the right generator, look for types with the words 'quiet', 'production', or 'show' (Leerman 2).

It is also very important to know how much power the show or production you are working on will require.  It is much safer to select a generator that is able to more power than you may necessarily need because you never know when you might need to make a last second addition that needs power.  Not being able to meet the power requirement will negatively impact the production.

Knowing and being familiar with the National Electrical Code, or NEC, will help prevent any unexpected issues with operating a generator or any other electrical system.  Many of the have adopted the safety guidelines outlined within the NEC as law, so that would be another incentive to read up on your power and electrical safety codes.

Works Cited
Leerman, Craig. "Portable Power: The Secret Life Of Generators." ProSoundWeb. 03 Dec 2012: 2. Web. 24 Jan. 2013. <http://www.prosoundweb.com/article/portable_power_the_secret_life_of_generators/live/>.

SPS Blog Post #2 - Proper Loudspeaker Placement: How To Avoid Lobes and Nulls

In an effort to almost continue what I was talking about last week,  I have opted to further research how to properly set up a loudspeaker array for the maximum amount of even coverage as well as reducing phase issues and as much as possible.  For this, It is necessary to know how to reduce the amount of lobes and nulls within a loudspeaker system.

The word lobe, when used in the context of audio, is often defined as a maximum of sound pressure that occurs within a sound field caused by the loudspeaker array.  The author of the article, Pat Brown, describes them as "'fingers' of sound pressure 'maximums' in the three-dimensional space..."(Brown 3)  Lobes can be problematic as most microphones set within a lobe will almost undoubtedly feedback.  Nulls, on the other hand are the exact opposite.  Nulls could be thought of as sound pressure minimums within a speaker array, which can cause a lose of speech intelligibility within the audience.

As Pat Brown has detailed in the article, There are many possible "solutions" one can take to combat these problems, such as comb filtering, with some being much better ideas than others.  One could use an analyzer resolution to reduce the comb filtering and adjust the equalizer.  Though this may seem like a quick fix, them problem has been temporarily masked and has not truly been fixed.  Another option would be to notch out certain problem frequencies, although this could be detrimental to the sound quality because you are removing necessary frequencies.  One could simply be to conclude that the audience won't even notice the filtering and do nothing, but that truly doesn't solve anything.  The only real way to solve the problem is to address the spacing of the loudspeaker array.

Comb filtering and phasing is a timing issue, so by spacing two loudspeakers that are close together further apart, the amount of lobes and nulls created will be reduced.

Take note that it is also possible to reduce these lobes and nulls by using quality loudspeakers.  Some loudspeakers are built to have features, such as horn-loaded components and aggressive pattern control, that help reduce interaction with other loudspeakers, which will reduce a lot of comb filtering and phasing issues.  Though larger speakers seem to be better, if size is an issue in a particular venue, one can use smaller speakers in greater number set up closer to the audience, such as an exploded array (Brown 3).

To fully understand this, I had to further research what an exploded array is.  Though I wasn't able to find an exact definition of explanation  from many images I could find I gather that it involves separating the components in a loudspeaker from each other so that the highs and the mids are not coming from the same speaker enclosure.

Works Cited

Brown, Pat. "Proper Loudspeaker Placement: How To Avoid Lobes and Nulls." ProSoundWeb. 13   Jun 2012: 3. Web. 17 Jan. 2013. <http://www.prosoundweb.com/article/lobes_and_nulls/>.

SPS Blog Post #1 - Optimizing The Low End: Run & Gun Subwoofer Arraying Techniques

First off, I would simply like to state that this was one of the most informative and easily comprehendible articles pertaining to this issue I have read.  Bennett Prescott really knows his stuff but also has a way of explaining sometimes complex concepts in an easy to understand way.

Now to the nitty gritty.  This topic has been one that has always intrigued me.  Low end sound is crucial to any mix and getting it to sound its absolute best is often difficult and tedious.  Luckily Bennett Prescott was kind enough to list off a few techniques and information that can help every system tech have their low end sounding its very best.

Prescott shows how a "small sound source", being an acoustic sound source where no dimension of the source is larger than one-quarter wavelength at the frequency of interest, demonstrates near perfect omnidirectional response in the free field he is testing.  But when one subwoofer is set up next other subwoofers, the omnidirectional response demonstrated by the single sub has now been altered and begins to demonstrate what is called pattern narrowing, which occurs due to phasing.  Prescott defines phase as, "the offset between two waves, measured in degrees".    When two waves are perfectly in phase with one another, meaning a difference of 0 degrees, there is a boost in gain of 6 dB.  However, two wave out of phase by 180 degrees will cancel each other out perfectly.  Any other kind of phase relation will contribute anywhere between 6 dB gain or wave cancellation.  Any sound sources outputting waves that are between 120 to 180 degrees out of phase with each other will begin resulting in sound reduction, which is what we as system techs do not want.

From there, Prescott demonstrates different arrays of subwoofers and the effects each one has on the sound they output by diagramming the noise boosting and canceling caused by phasing.  Some of the most intriguing diagrams were the ones demonstrating a left and right stereo array causing what is called a "Power alley", where the sound from both subwoofers arrives at the center of where an audience would be located and would be boosted in gain, where as about a third of the sound that would reach the audience, roughly the far left and far right of the audience, is reduced or cancelled out.

 The effects that physical and/or digital delay have on subwoofer arrays was very eye opening, in that simply moving one or two subwoofers a foot behind the others can have a dramatic effect on the way the sound is heard within the audience.  I never thought about how a physical delay focuses sound back onto the stage while a digital delay affects the sound on both sides of the array equally.

One of the best tidbits of information I gained from this article is the mixing of both center subwoofer arrays and stereo loudspeakers to create the most even sound coverage possible. Prescott states that he uses the technique of using a left right center sub array in tandem with the stereo loudspeakers most often than any other, which is something I'll take with me and try applying when and where I can.