Gain Structure Basics

Dave Rat explains gain structure on an analog console. Gain structure errors are some of the most common errors in church sound systems.

This is a video lesson. As usual, if you have difficulty with the video on your mobile device, click on the title ("Gain Structure Basics") or go to the CSG home page.

Controlling Drums in Church

Are your drums too loud?

By David McLain and Jeremy Carter Any time a band has some of its sound coming through the main PA system (usually vocals and electronic instruments) and some of the sound coming from the stage acoustically (most notably the drums) you have problems. The drummer must play loud enough to keep up with the sound system, which he cannot hear. However, playing loudly enough for the back row of listeners means that the drums are often too loud for the first several rows. It’s even louder on stage, which requires the rest of the band to play louder and turn up the stage monitors. The result is a stage volume that is overwhelming – too loud for the room, and often louder than the main sound system in the room, and still unclear. People get frustrated and irritable, and some leave to find another church where they can understand the music. A major part of the solution for this problem is to control the sound of the on-stage instruments, beginning with the drums. There are three steps in controlling drums in church: 1) Contain the acoustic energy from the drums, 2) Absorb the acoustic energy from the drums, and 3) Reinforce the sound that you want from the drums and provide monitoring back to the drummer. Containing the acoustic energy from the drums is the easiest part. The sound of the drums travels from the drum head to the ears of the people hearing it. The strongest part of that sound is generally direct line-of-sight.Many churches have installed plexiglass drum shields around the drums for this purpose. It’s cost-effective and it’s a reasonably effective starting point. The plexiglass reflects most sound, preventing the direct line-of-sight sound from reaching the people in the congregation. This solves one problem and introduces a couple of new ones. Plexiglass does not absorb sound; virtually all of the sound created by the drums is reflected; that means that the sound is still in the room, it’s just not traveling to the listeners in a direct route. The drummer often feels more confident now that he’s behind the plexiglass, and often times he plays harder, creating even more sound than before. Now that sound is bouncing around the room as reflected sound. Reflected sound is, by definition, noise: it has the same amount of energy as direct sound, but because it is reflected, it has become “incoherent.” Now instead of hearing the clear “slap” of the snare from a single source, we hear reflections of that slap from various reflective surfaces around the room. The clarity is decreased, but the energy of the snare is still there, rattling around the room, muddying up the rest of the sound. The second problem with a plexiglass drum cage is that the first reflection of the sound is concentrated back at the drummer’s ears. The potential for hearing damage is greatly increased. That’s one reason some drummers want to play loudly – they can’t hear the sound as well as they used to, so they feel the need to play louder. The result of plexiglass by itself is that the total energy of sound is not decreased. Instead, it’s just bouncing around the room, making the rest of the sound muddy, and damaging the drummer’s hearing. After we block the direct sound of the drums with a plexiglass drum shield, the next step is to absorb a good portion of the sound, to keep it from filling the room with incoherent echoes. This is generally accomplished with sound-absorptive foam. Generally, the foam is installed in three locations: on the wall behind the drummer, on the plexiglass itself, and as sound-absorptive “lid” over the top of the drummer. How much absorption to install is governed by several factors, some practical and some aesthetic. Since the drummer needs to be able to see the rest of the band, it’s best to not block all of the plexiglass. Rather, install foam along the bottom and sides of the plexiglass. Generally, the foam is not installed above the height of the drumheads themselves, and often only to the top of the kick drum. On the sides, install the foam higher, particularly on the side with the snare and hihat, as these are the greatest sources of sound. Install a greater amount of sound absorption on the wall behind the drummer. In fact, complete coverage of this wall is often appropriate, up to the height of the plexiglass drum shield. Since the sound from the drums is omnidirectional it will either strike the wall first or it will reflect off of the plexiglass and then strike the wall. Absorption on the wall behind the drummer will be a big help in keeping the reflections around the room under control. Some of the sound from the drums, of course, goes straight up, where it will bounce off of the ceiling before eventually making its way to peoples’ ears. If you have done an effective job of absorbing the sound inside the drum cage this reduced amount of reflected sound may be acceptable, or even desirable. It may still be too much sound, especially in a low-ceilinged room, or with a large drum kit, or with a particularly physical drummer. In this case, it may be necessary to add a sound absorptive ceiling over the top of the drum kit. All this absorption sounds expensive, but it is possible to cover all three sections - on the plexiglass, the wall behind the drummer, and the lid - for about the cost of the plexiglass drum shield itself. To this point, we have been reducing the overall volume of the drums. The stage volume is under control, so the musicians can hear themselves, and the sound from the stage doesn’t overwhelm the main speakers. The front several rows of the congregation are no longer being overwhelmed by sound. But now the back part of the sanctuary isn’t being reached. The third step of controlling the drum sound is to put the drums into the sound system. At the very least, you’ll need to mic the kick drum, the snare drum, and the hihat. With careful placement, a single mic can pick up both the snare and the hihat, for a two-mic minimum. As far as mic selection goes, my preference is to use a large diaphragm mic on the kick drum – either a dynamic mic like the Shure Beta 52 or the Sennheiser E602II, or a large condenser mic like the CAD E100. Dynamic mics tend to capture the “boom” of a kick drum well, and condensers can capture the “snap” of the sound. Audio Technica makes a mic (AE2500) that has both a condenser capsule and a dynamic capsule in it. Be sure that the mic can handle the high sound pressure levels of a kick drum closely miked. Your first choice for a snare mic is a simple dynamic microphone, with the ubiquitous Shure SM57 being the most popular. It’ll take a number of accidental whacks from overly-enthusiastic drumsticks and keep working well. Dynamic mics can also be used on the toms, but there are several very nice tiny condenser mics that have become popular, like the AKG C418 or the Audio Technica PRO 35. Sennheiser makes a small dynamic mic for this purpose, the E604. These small, specialized mics generally come with their own mic clips which attach directly to the drum itself, reducing the number of stands and cables sticking out of the drum kit, and allowing the plexiglass drum shield to be brought in nice and tight. In a large room, you’ll want to add a pair of overhead mics, to capture the overhead cymbals and the overall ambience of the drum kit. Small condenser mics like the entry level AT Pro37R or the higher priced Sennheiser E914 are common choices. Recently, the trend has been moving towards large-diaphragm mics overhead, including the inexpensive CAD GXL2200 or the versatile AKG C3000B. Be sure to experiment with mic placement, listening closely to the sound of each mic, to determine best placement on your drum kit. Once you route the new mics to your mixing console, you'll need to consider monitoring for the drummer. The simplest way to give your drummer the ability to hear what he needs to hear is to use an unused Auxiliary Send from your mixing console. Send that aux to a headphone amp (there are many entry-level manufacturers including Samson, Behringer, Rolls, and Carvin). Headphones with significant isolation help ensure the drummer will get the reinforced sound and not just bleed from around the ear muffs, and some drummers like headphones that emphasize low frequencies. In-Ear Monitor models which produce extended low frequencies (dual driver models) are also an option. Beyond this simple setup there are many other more advanced monitoring solutions such as a separate monitor console or personal mixing devices from folks like Aviom, Hear Technologies, Furman, and MyMix. If you have the room, I prefer using a compressor on both the kick drum and the snare, and an ideal world would call for gates on the toms, the snare and the hihat, to tighten up the sound, but most churches will stop before that point. The main goal is to prevent the acoustic sound of the drums from either overpowering the rest of the band, or reverberating around the room, by bringing the drums into the sound system with the rest of the band. You'll be surprised how much cleaner your band sounds, and how much easier it is to keep the volume under control. By David McLain and Jeremy Carter Originally posted on the CCI Solutions website.

New Battery Powered Portable PA

Samson came by the shop the other day, showing off a new battery powered speaker.

I never did get a photo of the front of this gadget: it's a plain, black steel grille with the Samson logo on it. It is a 40 watt, 6" two-way that sounds a LOT bigger than its size: I was really quite impressed with the audio, both in SPL and in frequency response. I'm told that with "normal" use (whatever "normal" is), you should get 10 hours of battery life out of this.

There are 4 channels of input:

• Channel 1 is a combo plug: XLR or TRS. Connect a Shure SM58 here.
• Channel 2 gives you a 1/4" TRS and a 1/8" (3.5mm) TRS. Connect your laptop or guitar here.
• Channel 3 has no connector: it's a wireless receiver. The wireless handheld is included! It's a single VHF frequency.
• Channel 4 is for the iPod connection on the top of the speaker. It's "fully Apple-compliant," which means that this knob controls the output of the iPod, and the jack charges your iPod while it's plugged in.
• There is a 1/4" jack labeled "Link". I didn't have a second unit to test with, but I'm told that using a TS cable (like a guitar cable), I can connect two units: any input into either unit is now in both boxes. Only two boxes can be connected.

There are "bass" and "treble" tone controls on the box, and they're set at frequencies that are musical: another plus.

If you have several boxes on the same wireless channel, you can transmit to all of them from a single microphone. One guy ran sound for a "walk-a-thon" at a local football field: he put one speaker on a speaker stand at each corner (they come with the socket built in), and transmitted to all four units at the same time.

I was really impressed with this box. When we have a group gathering at the park, I'll be bringing this along, plugging an iPod into the top, and letting it provide background music. When my church goes on missions trips, we'll be taking one or more of these (and we may not bring them back). I may get my wife one: she can plug her iPod into it when she's in the garden.

The price struck me as remarkably reasonable:

The unit as described: street price $399.99.

Without the wireless: street price: $319.99.

While this site is not about selling, if you'd like to buy one of these speakers (or a set) from the Church SoundGuy, send an email to churchsoundgear@gmail.com. The editor of ChurchSoundGuy is connected with CCI Solutions.

Checklist: Planning A Church Sound System

Answer these questions honestly to be off and running on your next church project.

by Peter Patrick

In every project there are always a number of driving factors. However, determining the importance of each is key.

Use this checklist to carefully assess your system needs and you’ll be well on your way to a successful church sound system project.

Priority of room purposes?
This is critical when room acoustics are considered.

Congregational singing benefits from strong room reflections, which naturally reinforce the singers voices. An acoustically “dead” space makes singing uncomfortable.

On the other hand, the strength of the reflections directly affects speech intelligibility in a negative way.

If the priority is the spoken word then room acoustics should be so weighted. A space designed for both requires some compromise and careful attention to the design of the speaker system.

Presentation styles?
Consider whether various styles of events such as plays, orations, bands, choirs etc are to be presented. Choirs require the use of long-range “choir mics”.

There is simply no way a choir can be amplified when located right beside a drum kit/bass guitar/rock band or any loud sound source without also amplifying the other sound as well. This produces a very poor mix of choir voices and backing instruments.

Communication needs?
Plays and musical shows require stage management and coordination by a stage manager who needs paging and announcement facilities in dressing rooms etc from a backstage location.

This can be managed on a budget through the main house mixers auxiliary send system or bus system in conjunction with a “Push To Talk” style mic for the stage manager, but the wiring needs to be in place first, rather than last.

More communication??
Following from the point above… IF pantomime style shows are contemplated please consider the need for headset comms between stage manager, sound and light controllers, stage hands (scene changes etc).

There are wired and wireless comm types available in a great range of capabilities. It is therefore worth working through your needs carefully.

Building shape/layout?
This is obviously a job for an architect. There is, however, great merit in getting a sound system consultant involved at the drawing board stage.

This work, along with that of an acoustical consultant, provides very valuable input to the process of simple things like whether choir mics will work or not. If you can locate a consultant with dual capabilities, so much the better.

Early budget by negotiation?
A PA system consultant should be able to give a fair idea of just what options are available at what approximate costs. Determine what you want your sound system to be capable of, and budget accordingly. Broad-brush figures should suffice early in the planning stage but be prepared to be flexible.

There are more than enough sad cases wherein too little money was allocated to this discipline in the first place and a second rate or simply inadequate outcome results.

This either means people have to live with a bad system or find another sum of money to retrofit new equipment. Retrofitting is always more expensive than getting it right the first time.

Installation process?
Consider whether you want to install the sound system yourself. For example, determine if there will be loudspeakers/equipment mounted overhead in public places. If so, do you have the skills and resources to ensure the mounting system meets engineering safety requirements?

Another example: are there skills and workforce power available to correctly connect the cables and test the sound system after completion to ensure all id’s functioning properly?

For some systems (where there are multiple speakers and possibly with digital delay requirements) this can involve specialized test equipment.

New or second hand?
Some items don’t suffer much with age and sensible use.

Buying a good quality mixing desk or amplifier second hand can often get you a much better unit than you would otherwise be able to afford.

Testing will usually reveal any problems and the risk of buying a bad unit minimized. Loudspeakers are not so easy to test and they do suffer mechanical stress. It pays to be extra careful in buying second-hand loudspeakers.

Music style?
Rock music usually demands higher sound levels, especially at the low end of the spectrum in amplified bass guitar and drum sounds. There is often an associated need for volume limiting to protect loudspeakers and equipment.

Range of instruments to be amplified?
A list of all instruments likely to be part of the show/service will help determine the system capabilities. An electric organ, for instance may create a need for special speakers capable of reproducing the bass pedal notes.

Style of amplification?
List all the different types of arrangements for getting the sound of the instrument into the sound system. Bugs on acoustic instruments, small microphones attached near the sound source,

Instrument mic on a boom? Note that every microphone contributes it’s own contribution towards feedback. The fewer microphones in use at one time, the cleaner the sound.

Number of inputs?
Please take care in accounting for all the sound sources/instruments that will need simultaneous amplification. Sound system components like mixing consoles loose value very quickly. Trading up to a larger unit can be expensive.

Room size?
This relates back to music style to some extent. Amplified drum sound in a small room is usually overkill. Low ceiling heights can cause real difficulties for even sound distribution sometimes requiring ceiling speakers to resolve the problem.

Vocal needs?
List all the different speaking and singing styles. For example, will there be a choir? Will there be need for a lectern mic or lapel mics?

Room layout?
The shape of the room and layout are extremely important to the business of avoiding feedback.

Orator mobility?
Is there a need for roving microphones? This has a strong effect on the type of equipment that will be suitable and the price and effectiveness of feedback elimination systems.

Wireless microphones?
Modern UHF wireless microphones are of two basic genres: fixed and frequency agile. The fixed frequency units are much lower cost but might not survive the introduction of a new TV station or translator to the area.

Will the whole system need to travel?
Relates to wireless microphones Fixed frequency units may not work at all if taken to another location.

What are the environmental requirements?
Noise pollution statutes can affect the design of a building to contain sound.

Special requirements will apply if you intend to use the auditorium for events requiring licensing permits, for example, multi-purpose assembly halls.

Ditto from your own perspective…
Nearby traffic noise, for instance, can be a real distraction.

What level of expertise does the average operator have?
System designers can make adjustments to cater to some extent for novice operators. Experienced, skilled operators, however, demand and make use of a wider range of facilities.

A high-power, complex system can serve to confuse novice operators and mitigate against the likely success of the system.

Is there a need for foldback?
Foldback loudspeakers allow vocalists to hear their own voice, instruments, etc. The use of loud foldback systems can be quite detrimental to the delivery of good sound in the listening space, however.

Placement of acoustic treatment at the rear of the dais can assist in controlling stray acoustical energy ("echo", “reverb”, and etc.)

What are the architectural restrictions?
The sound controller should ideally sit in a position which reflects an average of the sound in the listening area. Ideally, simply in the middle of the listeners. Because the whole audience hears the whole service through the sound engineers ears.

Light dimmers?
Whilst it is useful to co-locate light and sound control desks it is wise to maintain separation of audio and high power light dimmer cables.

Will there be multi core “snake” cables used?
Drawing snakes through ducts can be difficult. Consider your capabilities in removing the connectors, which, in a bunch, are usually too large to fit through a conduit.

Ducting size?
The use of audio “snake” cables is cost effective but the diameter of the cable is large - and arge radius bends are needed in ducts.

It is also better to put too many ducts into a concrete slab than risk under-doing the job.

Loudspeaker location?
Needs to be chosen carefully to plan not only for pre-cabling and audience coverage but also for ensuring adequate support structure is in place.

Loudspeaker cable routing?
The length of a speaker cable run is a determinant in wire size required. Long runs require larger diameter cables.

A proper design includes wire size calculations to maintain proper “damping factor” of the speaker to avoid excessive cone excursion.

Power distribution and nearby radio/TV?
The requirement for separate power cable feeds to different parts of a sound system can bring about a need for specially chosen “hum resistant” equipment and/or isolation devices and special cabling techniques in severe cases. Radio frequency interference (RFI) needs to be considered in the same vein.

Physical access?
Physical access to cabling and equipment is crucial to future serviceability, Try to ensure that ample removable panels are provided because every sound system needs updating sooner or later and all equipment made and installed by humans has a failure rate.

Ventilation?
Electronics (generally) and power amplifiers (especially) require generous air movement to maintain temperature stability. Try to ensure generous ventilation gaps are provided top and bottom of racks/cabinets to facilitate thermal air movement.

by Peter Patrick
from ProSoundWeb

used by permission

Survey: How Has The FCC Impacted Your Wireless Microphones?

The world of wireless microphones is changing. Any wireless using 700 Mhz is now illegal and subject to thousands of dollars in fines. But the FCC is not through with us: the White Spaces issue is likely to threaten us further.

How much has the FCC impacted your organization's use of wireless microphones? How much will they affect you with the next transition? Please take a minute to give us your opinion.



If you have received this as an email, please click on the title to fill out the survey.

Any questions or comments? churchsoundguy@gmail.com.

Studio Live: "My First Digital Mixer"

I really should have put this up some time ago. It has been a long time since a new audio mixing board has generated as much hubbub and interest as the PreSonus Studio Live boards have. And in a significant departure from previous "exciting new" consoles, these boards are actually affordable! Imagine that!

Their first board has already become an industry standard as a transition console from the analog world to "my first digital mixer". Many churches and touring groups are choosing the Studio Live board because they want the power, the audio quality, and the recall-ability of a digital board at the price of a small analog board; users particularly love the concept of a digital board that is as easy to use as an analog board! They've been delighted to learn that with a single cable, you can quickly and simply record up to 16 channels of digital audio on a computer, either Mac or PC; the raft of on-board compressors and effects just sweeten the deal (and save $$ on outboard gear)!

That original board was the 16.4.2, is a 16 channel board, and we sold many of our first few shipments of the 16.4.2 as standalone, 16-channel mixers. Gradually, people became aware of the fact that two of the boards could be slaved together to make a 32 channel board. An interesting thing happened: first, most sales were now for two of the boards, not for singles, and second, many of the folks that had bought a single board called back for a second one.

(The connection of two boards is remarkably simple: a FireWire cable connects the two boards. If you like, there is a gadget to physically attach them together to make one physical console as well.)

But the transition from analog to digital hasn't been without some challenges. A fair number of dyed-in-the-wool analog guys have had difficulty wrapping their mind around a digital board. More commonly, I get questions from users of earlier digital boards made by pioneers in the digital mixer world: they are afraid that the Studio Live boards will be as difficult to use as those boards.

And it was with these two scenarios in mind that my friend (and president of the sound company where I work) made this video to introduce the Studio Live board, not from a sales perspective, but from an audio engineer's perspective. Listen while Ron walks us through the Studio Live console:

More recently, PreSonus has introduced the big brother to the Studio Live 16.4.2, the 24 channel 24.4.2. It's not just "8 more channels" (though it is that), they've added quite a number of new features, and now people are having trouble deciding: do I choose the 24 channel board, or do I slave two 16's together to make a 32 channel board. And now two of the 24's can be slaved together to make a 48 channel mixer (though there are some recording limitations due to the 32 channel capacity of FireWire), so churches are beginning to buy this board in pairs and slaving them as well.

This is Rick Naqvi of Presonus introducing the 24 channel Studio Live 24.4.2 digital mixer. He really understands the board well (he should; he works for PreSonus), and can point out the difference between the boards.

If you're interested in one (or two) of either of these boards, give me a call (800/426-8664) or an email (churchsoundguy(at)gmail.com): we have "Try it Free" units for you to test, and we have the boards in stock, each with a "satisfaction guaranteed" warranty in addition to PreSonus's product warranty. Or call if you just want to talk about your sound system hopes and dreams.

Compression in the Live World

In the good old days of “making records,” compression was mostly used as an envelope modification tool. But around the beginning of “the great loudness wars,” some famous studio mixer dudes found they could get more work done in a shorter period of time by removing all the dynamics from the music, then equalizing it into place in the sonic arrangement.

Seeing as many of these dudes are charging several thousand dollars per song, and don’t really care how the final product hits the street as long as they can wail through a couple/three songs a day, it’s a great idea. Unless you happen to like music.

Unfortunately, the actual product – a hyper-compressed, no-dynamics ball of ick – is now viewed as normal for the presentation of music. The real irony is that this all started with the advent of the compact disc, which was heralded as the Next Great Thing due to it’s extended dynamic range.

So here we are in 2k5 with racks and racks of “studio quality” compressors traveling with so many live shows. Lately I’ve also been in clubs that had more Empirical Labs “distressors” than many studios.

The original problem with “live” compression was that it “sucked up” the stage sound between songs, which often caused feedback. But with the proliferation of “personal monitor” rigs, this is no longer the case. So squashing the heck out of the music has become perfectly acceptable.

Now, in addition to compressing the bass, in addition to compressing the drum sub, in addition to the studio trick of using parallel compression on the drum sub, in addition to compressing the vocals, the backing vocals and a maxi sub mix of all the vocals, I’ve seen more and more of the brothers compressing the “2 Mix” bus.

Why do I care? Because many of my live sound brethren employing this technique have been doing it in such a terribly inappropriate manner, and with such ineffective tools.

I know, I know – you’re just trying to get the show as “loud” as possible while living within the 98 dB (A-weighed; 105 dB C-weighted) SPL ceiling imposed by the local constable who just loves to hang at the FOH position with his little un-calibrated “Rat Shack” meter.

The harm, at least from my perspective, is that this often does not properly serve the artist, because the dynamics of the music are directly linked to the emotion of the performance.

There are some compression units that excel at allowing the emotion of the performance to creep through the reduction of dynamic range, and there are units that should never be used in this application.

Generally, if a compressor has a low-cut filter prior to the detector circuit (this keeps low-frequency energy from driving the gain reduction), it’s probably a suitable unit. If there is one set of controls governing both sides of the unit (true stereo versus linked dual mono), then it very well may be an appropriate unit to strap across a mix bus.

It has nothing to do with “toob” versus “squalid state” – there are great 2 Mix compressors that apply to either (and sometimes both) technologies. It has more to do with the internal headroom and overall frequency response of the unit (DC to light is about right). This, along with the ability of the unit’s gain reduction cell to control the dynamics of the presentation without pumping, wheezing, begging for mercy, nor removing the intensity and emotion.

During production rehearsals, simply listen to the mix with the compression engaged, and then disengaged, while making a concerted effort to knock down the dynamics of the presentation as seamlessly as possible.

When the pumping and wheezing ceases, you’re on the right track.

from Live Sound International. Used by permission.

___________________________________________
David McLain | The Compressor Guy | CCI SOLUTIONS
Be seen. Be heard.
PO Box 481 / 1247 85th Ave SE
Olympia, WA 98507-0481
Voice: 800/426-8664 x255 / Fax: 800/399-8273
email: dmclain@ccisolutions.com
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