Most churches broadcast their worship services to some sort of mass media transport such as the Internet (video streaming), radio, TV channel, to other campuses, or they just record them for distribution later in audio CD, DVD, or Video-on-Demand (VOD). Unfortunately, not many churches have a good audio signal in their broadcast. The few that do have good audio are usually mega churches or other large churches that have invested a considerable amount of money into their audio chain. The ones that have trouble with their broadcast audio often simply lack knowledge. In this article, I want to share tips and techniques that help to set up, fix or improve most of the audio problems related to broadcast media.
A good audio signal is more important than a nice HD video signal. You cannot keep the attention of remote viewers on your broadcast or video streaming if the audio is poor, no matter how fantastic your video signal is, or how many camera transitions -- with all the bells and whistles -- you use during the broadcast.
What constitute good audio signal? A good audio signal is one without distracting noise or interference, It has a well-balanced mix of the instruments or music, and the spoken word can be easily heard and understood.
The most frequent problems found in broadcast audio can be divided into three main categories: noise or interference, mix balance, and distortion. Throughout this piece, I will cover each of these problems and provide suggestions on solutions.
In An Ideal World …
Ideally, all input channels from the stage (and any audio source from videos or files presented during the event) are shared by sending an exact copy of each input signal to different destinations. These destinations could be a monitor console, a broadcast truck, a recording mixer, the front-of-house (FOH) console, etc. This allows each destination to create an independent audio mix. There are two ways to split the signals: digitally or with an analog splitter. The analog splitter is basically a huge snake with one leg of the snake picking up the input signals from the stage and bringing them to the actual splitter, where the signal of each individual channel is divided into two, three, four, or more copies. This is done by means of a simple “Y-split” cable (yes, that simple) or a printed circuit board with branched signal tin conductors. One of the legs connects the inputs directly to the main console (usually the FOH). However, in the other legs, each split channel is electronically isolated from the others by passing its signal through a high-quality, high-input impedance audio transformer.
There are two important reasons for this: first, each of the split signals has the same level without any degradation in quality or signal strength and is free of noise that could be induced by any of the consoles connected to the splitter. Secondly, it also keeps the phantom power applied to the mics by the main console (usually the FOH or the monitor console) from reaching any of the other consoles. Some splitters have a ground lift switch in every channel to isolate the ground reference from the other split legs. There are also active splitters with sophisticated electronic circuitry.
Other splitters work in the digital domain, where the original signals from stage are converted to digital form and then copied and sent to different destinations in an audio digital network. The only problem with digital splitters is that only one console has absolute control over the analog preamp of the analog-to-digital converter. All the others can use a trim to adjust the received signal levels. However, digital splitters provide a consistent, high-quality signal to all consoles.
Having the ideal equipment setup for a professional live broadcast is not an option for most churches, since it can easily double the budget for audio alone. This is because in addition to the splitter, you need two consoles and basically two out-board processors in the case of an analog desk.
Why do we need separate audio mixes? This is the most important question when dealing with broadcast audio. Many tech volunteers don't realize that the FOH mix is not the ideal mix for broadcast, no matter how good it sounds within the church venue. This is because the FOH mix was constructed for the venue, which certainly is not a perfect or ideal acoustic environment. The ears of the person in charge of the FOH mix are receiving contributions directly from the stage’s instruments (sound coming directly from the guitar or bass amps, drums, etc., that is not necessarily coming from the PA), in addition to the PA sound. Also, the acoustic characteristics of the venue force the FOH engineer to EQ the channels to fit that acoustic environment. If you record such a mix directly from the FOH console and take it home, or listen to it in your car, you will note that it does not sound the way you heard it live. Most of the time, you do hear the bass or drums very far in the mix or simply not at all. This is completely normal because that mix was intended for a live performance in a particular environment.
In many places, the audio for the broadcast video is provided a feed from the FOH console. For the reason just discussed above, this is usually not the best mix for that purpose. Some people try to fix that problem by using the auxiliary outs from the FOH console to create a separate mix out. To some degree, this improves the audio mix send, however, it creates an enormous complication for the FOH tech -- because now the poor guy has to divide his mind into two or three separate mixes: the FOH, the various monitor mixes and, on top of that, the mix send to broadcast. This is like asking one person to manage three or four mixing consoles at the same time – not an easy task.
Ideally, the broadcast signal must be done in an acoustically isolated room, or in a room away from the main venue, and with its own set of monitors.
Broadcast Audio Made Simple
There are several ways to design and set up a professional-sounding broadcast mix using relatively simple and inexpensive equipment. I will discuss four ways or techniques to create a copy (or split) of your input channels. They are using direct outs; stem sub-mixing; using a simple Y-splitter; and, employing a digital split or networked digital audio.
Input Channel Direct Outs
Most medium- to large-format analog consoles have direct outs in each channel. Only a handful of small format analog consoles have direct outs in their input channels. These outputs carry a copy of the input signal using some point in the signal path within the channel strip for tapping. Depending on the console brand and model, different tapping points are used to pick up the direct out signal (post or pre preamp, post or pre filters, post or pre EQ, and post or pre fader). Since this tapping point varies from brand to brand and from model to model, you have to check out the console operator’s manual (e.g., input channel or block diagram) to be sure at what point the direct out signal is being tap from, and the different tapping options that it offers you.
The direct out is usually a ¼-inch jack -- sometimes a tip-ring-sleeve (TRS) balanced signal and sometimes a tip-sleeve (TS) unbalanced signal. This is an excellent alternative for the lack of a splitter snake. To use them for feeding a broadcast console, simply connect a snake with the corresponding ¼-inch plugs (again, check if your direct out jacks are TRS or TS) to the direct outs and feed the corresponding channels using the line or mic inputs. Now you are ready to start mixing the broadcast audio feed quasi-independently from the house mix. You can add any outboard equipment or processors you want to this console to create a mix better fitted for the broadcast purpose you need. This second console can be any kind of analog console, or even a small-format digital console, as long as it has the necessary channel count. Keep in mind that you could use the same exact broadcast mix for several purposes (e.g.,Iinternet streaming, recording, DVD, remote campuses, radio, TV, etc.). All you need is some sort of active distribution splitter for the final stereo or mono mix.
The down side of this method is that, depending on the signal routing design, the FOH console controls the preamp of each channel; changes in gain will affect the input signal level sent through the direct out. However, most church set ups are fixed set ups, where gain level changes are not necessarily changed too much once the worship rehearsal is complete. This can be easily overcome with some communication between the FOH and broadcast mix positions.
Stem Sub-Mix
The technique is quite similar to the previous set up; the difference is that the second console will be fed with pre-mixed stems containing several sections of the audio than can be grouped together. For example, one stem could contain just the vocals, another stem can have the drum set, others can have the keys, etc. These stems are created at the FOH console using the aux, group or matrix outs. This saves input channels at the second console since each stem is pre-mixed. For example, all vocals can be put in a mono or stereo out. Then, at the second console, it’s just a matter of mixing the stems to attain the proper balance between them. This simplifies the mixing at the second console. The second console can be a smaller desk in terms of input channels.
One limitation of this approach is that the FOH console needs to have as many auxiliary outs or matrixes as possible, since many of them may be needed for effects or stage monitoring depending on the particular needs. This approach is used quite regularly in big productions where a lot of input channels are coming from the stage, such as in the case of an orchestra or huge band where the various string, brass, percussion, or wind sections are premixed and then sent as separate stems to a master or broadcast console. Nevertheless, this technique can be easily implemented in a small church setting.
Y-Splitter
A Y-Splitter is the most simple and economic kind of splitter. It is simply and literally a cable where each of its conductors are split into two and then sent to two separate destinations. No active or passive components are involved here, just copper wires. Electronical engineers already took this into consideration when designing the output and input impedances of audio equipment, including mics and musical instruments. So, it is completely safe to split a signal with a Y-cable, such as from a mic, between two inputs without any significant loss of signal strength or degradation of audio quality.
A Y-Splitter can be constructed at home (or at church) using one XLR female connector for the input side and 2 XLR male connectors for the output side of the box. Instead of a face plate with the male XLR connectors, the output side could consist of two separate multicore cables (or snakes) each carrying the split channels to two separate consoles. Alternatively, you can find many stores (or online sites) that sell individual Y-Splitters in any combination of input and output connectors, or a complete multi-pair Y-Splitter in several channel counts.
When using this type of analog splitter, only one console should provide the phantom power for any source requiring it. This setup provides complete independence for each console since each will be able to control its preamps without affecting the other. Commercial Y-splitters can come with ground-lift switches for each channel (at an extra cost). If no ground-lift switches are available, make sure to have both consoles under the same electrical ground circuit. This will keep any ground-related noise from showing its ugly face in your mixes. (BTW, the stage audio equipment and instruments should also be connected to the same electrical ground circuit of the FOH and broadcast consoles, and should be separate from any other non-audio equipment, such as lights or fans.) Be aware that any unplugging/plugging of channel inputs or instruments directly connected to the splitter while running live will cause the noise to be propagated into the two consoles.
Digital Splitters or Networked Audio
This is one of the most advanced and, at the same time, simple ways to split or share the stage inputs among different consoles. Small-format digital audio consoles have evolved a great deal in the past few years. These consoles are increasingly easy to configure and are even easier in shareing audio input data. In addition to being easy to configure, another factor that simplifies a digital solution is that there is no need to deal with bundles of copper wires and multiple analog connections.
Many digital consoles provide some sort of digital audio output in the form of a general-use audio network protocol (such as USB, FireWire, MADI, or Dante), or as a proprietary protocol implemented as optional digital I/O cards (such as A-Net, REAC, ACE, Behringer UltraNet, HyperMac etc.). The problem with proprietary protocols is that virtually all of them are only compatible with equipment from that particular manufacturer. General-use protocols provide you more freedom at the time of expanding your configuration. One way to take advantage of these generic digital interfaces or protocols is by using a digital audio workstation (DAW) computer to record, and at the same time to perform a live down-mix that could be used for a broadcast audio feed. You can connect the USB or FireWire interface of your FOH console to a DAW computer. If the FOH console doesn’t have either, then chances are the manufacturer may offer a Dante-compatible interface card as an option. Dante offers a huge advantage over USB and FireWire. Dante is a distributed audio network protocol based on IEEE Ethernet standards and TCP/IP. So, it is fully compatible with regular computer network Ethernet switches from any brand or manufacturer. With this comes a number of additional advantages, such as longer distance, higher audio channel count, flexibility, and lower cost.
As an example (and skipping some minor configuration details), an FOH console equipped with a Dante-compatible interface could be connected to a regular Ethernet gigabit switch, using regular CAT5e network cable (UTP). To this switch you can connect a DAW computer using its network port (installing the corresponding Dante driver). The DAW will receive (via Dante) a copy of all the individual channels from the FOH console (up to 64 channels at 48K, or 32 at 96k, this may vary from one manufacturer to another). Moreover, you can configure this Dante network so that the gigabit switch will act as a digital splitter, sending a copy of all channels to all the Ethernet ports in the switch (multicast).This way you can connect any Dante-enabled equipment to the same switch and get all the channels. Note that each Ethernet cable (UTP Cat5e) connected to the gigabit switch can be up to 300 feet long. This will give you some serious freedom to put your equipment anywhere you need it. Please be aware that Dante is not compatible with wireless networks, wireless access points, or wireless routers. A similar setup could be done using MADI instead, however, the cable has to be coax or fiber optic and the connections can only be point-to-point (from one device to another). MADI is not compatible with Ethernet switches.
To illustrate the concept, I want to present two real world examples. The PreSonus StudioLive line of digital mixers is one of the rare small-format mixers that do have analog direct outs for each input channel. The direct outs, in this case, are in the form of DB25 female connectors, where each DB25 provides eight analog balanced direct outs. With the use of DB25-to-XLR (male) fan out adapters ($25 each, approximately) and a mic snake, we could feed a second analog or digital console to produce the broadcast mix. If you have a Behringer X32 (or any other model within the same family of digital mixers), most of them has one or two AES50 digital audio network ports in the rear panel. The Midas M32, M32R, and the Midas Pro Series also have AES50 ports in the back and at the stage I/O boxes. You can use one of these ports to feed a second Behringer digital mixer by using just one CAT5e cable connected to the AES50 port of the second console. This second console will receive a copy of all the channels, allowing you to create a separate broadcast mix with all the effects and processing available.
Keep in mind that these aren’t the only options; other brands such as Yamaha, Roland, Soundcraft, Allen & Heath ,and others offer optional interface cards for several network protocols, including MADI and Dante. The point is to sit down, get as much advice and information as possible, and then plan and design your configuration (preferably before making any purchase).
The Last Mile
Creating a great broadcast mix is important, but it’s not the only goal. The way this final mix is passed over to the encoder, recording device, or broadcast station, is also critical. Stereo mixes are much more superior to mono ones, so if you have the option, always strive for stereo. This last step in the broadcast audio production is very susceptible to noise or distortion if proper care is not taken when connecting the devices.
Signal Leveling (+4dBV, -10dBU)
Audio devices are divided into two main categories: professional audio level (+4dbu), and consumer audio level (-10dbV). This has nothing to do with the type of signal (unbalanced or balanced), it refers to the mean voltage level of the audio signal. Professional equipment is designed to manage signal levels that are hotter than the ones used for consumer devices. Professional signal levels are around three times (approximately) higher than the consumer-grade signals when considering the root-mean-squared value (RMS). Always make sure to use the appropriate signal levels in your input and output devices by matching +4 outputs levels with +4 level inputs and -10 level outs with -10 level inputs. Combining +4dbV and -10dbU devices either way could cause distortion problems on the device receiving the audio signal, or a noisy signal due to a degraded signal-to-noise ratio. Some devices can be switched between +4 or -10 levels of operation by means of an embedded button or switch in the equipment. If all you have is a +4 and -10 pair, then the best thing to do is to get a line level shifter or line level matching amplifier. This is a small device that looks like a direct box, but is designed to change a +4 signal into a -10 and/or vice versa. A standard direct box (DI) will not fix or match professional signal levels with consumer levels.
Balanced/Unbalanced Signals
This is one of the most common errors I see, and the one that is the source of the most noise and headaches. You cannot feed an unbalanced signal into a balanced audio input (or vice versa), unless you are using a direct box (DI) or you are using the correct type of cable specially wired for this purpose. Professional video switchers and encoders have XLR (or TRS) balanced audio inputs and they have no problem accepting a balanced audio signal from an audio mixer. The problem is that sometimes people try to use the RCA tape outs, or other unbalanced outs, and connect them into the balanced inputs of the receiving equipment without considering whether or not they are using the correct type of cable. Always consult the operator user’s manual to verify what type of input or outputs the equipment has (balanced/unbalanced, +4/-10, TRS/TS). Any RCA out is an unbalanced signal and also a -10dBU consumer level signal. Before feeding professional equipment with this signal, use a DI (on each channel of a stereo signal) to convert it to the proper format. In other situations, people try to feed the 1/8-inch line input jack of a computer audio card with a balanced audio signal from a console. The 1/8-inch line input jack of most computer sound cards (if not all) are unbalanced stereo TRS jacks. In other words, this input jack was designed to receive two channels of audio signal, each unbalanced, and each at -10dBU level. You can have great audio using a computer sound card as long as you use the correct format and signal levels. In this case, you need to convert each balanced signal (left and right channels) into an unbalanced one, and then use the level-matching transformer to level it to -10dBU. Finally, use the corresponding Y-cable to put the two signals into a 1/8-inch stereo or TRS plug.
Final Touches
For several important reasons, it is always good to insert a compressor/limiter right before the final destination of your broadcast mix. This prevents any peaks from overloading the encoder or computer audio input card, producing distortion. Also, the compressor will help in keeping a more stable loudness throughout your program audio. This is important because, by nature, our ears find it more pleasant to listen to sounds (for relatively long periods, like a worship service) that don’t have a wide variation in dynamic range. This is particularly important for the spoken word.
To complete the “icing on the cake”, add to your mix some ambient audio. Using a condenser mic (two preferably in stereo setup) can add an additional dimension to your broadcast mix. The ambient mic should be placed in a spot that can capture the audience’s reaction to what is happening during the worship service. The mics should point toward the audience and away from the main PA. These ambient mics should be connected to one (or two) channels in the broadcast console, not to the FOH console. When ambient mics are added to your mix, viewers feel like they are actually part of the experience -- they are “mentally transported” into the venue where the service is taking place.
My last bit of advice is to always plan ahead. Get as much information as possible beforehand, sit down and design your system before connecting any cables. With proper planning, you can implement your idea or goal in phases, until you get to the point you were dreaming of for your broadcast audio.
