And In This Corner…

In Uncategorizedby tfwm

So you have run out of inputs on your current sound system mix console and you are contemplating that next big purchase. Should you buy the latest digital model with enough screens, motorized faders and processing horsepower to satisfy the most hard-core techno-junkie or should you opt for the biggest analog desk with optional 64-channel sidecar and track mounted motorized mix chair to get to those end-of-the-console channels? To simply answer right now would require insights beyond my capacity and would require that I come up with something else to fill the rest of this space. So I will briefly set all jocularity aside (well, maybe just some), and delve into an exploration of features to help you determine whether an analog or digital console better fits your sound for worship requirements.

Not that long ago, we would not even be asking this question. Digital consoles, the few that existed, were expensive and designed mostly for the recording studio. There are many more choices today. But before we get to consoles, I would like to briefly look at the impact that digital processing has had on the audio industry and look at some of the “whys”.

CDs, DVDs, personal computers and MP3 players have completely changed how we listen to music. Although you still find those who love LP records, I do not miss the background noise, clicks and pops, limited low-frequency response and their bulky and fragile nature. Open reel and cassette tape machines have been replaced by digital recording technology as well. Digital audio workstations make editing and processing recordings far easier and reversible with nary a razor blade or grease pencil to be found. Adding auxiliary speakers to help cover a balcony, under balcony or overflow seating area before there was digital delay was a truly difficult proposition. The only options for effects were chambers, plates and springs.

If you look closely at the above examples you will find that the common element is the storage of audio. The transition to digital in the areas of recording, playback, signal processing and long distance signal transport was not without problems but is accepted in most applications today. Digital has brought us smaller size, potentially improved quality, and loss-less transport and duplication. Lower product and installation costs can result from combining processing functions like those found in digital loudspeaker management processors. But when you look at the mix console market today, analog products still hold a large share of the market. Let’s look at some of the reasons why.

Although there are many differences in features and operation, there is NOT a significant difference in the audio quality of good analog and digital mix consoles. In fact, it’s likely you could find persons to argue the advantages of either technology. Again, digital technology’s greatest impact on signal quality has been in recording, storage and the long distance transport of signals. So if there is not a big difference in signal quality in consoles, what are the differences? The main differences relate to features, signal-routing flexibility, the human interface for control, and how the hardware connects to the rest of the system.

The mix console is control central of any sound system. The inputs accept analog signals from microphones, instruments and playback sources allowing the mix engineer to blend these sources for presentation through the main and monitor sound systems. Digital console workings can be thought of in three sections; the control surface, the digital signal processing circuitry (DSP) and the input and output circuitry with analog to digital and digital to analog converters. In a digital mix system not all of these parts need be located in the same place.

Starting our comparison from the input, the microphone preamplifier is the first step in the chain. Because the preamplifiers in both consoles are analog, we will look at where the preamp is located and how its gain is controlled. Analog console preamplifiers are located in the console with the gain control in each channel strip. Digital consoles may have preamps located in the console but some have a digital link that allows them to be mounted nearby or on stage. Many digital consoles have an analog gain control located at the preamp (at the console or in the rack unit), but more expensive consoles have preamplifiers that are digitally controlled so that they can be adjusted from the console no matter where they are located.

Channel equalization is the mainstay of all consoles analog and digital. The EQ section of the console, which can range from simple to complex, allows the tonal characteristics of each source to be individually modified as needed. Channel EQ can range from simple shelving equalization with fixed mid-frequency control to full multi-band parametric equalization with a variable low-cut filter. Because the digital processing is the same for full parametric and simple fixed frequency equalization, you will often find parametric EQ in a digital console. The choice of EQ type is a trade off of flexibility and operational complexity.

So far the differences have been minor. In an analog console, adding processing to an input channel is done externally via the insert jack. Many digital consoles have insert jacks as well, but also may have internal signal processing. Compression or gating and de-essing are the most common signal processes applied to a channel and can do wonders for your final mix when properly adjusted. To get the most from these functions, make certain that the gain reduction meter is easy to see and the threshold control is easy to access.

We now arrive at the section of the console where the channel signal is routed to the master section. Analog consoles have three kinds of buses for channel routing; main, subgroups and auxiliaries. Auxiliaries are typically used for monitors and effects, subgroups are used for control and processing of a group of channels and the main outputs are typically used for the main sound system. Digital consoles typically have the same routing options but may allow you to convert the function of some of the buses to better suit your needs.

Moving to the master section, you can find full dynamic processing on the subgroups of some analog consoles and some digital consoles. Subgroups not only provide an easy way to control groups of channels but also allow processing to be applied to channel groups. Another valuable control feature found on some analog consoles is the VCA master control of input channel audio. In a standard console the channel fader directly controls the channel level. In a VCA console a Voltage Controlled Amplifier (VCA) adjusts the channel audio level via a control voltage from the channel fader and any VCA masters assigned to it. The important difference between VCA master control and subgroup mixing is the VCA controls the level of all post-fader auxiliary sends as well as the subgroup and mains. This not only keeps the reverb in balance, it is also important if you use an aux send for your subwoofers. Many better digital consoles have an equivalent function called DCA (Digitally Controlled Amplifier).

Digital consoles may also have additional signal processing in the master section to provide reverb and other effects. They may have equalization on their outputs as well. These features may be valuable tools or may simply be redundant if you use external processors.

The greatest difference between analog and digital consoles is the human interface. In an analog console, there is a control for every function on the console because each knob is actually connected to the circuitry making the change. The notable exceptions are VCAs and mute group control. However in a digital console, almost every control does nothing more than tell the console that you want to change something and by how much. Because the user control and audio adjustment are not directly connected, controls can serve a multitude of functions. The same knob used to adjust the low frequency EQ on one channel can adjust other inputs as well. In fact, the functions controlled can be completely different. This consolidation of controls can even go as far as we have seen in digital recording software, where the whole console could be controlled with a single knob or a mouse. One benefit of the consolidation of controls is a drastic reduction in the size of the console.

Here is the challenge. If we have fewer controls on the control surface than we have functions that are controlled, how does the user know what the knob does and the current position of the control? Motorized faders are part of the answer as they can move under computer control to represent the channel function to which it is assigned. Display screens and LED position indicators also help. A common control approach is to include knobs for one complete channel strip and then allow the user to select the channel to be adjusted. However with controls and faders that serve multiple channels, it must always be clear what function is currently being controlled. Analog console controls are arranged in columns with a user written label identifying the function of that channel, such as Pastor’s wireless, Pulpit, Electric Guitar etc. In a digital console with more inputs than faders there needs to be an equivalent label. In some consoles you still must write all of the input sources a fader controls on console label tape, but some digital consoles provide a small digital display for each channel to serve this purpose.

Another key feature of most digital consoles is their ability to store and recall snapshots of the console settings. The recall of all console settings can be a great benefit to churches that have different services or activities that require significant audio changes between those events. Recalling all console settings can greatly speed the transition. Although a full recall of all settings in not instantaneous, it is much faster than resetting controls by hand. However, if the console does not have digital control of the preamp gain and stored channel labels, you still have manual work to do.

The typical solution to this situation with analog consoles is to use a slightly larger console that provides additional channels for the alternative inputs. Programmable mute groups and VCA assignment can help greatly. This approach works as long as a wholesale change is not required. If everything changes, all you can do is take notes and reset as best you can. This is where snapshot recall can be particularly useful.

One last area of difference has to do with the interface to the outside world. Analog console inputs and outputs, not too surprisingly, are designed for analog signals. Most have extensive provision for connection of your favorite signal processors. Digital consoles have analog inputs but allow for direct connection of digital sources as well. Although digital snakes can be used with any analog console, some digital consoles will accept digital snake inputs directly.

So now that we have looked at some of the differences between analog and digital consoles you will probably find there are many things to consider when making a choice. The way the user interface works must be closely examined to determine how well the console fits your worship application. Analog consoles are still the benchmark used to evaluate the user interface on digital consoles. If you are considering a digital console, evaluate how quickly and easily you can get to and adjust the controls that you use the most. If you plan on storing and recalling snapshots, are all of the controls (including preamp gain) reset? As with any console, digital or analog, consider the features and functions not only in the context of your worship service requirements, but also in terms of how they relate to the skill of the volunteers and staff that will be using the console. Of course the cost must be considered as well.

No matter the technology you choose, you may want to consider a second small, easy to use console that can be used in place of a large complex console for simple applications. There may be occasions where requirements are simple and a second small console will allow your sound system to be operated by a much broader range of users.