Gear Talk: Audio Distribution Part 1

These days more and more churches are growing their audio setups.  Some, want to do broadcasting to an online audience, others want to grow their worship team by adding a monitor consoles, while others may want to send all or parts of their mix to another space, still others may want to do all of the above.  This leads us into the wide world of audio distribution. In the upcoming series we will take a look at all the different forms of audio distribution from digital to analog and what their abilities and drawbacks are. For this first week, we’ll primarily stick to analog as it will build the foundation for the digital formats to follow.  As we have touched on in the How to Mix for Broadcast series, audio splits can be very useful and come in both analog and digital flavors.  This new series on audio distribution will cover both the analog and digital variants. We will also cover the various pros and cons of each type and of the special needs of some of the digital distribution methods.

Before we dive into the wide world of digital audio formats, it’s important to understand the analog variants many digital audio formats are modeled after.  The world of analog audio distribution is just as varied as digital distribution. Just like digital audio, there are a bunch of different formats that carry analog audio in different ways.  Analog audio distribution is done with splitters. While there are many kinds of splitters, the simplest is just a Y-cable. In fact, all big splitters are basically just multi-channel Y-cables.  Some have extra features and some splitters split more than just two ways, but all analog splitters, at their heart are just simple Y cables. Analog splits come in many formats and channel counts.  A simple 1:2 all the way up to 64:3 are common. Some of the more common formats of split are transformer isolated and groundliftable. Transformer isolated splits are the preferred method for large format splitters.  They work by splitting the audio 2-3 ways. One output is a direct Y cable split. The other output or two outputs are wound around a transformer in a 1 to 1 ratio to remove any DC voltage. This makes the transformer isolated outputs much less susceptible to any interference but has the effect of also isolating the outputs from phantom power.  This is mostly a protective measure to ensure that multiple consoles aren’t sending phantom power at once which could damage some older phantom powered microphones. The remedy for this when using a transformer isolated split is to make sure the console connected to the main output is able to phantom power any and all channels needed on the split.  Professionals have used splitters to allow any console using the splitter to their own gain settings instead of having to share and digitally trim (there were issues with doing this in the early days).

Another area of the analog realm that carries over into the digital arena is patch panels.  Analog patch panels are a really useful tool in live sound. You won’t typically find patch panels on tour setups but they’re still very ubiquitous in venues, even venues with digital consoles.  Patch panels are also still heavily in use in the broadcast world because of the flexibility they provide. Most audio patch panels in use today use the TT connector. It’s kind of a cross between a 1/4in cable and a mini cable and is a leftover of the old analog phone days.  TT actually stands for TinyTelephone and was primarily used by AT&T phone switchboards. However it is a fully balanced connection and is nice because its so small you can fit a lot more connectors into a block of TT patch panels than if you used XLR or even 1/4in connectors.  Like splitters, not all patch panels are created equal and different patch panels have different abilities. Patchbays can come in three variants. Normal, half normal, and non-normal. All of these have different characteristics that make them useful in certain situations. Normal patch bays are setup to work when nothing is plugged into the top or bottom.  They are wired so that whatever is plugged into the top port, flows to the bottom port. Plugging something into the top will break the connection and route the audio away from where it was originally flowing. Half normal patch bays work similarly except that when you plug something into the top port, it splits it and will continue to flow to the bottom unless you plug something else into the bottom port.  It is essentially a Y splitter. Non normal patch bays NEED you to connect the top and bottom ports to work. These are typically used in spaces that have much more physical I/O than console channels. The user can decide what goes where for each use. All of these options have their uses in certain cases and are a great option depending on your needs.

One more area of the analog world that I would like to touch on is snake connectors.  There are a lot of different analog snake connectors floating around these days but I’d like to touch on some of the more popular ones in use today.  One connector that sees a lot of use in studios more so than live environments is the DB25 connector. This looks loosley like the letter D and has 25 pins.  This allows for 8 channels of audio to pass through it. The DB25 connector is often seen on the back of patch panels, on a lot of recording gear, on the back of some Digital I/O modules where space is tight.  Be careful as there are a couple different pin-outs. The main two are TASCAM and YAMAHA pin-outs. It’s still 8 channels of audio but the two versions have differences on what pin is ground. Another connector is the CPC connector.  This is a circular connector that houses at least 8 but potentially 56 or more channels. CPC connectors are ubiquitous all over the place on tours, in theaters, and Houses of Worship (HOW) and are very useful. CPC snakes are a little scary because there is no one correct pin-out for them so you have to be a little careful when fixing one or changing one.  CPC snakes are cool because the CPC format can be made to fit just about any need and when paired with a patch panel, it can be extremely flexible. The last of the analog snake connector types is DT12. DT12 is a standard that carries 12 channels of audio in a round connector similar to the CPC format. What’s nice about DT12 is it conforms to one standard pin-out and has a VERY rugged connector.  DT12 is primarily used by OB (Outside Broadcast) trucks and other broadcast applications. It’s great for its size and weather proofing. While there are a ton of other snake connectors, these are the main players on the market today.

One last analog snake format that has become VERY popular in the past couple of years and can be very useful in spaces where there is a lot of cat5e but not a lot of traditional copper, is the analog audio over ethernet snake.  Analog over ethernet snakes utilize the 8 twisted pair cables inside a shielded cat5 cable to run 4 channels of audio with a shared ground over the shield. These can be extremely useful in situations where there is more cat5 than traditional copper.  A lot of companies make many versions of these. Some make boxes you can attach on either end of the cable, others make pigtail versions, a couple companies even make wall boxes. Most of them allow you to daisy chain snakes so you can multiply your four channels down the line.  Whirlwind, RatSound, Radial, and ProCo all make these.  Most of these manufacturers make DMX versions as well.  One thing to note is that a shielded cable is required for phantom power.

Come back next week when we dive into digital networking and all the different formats in use today.  We’ll also touch on best practices for digital networking and some ways to make sure you don’t get into trouble when connecting multiple consoles together. Feel free to ask any questions that came to mind below, on facebook, or by sending an email to engineers@studiostagelive.com. If you want to be notified when a new post is available, register at this link to receive an email when something has been published. Happy mixing!

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