Last week, we talked about workflow-this week, let's talk about connections. As in, how you hook all that equipment together.
You may have been to larger churches, and noticed they had a pretty clean installation, a few cables were visible, but nothing too messy, right?
If you're like me and go back to your church and look at your installation, you probably have a spaghetti mess of cabling, right? Don't be discouraged! This is normal! In fact, those churches you visited also have a mess of cabling...the difference is they hid it all!
The simple truth is that it takes a LOT of cables to transport all the audio and video signals from their sources to all of their destinations. For example, at my church, we installed a video system in 2000 that ran on S-Video cabling. We have an 8x8 S-Video router with stereo audio. So, I can have 8 separate inputs that I can "route" to 8 separate outputs, with stereo audio. Assuming I have all inputs and outputs connected, I would be looking at a minimum of 32 separate cables. How?
Well, I have 8 S-Video cables going into the inputs, I have another 8 S-Video cables connected to the outputs. I have 8 stereo audio RCA cables connected to inputs, and another 8 stereo audio RCA cables connected to the outputs. 8x4=32...and that's for ONE piece of equipment!
When you add everything up, you'll probably come into the neighborhood of 100-200 separate cables, which is fine, but you need to know how to run them so you're not having bundles and bundles of exposed cables. If you have questions about that, I can give you ideas, but we're already off-topic.
Ok, so connections. First, video connections:
Analog:Composite: This is by far the most common type of video connection I've seen around-usually identified by the color yellow on an RCA cable. Two plug types can be used for composite cables: RCA/Phono (a single male plug, usually round, extending from a round sleeve), or the BNC (a twist-lock connector with a very small single pin extending from a locking sleeve...the female end has a long hollow sleeve with two small posts that the male connector slides over, twists, and locks to). Composite is also known as "video soup," due to the color and brightness information being carried over the same conductor/wire.
S-Video: Also called Y/C, this cable has a four-pin connector and connects one way. A small plastic block extends inside the sleeve with the four small pins and carries luminance (brightness) and chrominance (color) information on two separate conductors/wires.
Component: Also known as YPbPr or RGB, this cable looks deceptively like an RCA cable with audio, though you need to pay attention to the color coding. In truth, an RCA cable and Component cable are interchangeable, but you must remember to match the colors on both ends of the cable and know what kind of signal you're plugging into. Component is the highest quality analog connection I know of. The reason is that it separates Red, Green, and Blue onto separate conductors/wires. Brightness is carried on the Green conductor since the human eye is most sensitive to the color green.
Digital:SDI: Short for Serial Digital Interface, this comes in two flavors, SD (Standard Definition) and HD (High Definition). A digital signal is simply an analog signal that has been converted into a stream of zeros and ones (hence the term 'digital'). A digital signal is also inherently resistant to interference, etc. The reason why this is goes over my head, but I'm sure you can find a broadcast engineer to explain it. :)
Fiber: This is similar to SDI, only that it runs digital signals over fiber-optic cable, instead of copper. A very high capacity connection, fiber is able to use light division multiplexing technology...essentially, equipment that is able to "slice" light into different wavelengths so more information can be carried on it...in short, an extremely efficient transmission medium. The reason we are seeing such high bandwidth Internet services becoming available is due to the installation of fiber-optic cables throughout the country...sometimes even to our doorstep. So, if you're planning to install for the future, I would highly recommend at least researching fiber equipment...it might be cheaper to install it now than to have either re-run cabling in conduit, or worse, rip up flooring and walls in order to get to your cabling.
Ok, now for audio:
Analog:XLR: I'm honestly not sure what the acronym stands for (stereo left/right, maybe?), but this connection is the standard, the workhorse of the industry. Microphones and virtually every instrument and/or piece of audio equipment must use this connection at some point to connect to an audio system. It utilizes three wires (hot, neutral, ground-I think) and is a locking connection, so no accidental "unplugs." It's a fairly robust connection, though the wiring can get damaged fairly easily. It's a balanced input, meaning it can carry stereo signal (left and right).
1/4": Ok, I'm a bit lost when it comes to the venerable 1/4" connector. There are many different flavors, and I don't pretend to know them all. I know there is a TRS (Tip, Ring, Sleeve) designation on some 1/4" connectors, but I'm still not sure what purpose they serve (can someone fill me in?). But I DO know you can get them in mono or stereo configurations, and that will determine how you can use those cables and what you can plug them into. This is the connection that instruments use to connect to a sound system, and it's by and large an unbalanced connection, unless it's stereo (or TRS???). Seriously, I've no idea. hahaha
1/8": A little brother to the 1/4" connector, this would be your computer speakers/iPod connector, which has turned into quite a flexible connector of late. Capable of running three separate signals over this little connector (even video!), it's much more than just an audio connection...but you'll need to understand how this connector fits into your system.
Digital:Cat5: Ok, let's get the easiest out of the way first-you can convert your analog audio signals into digital signals to run over Cat5/6 cables (this is the stuff you use to connect a computer network together) for long distances. The advantages of this over using traditional mic snakes are a many, though I will only outline two of the biggest: form factor-a single cable can carry multiple channels (up to 96, I believe, depending on the audio spec). This saves you a lot of weight since the mic snakes of the past rely on three-conductor copper for every mic channel x how many feet of distance you have (let's estimate a 100 ft. snake with 24 channels...that's close to if not over 100 lbs!). So, a HUGE savings in setup time, weight, space, etc. Ok, factor number 2: Interference: Cat5/6 is naturally resistant to interference (RF-radio frequency and power being the main culprits), which means that if you have a hum in your system or if you're picking up radio stations, replacing some of your copper with some Cat5/6 will at least begin eliminating where the interference is entering your system.
Toslink/Optical: This is similar to fiber, but transmits a red light that carries high-quality audio and is capable of some pretty impressive sound. :)
SPDIF and all others: Ok, this is where I start to lose it on the audio side, I'll admit, but a lot of these connections simply provide you with high-quality transport options so you get the highest quality sound you can.
Ok, next week-what does a system map look like?