Aux Out

By Will Craig

Fear, uncertainty, doubt, and hope are reflected in typical teacher stations, podiums, and classroom equipment racks in the form of auxiliary input/output connector panels. Checking the auxiliary connector panel in a college or university classroom will give you some insights about the room’s system designer.

If you find lots and lots of connectors for all sorts of input and output signals, the designer is probably overly-cautious about trying to provide a flexible system. As a result of past projects where users complained about lack of inputs/outputs, they prefer to err on the side of connectivity.

If there are only a few connectors, the designer is probably confident in their understanding of the current and future needs of the end-users. Or they were dealing with stringent budget constraints in terms of the signal routing and distribution. Or both.

In order to figure out what auxiliary input/output signals are necessary for your systems, check the following partial list of common auxiliary input/output connectors and why you might use them:

System Inputs:

Wired microphone jack (XLR 3F): If you are using wireless microphones, this is a must for when the batteries are dead. If you have a gooseneck microphone on the podium that isn’t accessible to an instructor sitting at the podium, a wired, handheld microphone would provide a reasonable accommodation for that contingency.

Composite video (BNC or RCA): For when an instructor needs to show a laserdisc, a PAL or SECAM video, a camcorder tape, or other infrequent video source. While commonly seen in auxiliary connector panels, it is often not necessary where a VCR/DVD combination unit is being used, as most of these units have a front-panel auxiliary audio/video input built-in.

VGA (HD-15): Useful for answering questions like “what if we bring in another laptop?”, or “can my assistant operate my computer in the back of the room?” VGA inputs are also useful for connecting to interactive remote conferencing servers or codecs.

USB : USB2.0 jacks provide a convenient way to allow for external computer control devices/remotes, memory sticks, or digital audio devices.

Line level switched inputs (1/8” stereo mini jack or RCA): Audio to accompany video or computer presentation sources.

Mixed line level (unswitched) input (1/8” stereo mini jack): Allows use of a portable audio device for music playback, which could potentially accompany a switched program source rather than being an either/or choice.

Codec line level input (RCA): For when the portable videoconferencing/ITV cart is rolled in. This should be routed into the sound reinforcement bus on your room mixer. You will need a second bus for the audio output to your codec, below.

System Outputs :

Record output (microphone and/or line level; XLR-3M, RCA, 1/8” stereo mini): If you have an audio distribution amplifier, additional/extra audio output jacks are almost free. Consider those who want to record their own lectures/classes using iPod recording modules, portable tape recorders, or their laptop/tablets. It also provides a clean audio output of both microphone and program audio for your streaming/archival system.

Assistive listening audio output (line level; XLR-3M, RCA, ¼” mono): If you don’t have a dedicated transmitter in each room, this allows for a portable transmitter to be connected to the sound reinforcement system.

Composite video (RCA or BNC): The switched feed from the room’s cameras, VCR/DVD, document camera, or other presentation sources can be routed to a video encoder/archiving device. This can potentially be used in conjunction with the composite video auxiliary input in terms of adding a live open captioning capability using a portable captioning station.

VGA (HD-15): The computer graphics output can be routed to recording or encoding/archival devices. Also, this can be useful if positioned appropriately for providing an output for a large-monitor cart, in order to provide accommodation for the visually impaired.

Control port (various connectors): Allow for connection of a wired touch screen controller, to supplement the room’s existing controller, or to provide a technician with an appropriate interface that they would bring with them from room to room. Leading manufacturers offer proprietary control protocols, such as CresNet and AXLink.

Codec audio output (RCA): This is the output side of the portable codec connection. Your room mixer will need at least 2 buses/output channels: one (or more) for local sound reinforcement, and one for codec output, which d'es not include the input from the codec in the mix. Alternately, you could use a multiple-mixer arrangement.

Having the necessary input/output jacks is only the first step. Deciding where in the room the jacks should be located is the next challenge. Every situation has to be handled on a case-by-case basis, so here are some questions to consider:

What types of devices will the instructor need to connect right at the podium, versus items that might be connected by an assistant or a technician somewhere else in the room?

If cart-based portable equipment is to be used, where is there physical space for the cart to be positioned, both when in use and when it is stored?

Is there a secure but accessible (yes, I am aware this is somewhat contradictory) place where the connection cables can be stored?

Next, pick out the connection panel itself. Tens of thousands of blank rack panels have been drilled, punched, cut, and engraved to good effect to create customized connector panels. Another approach is to use a modular system, like Middle Atlantic’s UCP system or Raxxess’ Modular Panel system. Either way, the benefit is that you can swap out individual connector modules without having to replace the entire panel. If rack-mounted is not necessary or feasible, gang-style wall plates can also be used inside furniture or in floor boxes.

Lastly, don’t forget about labeling. A connector panel can cause a simple system to look more complicated, just by virtue of having a bunch of scary-looking connectors with no clear purpose. Label, label, label. Use graphical icons where possible to make connectors less scary-looking.

Don’t underestimate the importance of “de-scary-fication.” A fine arts professor commented to me a few days ago that her impression of her institution’s standard smart classroom is that it is extremely complex to operate because “there’s this big tall black rack with lots of things and wires in it, and I have no idea what I have to do to make it all work.” While most educators would envy the ease-of-use afforded by this institutions’ simple podium with large touch screen control interface, emotional impressions are easily made and hard to break. If a typical user d'esn’t need auxiliary inputs/outputs, consider placing them so that they are not front-and-center. Keep in mind that these are, after all, AUXILIARY, and that they should not detract from the effectiveness of the system by making the system look too complicated to use.

Will Craig CTS-D CDT, is a Multimedia Systems Consultant with Elert & Associates, an independent technology consulting firm working with higher-education clients across the United States.

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