ProAVmag

Value Engineering: Don't Cut Corners

Part of my responsibility to the company where I work, and I guess to the AV industry in general through PRO AV, is to pass along what I've learned in my IT career and help close the knowledge gap be 3/03/2008 5:53 AM Eastern

Value Engineering: Don't Cut Corners

Part of my responsibility to the company where I work, and I guess to the AV industry in general through PRO AV, is to pass along what I've learned in my IT career and help close the knowledge gap between the two camps.

Part of my responsibility to the company where I work, and I guess to the AV industry in general through PRO AV, is to pass along what I've learned in my IT career and help close the knowledge gap between the two camps. Whether we're talking technologies, techniques, terms, or best practices, it all equates to knowledge transfer. A couple of the major subjects that have come up a lot lately are IT cable techniques and IT network equipment used in AV. Let's see if we can't tackle both this month.

First up, IT networking equipment. Because most of my professional career has been in the IT side of this world, I've learned through experience the best way to get things right every time when it comes to infrastructure. In short, skimping and cutting corners only lead to problems down the road—much like life in general, I guess. If you asked any seasoned AV tech or engineer, I imagine they'd say the same thing.

Unfortunately, there are situations that don't allow for what could possibly be the best of breed (and perhaps most expensive) equipment. “Value engineering” is a regrettable byproduct of budget constraints. Engineers love to make things work no matter what, and that's commendable. But there are some situations that just don't lend themselves to value engineering, no matter what. When it comes to deploying IT equipment that you know will be used to support AV projects, and which place high demands on a network, the traditional “value” network components will lead to issues. Mix in a lack of networking knowledge and the project can quickly stall with no foreseeable fix.

In projects that involve streaming AV content, for example, using business-class networking components is a definite must—no skimping, no value engineering, period. This also holds true for projects that involve control and other applications sharing the network. In these cases, the use of a managed network switch that can handle multiple virtual LANs (VLANs), and possibly stacking, may be required.

Whatever the case, AV streaming is off limits to value engineering. As far as I'm concerned, if a budget doesn't allow for it to be done right, it should not be done at all. The end result won't meet the ultimate needs of the client. There are plenty of situations I could list that require this level of “high-end” networking equipment—streaming, videoconferencing, complex IP-based control to name a few—but I would recommend at least an unmanaged business-class switch for anything you do.

And consumer equipment should be relegated to home networks only. This is true not only for switches, but also routers, wireless access points, basically every single piece of IT equipment you specify for an AV project. Choose equipment that fits the requirements and budgets of projects, but always choose from the right class.

Once you choose an equipment vendor, stick with that vendor as much as possible. The amount of effort needed to learn how to configure and operate the equipment correctly won't be trivial.

While the concepts are the same across multiple vendors' products, the configuration methods can be quite different. It's always to your advantage to do it once and be able to replicate the success over and over, both from a time and a labor cost perspective.

Obviously you can't always dictate the vendor in a project; the client may, and often does, have a preferred vendor for network equipment. The discussion usually comes down to who will be responsible for the equipment once it is in place. If the baton is being passed to the client, chances are the client will define what you use, based on your recommendations and the functional requirements of the device. Therefore it's important you know your requirements, know how to articulate those requirements, and know when a device will do exactly what is required of it.

THE CABLE FACTOR

Then there's the cabling side of the discussion. The big issue here is how to handle and terminate traditional network cable and unshielded twisted pair (UTP). As I discussed in a previous Data Links (January 2008, page 80), UTP cable is becoming an extremely popular cable for AV infrastructure build-out. While it's just another form of traditional category cable used for decades in IT, it brings along its own set of handling and terminating requirements.



1 2 Next

Value Engineering: Don't Cut Corners

Part of my responsibility to the company where I work, and I guess to the AV industry in general through PRO AV, is to pass along what I've learned in my IT career and help close the knowledge gap between the two camps.

In my earlier discussion of UTP, I mentioned in passing the use of plastic zip ties for securing UTP bundles to each other and to cable management apparatus. This is commonplace on the AV side, but an absolute crime on the networking side. The use of hook-and-loop fasteners is the only sanctioned method.

While it may be argued that this doesn't allow for as tight a securing, that's actually the idea—the wires are not cinched tight against each other, thus not promoting cross-talk between them. Another handling issue is the maximum radius the cable can be bent—one inch. I've seen cable pulled through ceilings by untrained techs and a kink develops in the cable, which in turn is pulled tight. You've just caused a potentially disastrous condition that could render the cable useless.

Every precaution should be taken to carefully handle this cable. It is easily susceptible to damage when mishandled. It may cost just pennies per foot, but a bad run that needs to be re-pulled costs big money in labor.

Another common technique that I would love to squash once and for all is the practice of terminating solid UTP directly with RJ45 connectors. While this isn't an “illegal” practice, it's a bad habit to fall into.

First, most people are not aware that there are two different types of RJ45 connectors—those for solid-core cable and those for stranded-core cable. The difference is in the prongs that either straddle or pierce the core. Using piercing prongs on solid core cable causes the prongs to curl and can lead to intermittent signal passing.

Some might say, “OK then, I'll just buy solid-core RJ45 connectors and be fine.” But I've given both types to people and asked which is which and they were wrong. So if you can't tell, then it's no good guessing. The right way is to always terminate to a keystone jack or patch panel and use a patch cable to do the cross-connect. While this adds cost to any job (jacks, jack housing, etc.), it pays for itself in not having to rectify the situation when an intermittent connection is wreaking havoc.

IT and AV infrastructure have a lot in common, but where requirements differ even a little, doing things the wrong way can make a big difference between success and failure. Make sure the client understands that. And use the right equipment for the job.

Kris Vollrath is vice president of Advanced AV in West Chester, Pa., and an industry consultant. He can be reached at kris@digitaldesignage.com.



Want to read more stories like this?
Get our Free Newsletter Here!
Past Issues
June 2015

May 2015

April 2015

March 2015

February 2015

January 2015

December 2014

November 2014