Tuesday, February 5, 2013

New wireless system

I got a question about new wireless gear for a very small church.  Here's my answer, in case it might benefit you.  Note that there are things such as gain structure and RF interference that aren't really covered by this post - this was intentional.

I would check if you need new wireless first.  The 2 most common problems I hear are RF issues (RF dropout or RF clipping) and audio clipping.  RF dropout sounds like bursts of static that happen at random.  You can ease these problems by selecting a different wireless channel (if possible).  You can also help by keeping the antennae of the receiver away from metal and sources of noise (like switched mode power supplies) and by keeping the antennae at 90 degree angles to each other.  It is possible that the RF signal is too powerful and the solution is to either decrease the transmit power (which likely isn't possible) or to move the receiver farther from the transmitter.  This has never been a problem in my experience, but more experienced sound folks have run into it.  Note that all of my practical experience is with Shure ULXP and Shure PGX systems.

Audio clipping is when the microphone transmitter audio gain is too high.  You will only hear the distortion when you talk louder than a certain volume, and never when the volume is below that level.  This can be fixed by lower the gain, usually using a switch or rotary pot on the transmitter.  You will likely have to increase the gain on your mixer to counter the loss of gain at the transmitter in this case.  My advice is to start with the lowest setting on the transmitter and use the console gain to get the rest of the way, though you may have to experiment a bit.  If you find yourself really cranking the console gain just to get any audio out, try the next higher audio gain setting on the transmitter.

If you are using a lavalier system, it is possible that you need a new lavalier microphone.  This is hard to test because you either need a known-good wireless system for the microphone, or even better, a known-good microphone to test in your wireless system, and they all have to have compatible connectors.  I don't know where you're supposed to get either of those with compatible connectors, but it could be worth exploring.

Even if the problem is only the wireless system or the microphone, you may still want to replace everything at once rather than trying to spend money to upgrade an old and shaky system.  Also, it may be a good time to evaluate if you need wireless or if you can replace old wireless with a new, hardwired microphone.  You can save on initial cost as well as battery costs, and it make things much simpler.  And if you only need a wired mic, then you've already wasted your time reading as far as this sentence.

If you're doing a completely new purchase, I would go with the Shure PG or PGX lines.  If you want to use an existing lavalier microphone with the new wireless system, you'll have to get a wireless brand that works with your existing connector.  Shure PG systems are cheap while still being okay.  You do have to manually assign wireless channels to the transmitter and receiver, but they do have a nice dual-receiver package if you need a multiple of 2 channels.  Shure PGX systems can scan for the best frequency to use and then use an IR sync system to assign that channel to the transmitter.  The downside is that the receiver has a very large button that is easy to press on accident, which means you have to re-do the channel assignment.

I pick on Shure because in my experience they're a solid brand from top to bottom and are novice-friendly, at least at the level of wireless systems this post is meant for.  Sennheiser is another solid brand, but I sometimes have a bit of trouble understanding how their products fit together.  My only experience with Telex gear is slight exposure to old Telex wireless systems, nothing current.  There are some other really great brands for wireless gear, but some of them can get very complicated and expensive, so I'll likely never get to use them myself.

You will have to select a frequency band for your wireless system.  My advice is to download software from the manufacturer site which can tell you about RF conflicts.  Shure's version is called Wireless Workbench.  Manufacturers may also have a basic web interface you can use to determine the maximum number of wireless systems you can have based on your location - pick the band that allows you to have to most systems because that's the band with the least interference.  Neither of these tools can predict localized sources of interference, however, so if you're surrounded by folks using various wireless systems, you may want to coordinate a bit.

If you're getting a handheld wireless mic, then it's pretty easy with most manufacturers - get the handheld that goes with the receiver (or receiver that goes with the handheld).  If you're going to get a new wireless system that includes a lavalier microphone, you have some more options.  You still have to get matched bodypack transmitter and receivers, but you can either go with one of the microphones from the manufacture for that system, or you can get a mic of your own choosing.  If you get a microphone of your own choosing, make certain that it has a compatible connector with the wireless system you've selected, otherwise they won't work together.

Whatever you do get, be sure to take care of it.  When you store it, leave plenty of slack in the cord around the connector, don't try to wind it tightly.  Also, mic placement can have a large impact on your sound quality.  For lavalier mics, I tuck my chin to my chest and place the mic within a couple centimeters of where my chin touches my chest.  Feel free to experiment to find what works best.  Also, NEVER walk in front of the speakers with a mic that's turned on.  Positive feedback is not your friend.

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