Seven Reasons that your wireless systems don't work.

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Seven Reasons that your wireless systems don't work. 

Is there anything worse that a wireless microphone that doesn't work properly?  I can't think of many. 

Take a look at the following article from Shure's Applications Engineering team to discover ways to help make your wireless microphone systems work more effectively.  Some of these are pretty basic, but it's never a bad time to get back to basics, so I think that you'll find it valuable. 

A few weeks ago, one client found out that his monitors weren't working because the monitor equalizer was turned off.  He just assumed that it was on, since everything else in the rack was powered up. 

Reason #1: Dead or weak batteries
How to check: 1) Substitute new, fresh, brand-name alkaline batteries. 2) Examine the wireless mic battery terminals to make certain they are making a secure contact to the battery terminals.

Reason #2: Operating frequency range of the wireless receiver does not match the operating frequency range of the wireless mic/transmitter
How to check: Find the operating frequency range marked on the receiver, e.g., H6 524-542 MHz. Check the wireless mic/transmitter for the same frequency range. The frequency ranges must match exactly.

Reason #3: Failure of an audio interconnect cable
How to check: 1) Substitute another cable of the same type. 2) Use an ohmmeter to check the cable for a shorted wire or an open wire. 3) If using a body-pack transmitter, substitute another lapel mic or head-worn mic of the same model.

Reason #4: Operating frequency is not appropriate for the location
How to check: 1) Using the zip code of the location and the model number of the wireless system, consult the Shure Wireless Frequency Finder web tool to determine recommended frequencies. 2) Use the SCAN feature of the wireless receiver to find an open frequency.

Reason #5: Local interference from other electronic devices or wireless systems
How to check: 1) Turn off any electronic device that is within 5 feet of the wireless receiver, such as a DVD player, a CD player, a computer, an iPod, a wireless router. 2) Remove the wireless system and take it to a different location at least ½ mile away. If it works OK there, the problem is local interference in the original location. Finding the source of local interference often requires the use of a frequency spectrum analyzer - an expensive piece of test equipment.

Reason #6: Improper installation of the wireless receiver or its antennas
How to check: 1) Determine if there is clear line-of-sight, at all times, from the location of the wireless mic transmitter to the receiver antennas. If there is not, the installation could be suspect, though hidden antennas can work satisfactorily if installed correctly. 2) Have the installation evaluated by a local wireless microphone expert.

Reason #7: Failure of the receiver's external power supply
How to check: Substitute another power supply of the same type or with equivalent electrical specifications.

With the explosion of wireless devices (phones, tablets, wireless mics, wireless internet, etc.) over the last few years, using best practices when selecting and using wireless systems is even more important than ever.  If you have questions about how to make your wireless gear work as well as possible, please call us.  We have lots of tools that make our job easier. 


Why Hire an Integrator

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by Mike Sessler,

I was recently asked by a reader for some suggestions on helping his church's leadership understand the need to hire an integrator for new building project. If you've read this blog at all, or listened to ChurchTechWeekly, you know it's something we talk about a lot. Sadly, most churches don't do this well. In the case of our reader, his leadership thinks that they can do the job in-house, and things will be just fine. As someone who has been working in churches a long time (20+ years), I can tell you that in-house jobs rarely end up in the same zip code as fine.

Now, to be sure, there are some churches that can tackle an in-house install. Typically those churches are fairly large and have multiple technical personnel on staff. That technical staff has collectively many years of experience doing design, and installing equipment. They also have a great relationship with an equipment vendor who they can ask advice on things they don't know about.

Those churches are rare, however. Most churches are smaller with less experienced (if any) technical staff. Now make no mistake; I think the small-church technical leader or volunteers are real heroes. They get stuff done in the face of non-existent budgets, time and equipment. But there is a vast difference between making things happen on a weekend and designing and installing a full-blown A/V/L system in a new (or renovated) building.

Designing a full system takes a lot of know-how, and requires an encyclopedic knowledge of equipment. Given the wildly varying standards we're dealing with right now, it's far too easy to end up with systems that won't work together. Designing speaker systems is far more complex than hanging a few boxes in the air (which also needs to be done safely), and typically DIY projects are less than desirable.

As someone who for whatever reason seems to be the Mike Holmes of church tech, I can tell you've I've pulled out a lot of gear that was installed by well-meaning but terribly uninformed people. It can take years and hundreds of thousands of dollars to fix mistakes that were done in the name of saving money. Don't do it!

Here are the top five reasons you should not do it yourself. Feel free to send this link to your pastor...

Read more: Why Hire an Integrator


Shure Apps Tech Tip: Microphone Distance Factor

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What is the Distance Factor for a microphone? In brief, it means that a directional microphone may be placed farther away from a talker than an omnidirectional microphone and still produce similar audio results. This assumes two microphones of equal quality and sensitivity.

As an example of the Distance Factor, let's consider a simple application: recording a talker's voice in a meeting room. Through experimentation, an omnidirectional mic is found to produce an acceptable recording when placed 2 feet away from the talker.

Acceptable recording = minimal level of background noise in relation to the talker's voice level. Rule of thumb: the talker audio should be at least 20 dB louder than the background noise.

Now try a cardioid microphone in place of the omnidirectional. The Distance Factor for a cardioid is 1.7. This means the cardioid may be placed 1.7 times the distance of the omnidirectional and produce the same audio quality. In this example, the cardioid may be located 3.4 feet away (2 feet x 1.7) from the talker and produce an acceptable recording. The Shure KSM141 is the perfect microphone for this experiment as it can be switched from omnidirectional to cardioid.

Next, try a supercardioid mic in place of the omnidirectional mic. The Distance Factor for a supercardioid is 1.9. So it may be placed 3.8 feet away (2 feet x 1.9) from the talker and produce an acceptable recording.

Then, put a hypercardioid microphone in place of the omnidirectional. The Distance Factor for a hypercardioid is 2.0. It may be placed 4 feet away (2 feet x 2.0) and produce an acceptable recording.

Finally, try a shotgun microphone in place of the omnidirectional microphone. The Distance Factor for a typical shotgun is 3.0, which allows the microphone to be placed 6 feet away (2 feet x 3.0) from the talker and produce an acceptable recording.

Remember that the Distance Factor is a multiplication function that directly relates to the audio quality obtained with an omnidirectional mic in a given acoustic environment. If an omnidirectional mic must be used at 1 inch from the talker for acceptable results in a noisy setting, then a hypercardioid mic must be used at 2 inches for the same results... not, not, not the 4 feet mentioned in the previous example above.

IMPORTANT: The increase in Distance Factor for a directional mic is due to its greater rejection of ambient (background) noise, not due to any increase in sensitivity to the desired sound source. In other words, the directional mic does NOT reach out and grab the sound emanating from the talker's mouth. Really, it does not…

When a mic is placed farther from the talker, more amplification is necessary to maintain the same output level. In a public address application, it is loudspeaker positioning that often dictates microphone location and overrides the Distance Factor in determining the maximum distance from microphone to talker.

Omnidirectional = 1 Cardioid = 1.7 Supercardioid =1.9
Hypercardioid = 2.0 Shotgun = 3.0



Shure Tech Tip: A Small Slice of Ohm's Law

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The sound system designer required the power consumed (in watts) from each Shure product in the design. This information was required to satisfy the local electrical inspector that the sound system would not overload the electrical circuits in the vintage building. In most cases, the watts rating can be found on the Shure User Guide for the product. If it is not listed, it can be calculated; all that is required is simple multiplication. First, here is a lesson in basic electronics using water as the analogy:

Current, measured in amperes, is the amount of water flow.

Voltage, measure in volts, is the water pressure.

Power, measured in watts, is the amount of work the water can do.

Water power is "water pressure" multiplied by "water flow."

Electrical power is "voltage" multiplied by "current."

Example 1: A kitchen toaster needs 120 Vac (volts alternating current) to operate and consumes 10 amperes. 120 multiplied by 10 = 1,200 watts.

Example 2: The Shure UA844SWB needs 18 Vdc (volts direct current) to operate and consumes 3 amperes. 18 multiplied by 3 = 54 watts.

Example 3: The Shure ULX4 needs 15 Vdc to operate and consumes 0.550 ampere (550 milliamps.) 15 multiplied by 0.550 = 8.25 watts.

The math also works in this way:

Example 4: The SCM800 is rated at 24 watts when connected to a 120 Vac source. 24 divided by 120 = 0.2 ampere or 200 milliamps.

If the voltage and amperes are known, the wattage can be calculated. If the wattage and voltage is known, the amperes can be calculated.


Wired Guitar + Wired Microphone = Electric Shock

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A Tech Tip from Shure Applications Engineering:  

The musician was bewildered…more than usual. "When my guitar is connected to my amp with a cable, and I sing into a wired mic, I get an electrical shock through my lips. If my guitar is wireless, it does not happen. If my mic is wireless, it does not happen. Why do I get shocked when the guitar and the mic both use a cable?"

Of course, the mic gets blamed because it touches the lips. But the culprit is not the mic, nor the cables. The culprit is the guitar amp.

Because of the electric design of many vintage guitar amps, it is not uncommon for a small amount of current (120 VAC) to "leak" onto the amp chassis.

Read more: Wired Guitar + Wired Microphone = Electric Shock


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