The team at Shure Microphones offer up a complete guide to Wireless Microphones and Wireless transmitter systems
The team at Shure answer some of the most common questions they get asked in this Shure Wireless Guide - courtesy of Shure Applications Engineer, Tom Colman. Thanks to Shure for sending in the content!
As a performer, you understand that your microphone is the first device in the signal chain; anything that happens from that point will directly affect the final show, production, event or meeting. As you are responsible for ensuring the audio remains uncompromising, you know the importance of retaining access to clean, high-quality RF Spectrum.
We now live in a connected world, where consumers expect instant connectivity across a multitude of devices. Mobile phones, tablets, etc are known as whitespace devices, and the connections these devices provide will directly effect our wireless transmissions. The power and convenience that brings to our daily lives is undoubtedly important, but it also means the RF spectrum has never been in such widespread use by the general public.
Frequencies You Can Use For Wireless Microphones & IEM’s
Wireless microphones and in-ear monitors operate in dedicated blocks of spectrum. In the UK, the majority of systems operate in the so-called UHF bands but there are a few other parts of the spectrum that are available for wireless systems.
- VHF radio microphones generally operate between 175MHz and 225MHz and provide users with great propagation characteristics where available. To provide users with additional options in today’s congested RF environment, Shure recently announced VHF versions of QLX-D & ULX-D.
- 470-606MHz (TV Channels 21-37) and 614MHz-790MHz (TV Channels 39-60) are available for wireless microphones and IEM’s on an interleaved basis. These blocks of spectrum are generally used for large events; you will require a licence for legal operation.
- TV Channel 38 (606-614MHz) Note: A licence is required by law to legally operate wireless mics and IEM systems in Channel 38. Channel 38 is shared spectrum with other users of PMSE equipment and is available across the UK. Please contact OfCom to obtain a license.
- The deregulated licence-free spectrum from 863-865MHz remains available. Shure recommends the use of 2.4GHz systems over 863-865MHz.
- The 1.8GHz band of spectrum is available in the UK as part of the Channel 38 licence. Shure now manufacture 1.8GHz versions of QLX-D and ULX-D.
- The 2.4GHz band is available for use across the UK and is licence-free. The band is ideal for small channel counts and environments where a long distance transmission is not required.
A Guide To Shure Wireless Products
The entry-point for professional Shure wireless. The Shure Analogue BLX systems deliver great performance, right out of the box.
BLX Wireless Frequency Bands/Versions
- K3E* Covers TV Channels 38 – 40 606 – 630MHz
- K14 Covers TV Channels 39 – 41 614 – 638MHz
*Available for use with a Channel 38 licence
K3E: Twelve compatible frequencies per band (region dependent).
Which frequency version should I purchase?
The primary UK frequency version is K3E. This version covers TV Channel 38. For fixed-site installations, users may choose the K14 version as this operates only in the interleaved spectrum.
View all Shure BLX Wireless Systems at PMT Online.
GLX-D® Digital Wireless
The Shure GLX-D Digital Wireless systems allow you to step into digital audio clarity with advanced wireless management features previously reserved for higher tier systems.
GLX-D Wireless Frequency Band/Version
- Z2* Covers 2.4GHz Band
How many systems can I use together? Up to five systems can be used together without Shure’s Interference Detection and Avoidance. This technology seamlessly moves away from interference to backup frequencies with audio interruption. Eight systems can be used together without backup frequencies. This should only be used in controlled Wi-Fi environments.
What’s the key benefit of choosing 2.4GHz? GLX-D operates within the 2.4GHz band, which is utilised by Wi-Fi, Bluetooth and other wireless devices. The benefit of 2.4GHz is that it’s a global band that can be used anywhere in the world, licence-free.
View all GLX-D Wireless systems over at PMT Online.
The Shure GLX-D® Advanced wireless system is the next level in GLX-D digital audio clarity. The rack mount receiver and frequency manager system features intelligent rechargeability and seamless operation for a diverse range of applications.
GLX-D Advanced Wireless Frequency Band/Version
- Z2* Covers 2.4GHz Band
How many systems can I use together? Link up to nine GLXD4R receivers in typical application environments (up to 11 under optimal conditions). Two GLX-D Frequency Managers required for communities of more than six receivers.
View all Shure GLX-D® Advanced wireless systems over at PMT Online.
24-bit digital audio with professional features and simplified operation; QLX-D offers outstanding wireless functionality for demanding live sound events and installations.
QLX-D Wireless Frequency Bands/Versions:
- K51* Covers TV Channels 38 - 44 606 - 670MHz
- G51 Covers TV Channels 21 - 28 470 - 534MHz
- H51 Covers TV Channels 29 - 36 534 - 598MHz
- L51 Covers TV Channels 41 - 78 632 - 696MHz
- V51 Covers (N/A) 174 - 216MHz
- Z18* Covers (N/A) 1785 - 1805MHz
K51: Twenty-two compatible frequencies per TV Channel, i.e. Channel 38 (region dependent).
What frequency version should I purchase? We suggest K51 as this is the primary UK version that covers Channel 38. Note that a licence is required to operate wireless microphones in Channel 38.
PSM® 300 In-Ear Monitoring
The Shure PSM® 300 In-Ear Monitoring systems offer wireless stereo monitoring with detailed 24-bit digital audio processing. Easy to use, PSM300 offers custom control of a personal mix from two channels of audio.
PSM® 300 Wireless Frequency Bands/Versions
- K3E* Covers TV Channels 38 - 40 606 - 630MHz
- H8E Covers TV Channels 27 - 29 518 - 542MHz
- L19 Covers TV Channels 41 - 43 630 - 654MHz
K3E: Fifteen compatible frequencies per band (region dependent).
What frequency version should I purchase? We suggest K3E as this is the primary UK version that covers Channel 38. Note that a licence is required to operate wireless microphones in Channel 38.
View all Shure PSM® 300 In-Ear Monitoring systems over at PMT Online.
Digital Wireless FAQ:
Digital wireless systems are increasingly common in the world of professional and semi professional audio. Their growth over the last few years is the result of many factors, from the continual pursuit of better quality sound to the increasingly pressing issue of RF spectrum clearance.
Like other areas of the audio world, though, the debate as to whether digital is better than analogue, or vice-versa continues to spark much debate, causing a plethora of misconceptions, and/or questions. To help settle the debate, at least for a while, Shure Applications Engineer, Tom Colman has kindly answered some of the most common questions we receive about digital wireless systems.
1. Why do I need digital wireless? My gear works fine!
Two words; spectral efficiency. Demand for wireless microphones increases year-on-year, while at the same time, the amount of clear spectrum available is shrinking. More mics in less space means it’s going to get crowded pretty quickly, and the amount of radio ‘space’ each channel takes up needs to be reduced to keep up with demand. Wireless spectrum, after all, is a finite resource; there is only so much to go around. If the demand for wireless products across the board continues to increase at the current pace, all users will need to be more spectrally efficient (including consumer goods).
It’s a bit like lanes on a motorway. Previously we had, say 8 lanes, and only 3 large trucks needed to run simultaneously; not much traffic and plenty of space. Now we have 4 lanes and we’re trying to run 20 trucks side-by-side; there’s not a lot of space. Using efficient digital systems, it’d be like running 20 very narrow trucks in the same 4 lanes; a solution that will actually work.
2. How does the audio compare? Is it true that digital wireless doesn’t sound as good as analogue?
The age-old analogue vs digital question is always laced with subjectivity. For wireless mics though, it’s more objective. On the whole, digital radio microphones will have more low-end, top-end and argubly sound more transparent than analogue. This is due to a couple of reasons. Analogue systsems are bound by the limitations of FM modulation, such as limited frequency response. The lack of top-end is particularly noticeable on bodypacks used for instruments with lots of high-frequency content. The frequency response of our digital systems is 20Hz - 20KHz, which results in very full sound.
The other thing is, digital systems are not subject to noise picked up while being transmitted. In a digital transmitter, the first process applied to the incoming audio is the analogue-to-digital conversion. Now that the audio is represented in 0’s and 1’s, the transmitter will use what is typically a proprietary form of digital modulation to send this data. As the data being transmitted is digital, the receiver can perfectly recover the digital 0’s and 1’s, thus resulting in a perfect reconstruction of the original analogue sound - as well as avoiding pick up noise. The process also allows the frequency response to be much wider than analogue as we are no longer bound by the limitations of FM modulation.
3. Does WiFi interfere with digital wireless?
Interference is always a concern when multiple services are sharing spectrum. Just like in our motorway example earlier, if there’s more than one car on a main road then a collision is possible. Our GLX-D system use the same spectrum as WiFi (2.4GHz), meaning there is a chance of interference. To counteract this, we need specialist technology that continually scans the 2.4GHz landscape to hunt out and avoid interference, leaving you with perfectly clean, interference-free audio.
4. Does digital mean no interference?
For UHF based digital wireless systems, you need to coordinate your system to avoid external sources or interference in the same way you would an analogue system. The factor that swings in your favour, though, is the spectral efficiency of the system; so in the instance of getting interference, you are more likely to be able to avoid it. It’s because of the ‘footprint’ of digital wireless is way smaller than analogue, giving it more space in which to operate.
Some, more advanced digital systems (such as Shure ULX-D and Axient Digital) have frequency diversity built-in. This permits two bodypacks to be used on two channels as a pair, to mic up one presenter for example. The audio from both packs is assessed by the receiver, and at any one moment, the best quality audio is routed to the receiver’s XLR and Dante outputs, so if one pack goes bad, then the good pack’s audio remains on.
5. How many systems can you use together?
The amount of systems you can run at any given time depends on the system you’re using and the spectrum it operates in. To give you an exmaple, a Shure GLX-D system allows you to use up to 8 systems together, but this requires the 2.4GHz spectrum to be super clean. In normal circumstances, I would recommend using up to 4 systems together. If you need to regularly use more at once, then I’d (carefully) recommend using BLX or GLX-D Advanced, or making the jump to QLX-D.
Higher-end UHF systems (such as ULX-D and Axient Digital) are only really limited by spectrum availability and the RF coordinators experience. Both systems offer a High-Density mode, which can significantly increase channel count under the right conditions.
6. Does digital wireless still require antenna distribution and if so, can I use my existing distro/antenna?
GLX-D has fixed antennas and so does not need Antenna Distribution. That said, please still pay attention to antenna placement:
- Try to ensure line-of sight
- Minimise transmission distance
For UHF based systems, providing that your distros cover the RF range that your kit operates on, you’ll be fine.
7. What’s the range on digital wireless? Is it less than analogue?
The digital UHF systems have a similar range to other analogue UHF wireless microphone systems. There’s no difference in carrier frequency; the only difference is it’s carrying digital information rather than analogue. Systems operating in the 2.4GHz band use a higher frequency to transmit audio and so will have a lower, smaller operating range. Physics is physics.
Note: The operating range of any wireless system is largely influenced by the quality of your antenna selection and placement; in other words, following general best-practice when setting up is imperative.
8. Is it licence-free because it’s digital?
The 2.4GHz band is a licence-free part of spectrum and is available globally. Its limitations are the number of wireless microphones it can host; about 8 maximum. It’s also relatively susceptible to interference as there are many other devices that use this band (mainly phones, tablets and laptops using WiFi). For this reason, we must build in features to avoid being caught out by interference (Interference Detection and Avoidance) as described in point #4.
Wireless systems operating in the UHF bands require licencing just like any analogue radio microphone would; either a channel 38 licence or a site-specific licence.
9. Why would I need encryption?
Radio microphones are used at a large number of events where sensitive information is shared. Without encryption, it’s possible to receive the signal from a radio microphone on a separate receiver tuned to the same frequency and with a similar modulation scheme (digital or analogue as appropriate).
As unlikely as it may be that anyone would spy and try to steal sensitive information, it unfortunately does happen in the interests of gaining a competitive advantage.
10. Can I Send It Over My Existing Digital Audio Network?
A digital radio microphone system refers specifically to the RF modulation scheme. In the receiver this is converted into an analogue audio signal for connection to an analogue desk or guitar amplifier.
There are an increasing number of applications where keeping the audio in the digital domain has advantages. Shure have teamed with Audinate to use the Dante Digital Audio Network Protocol.
Only our ULX-D dual and quad receivers (and Axient Digital receivers) have this capability. The audio from these receivers can be streamed via a network to other Dante receivers. (While confusing at first, the receiver becomes a Dante transmitter). Remember that there are specific network requirements in order to do this; primarily a low-latency gigabit network with Quality-of-Service features engaged.
Want to know more? Need to know how to use a wireless guitar system? View our complete guide to wireless systems and frequencies in our blog.
View a complete selection of Shure wireless systems over at PMT Online or call in to your local PMT store today to discuss the best options for your live needs.