When it comes to recording quality audio one should never skimp. The trusted standby has always been a wired connection which production sound mixers still use today, especially on Christopher Nolan films. But advancements in wireless technology have significantly closed the quality gap between how wired and wireless connections sound.
Before diving in, we want to clarify that when mentioning wireless, we are talking about the actual transmission signal. Not the type of microphone.
For our purposes, a minimal wireless system consists of a transmitter, receiver, and a microphone. So keep in mind, what you attach to the transmitter—lavalier, handheld mic, boom mic, headset—is something different than the signal itself.
The quality of the microphone can vary greatly. So can the quality and features of the wireless transmitters and receivers. That said, let’s break down the nuts and bolts of wireless.
All the U.S. frequency bands - wireless microphones are only a small part
What is a frequency band?
Wireless devices transmit signals on a frequency band. To explain briefly, frequency bands in the United States are controlled by the FCC. The wireless spectrum is a much larger space but the frequencies designated for wireless microphones, in general, are as follows:
- Low-band VHF 49-108 MHz
- High-band VHF 169-216 MHz
- Low-band UHF 450-806 MHz
- High-band UHF 900-960 MHz
- 2.4GHz band 2.400 GHz - 2.483 GHz
It's important to note wireless systems are not permitted to work entirely on the full frequency band – e.g. 450-806 MHz. This is because certain frequency bands have been allocated for a specific use or they have been auctioned off (more on that later). A simple way to think of it is for each frequency band there a certain number of channels that a wireless system can use to transmit a signal.
Is VHF, UHF or 2.4GHz better?
This topic is worth mentioning. While there are many technical details of each, like wavelength characteristics, here are the basics you need to know.
- The entire spectrum is shared by different users and multiple types of devices
- All signal types whether analog or digital can suffer interference
Low-band VHF 49-108 MHz
Except for things like assisted listening systems and walkie-talkies don’t consider this frequency band for serious wireless applications. It’s very prone to interference among other things. Devices like Comtek use the frequency band with great success.
High-band VHF 169-216 MHz
This frequency band is better than low-band VHF as it has less interference. It’s ideal for small locations or when you have a good line of sight. It’s also capable of penetrating thinner walls and it's decent for car work but it works best with shorter distances. Again, Comtek systems utilize the 216 MHz.
Low-band UHF 450-806 MHz
Flat out, this is the best frequency band available for wireless systems. It offers the most range, widest dynamic range, better power output over VHF, and the most amount of channels. The physical size of UHF wireless can be significantly smaller too. While prone to interference, it suffers the least and can penetrate through walls with the most efficiency.
Typical wireless microphones in the U.S. will operate between 470-600 MHz.
High-band UHF 900-960 MHz
This frequency band offers similar characteristics to low-band UHF but the number of channels is limited. Typical wireless in the U.S. will operate between 941-960 MHz
2.4 GHz band 2.400 GHz - 2.483 GHz
This is a crowded spectrum. Bluetooth, WiFi, cordless phones, security systems, and smartphones run WiFi. Channel counts are usually limited, as is the range of the wireless. Latency can also be a bit higher than UHF systems. However, companies like Deity are changing the way 2.4 GHz wireless systems typically work offering better power output and less interference. These systems are worth considering for less demanding applications.
'Last Days in the Desert' dir. Rodrigo García
Wireless Advantages
The advantages of wireless audio are pretty obvious.
There are no wires.
There’s a ton of flexibility when it comes to placing a microphone on talent or stashing a plant microphone on a set. Installation and setup are usually easier when comparing to longer wired runs. Wireless audio also allows the sound mixer to work remotely and out of the way of the camera. This is most beneficial when shot lists dance between wide and tight angles. Depending on the type of frequency band (UHF, VHF, 2.4GHz) wireless can more easily penetrate through walls.
Wireless Disadvantages
There are disadvantages to going wireless as well. The main drawback companies try to eliminate is interference with the wireless signal, commonly called radio frequency (RF) interference. This happens when an unwanted signal disrupts the wireless channel you are operating on.
It’s like when you’re watching television and someone stands in front of it blocking the view. No good.
Companies try to limit RF interference by using different modulation and receiver techniques. One feature is the ability to scan the location and automatically offer channels with the least amount of interference.
Pro tip: It’s good practice to always perform a frequency scan upon arriving at each location first. If your wireless doesn’t have the feature there are separate RF analyzers worth considering. In larger settings, like studio environments, there is usually a frequency coordinator on-site to coordinate the vast amount of wireless. So if you find yourself on a lot, be sure to check with them about best practices.
Another way companies combat interference is by offering more channels in a single system. Theoretically, the more channels available, the less chance there is encountering interference. This is especially noteworthy because of the shrinking wireless spectrum. No Film School has detailed this before, but for those new on the subject, the FCC has auctioned off different frequency bands in the spectrum to mobile companies eliminating the available spectrum.
Why is the FCC auction a bad thing?
The FFC has auctioned off the 700 MHz band and the majority of the 600 MHz band will be eliminated come July 2020. This shrinks the wireless space and thus increases the chance of interference. The most valuable band being low-band UHF as it can easily penetrate through walls. It’s one of the reasons why mobile companies have scooped up the 700 MHz and 600 MHz bands. Companies are now offering wireless in the 900 MHz band and 2.4 GHz band as additional options.
How to future-proof your purchase
If you live in the United States, be sure to note the frequency band before purchasing. VHF and 2.4 GHz bands are not affected, but for low-band UHF be sure to purchase a frequency range below 600 MHz. Between 470-600 MHz is ideal. If you end up using wireless in the 600 MHz frequency band you will certainly run into interference and it's illegal. You can get fined by the FCC starting July 2020.
Wireless Systems
Now that we have a basic understanding let’s highlight the best wireless systems available today. In choosing, we strictly looked at those designed for film and television. We also only considered kits that include at least one transmitter, receiver, and a lavalier microphone to make the list.
Azden PRO-XR (2.4 GHz) - $249
What we like about it:
- Quick setup for cameras or mobile devices
- Six-step adjustable output gain
- Adjustable transmitter output power
- Range up to 500-feet
- TRS to TRRS adapter cable included
- Rechargeable lithium-ion batteries
- Headphone and microphone jacks
RØDELink Connect (2.4 GHz) - $399
What we like about it:
- 128-bit encryption
- Up to 300-feet of range (line of sight)
- OLED display (on the receiver)
- One button pairing
- Three-level gain control
- AA battery or USB powered
Audio-Technica System 10 (2.4 GHz) - $520
What we like about it:
- Digital 24-bit/48 kHz wireless operation
- Selectable balanced and unbalanced output
- Internal rechargeable 12-hour battery
- Separate headphone port and volume control
- Three levels of diversity assurance
- Automatic frequency selection
Sony UWP-D11 (UHF) - $529
What we like about it:
- True diversity audio
- Quick setup
- 72 MHz bandwidth
- Headphone output
- All-metal construction
- Daylight viewable display
- 5mW or 30mW output power
- Variable output control
- Multiple frequency bands available
Deity Connect (2.4 GHz) - $699
What we like about it:
- 24bit/48Khz uncompressed audio
- Encrypted 24-bit/48 kHz signal
- Easy pairing and configuration
- Comes with two transmitters
- Bidirectional transceiver system
- Selectable output power 100mw/50mw/25mw/10mw
- "Listen-Before-Talk" mechanism
- 10-hour battery life at 100mW
- USB-C quick charge
- 19 ms latency
- Daylight viewable
- Adjustable output Levels
Sennheiser ew 512P G4 (UHF) - $899
What we like about it:
- 88 MHz bandwidth with up to 32 channels
- Range up to 330-feet
- RF output power of 10/30/50mW
- Up to 8 hours of operation time
- With 48 V phantom powering
- Available in different frequency bands
- Plug-on transmitter available
- Compatible with G3, G2, G1 models
Lectrosonics ZS-LRLMb (UHF) - $2,399
What we like about it:
- Digital Hybrid Wireless
- Easy setup
- 50mW output power
- Compatibility modes to use with analog receivers
- 3072 selectable frequencies
- Detachable antenna
- Input gain control in 1 dB steps
- Multiple frequency bands available
Bonus: Best Smallest Smartphone Kit - RØDE Wireless GO (2.4 GHz) - $200
What we like about it:
- Can be used with cameras or smartphones
- Quick pairing
- Omnidirectional mic
- 3.5mm TRS
- Rechargeable internal battery
- Easily clips on
- 3 stage output padding
- 8 can be used in one location
High-End Options
Besides the kit mentioned above, Lectrosonics offers several other robust options for those stepping into more complex workflows. Lectrosonics offers a variety of plug-on transmitters, receivers, and bodypack transmitters small enough to fit in your palm. Zaxcom is another and offers fully digital wireless transmitters and receivers that are packed with features like encrypted audio, and the ability to simultaneously record to a microSD card and ZHD modulation which increases the number of channels in a frequency band.
Similarly, Audio Limited offers features very close to Zaxcom. Plus if you live outside the United States, the Audio Limited wireless can also record simultaneously to a MicroSD card as well. Wisycom should also be mentioned in the group. They offer wideband and narrowband bodypack transmitters that have selectable output power, phantom power, input gain control, and more. Wisycom has ultra-wideband receivers and plug-on transmitters as well.
Lastly, you might be asking where Shure is on this list. Shure delivers very reliable products but seems to have discontinued the Shure FP15/83 series. However, if you're into live performance sound production definitely look into Axient Digital. It's awesome.
Final Thoughts
We all understand the convenience of wireless technology and how great it is for filmmakers. While becoming more common on sets today, it’s important to understand when to use wireless for an application. A wired boom microphone will always sound better than a wireless boom – especially when recording louder sounds. But one day that may change. If you have a favorite wireless system let us know in the comments below.
