Wireless Audio Demystified: Sony’s Markus Warlich on 2.4 GHz vs UHF, Real 32-Bit Float and the Shrinking Spectrum – Focus Check ep140

by Felix TappeinerToday

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Your 32-bit float wireless mic might not be recording 32-bit float at all. To our pleasant surprise, this week’s episode turned into an unofficial wireless audio masterclass: Markus Warlich, who has worked in pro audio at Sony since 1997, explains that no 32-bit A/D converter exists, so a real 32-bit float recorder needs two stacked 24-bit converters. He says, at least one manufacturer simply “upgraded” a 24-bit system via a software update. Meanwhile, the UHF band professional wireless depends on has nearly halved since 2012, and nobody can promise it will survive beyond 2031.

Instead of our weekly news round-up, Nino sits down with Markus Warlich, Head of Pro Audio at Sony Europe. Our IBC 2026 video with Markus on Sony’s DWX Gen 4 turned into our most-watched video from the show, so we invited him back for a long-form conversation about audio for camera people. We work through why every shooter now owns a wireless kit, what really separates 2.4 GHz from UHF, latency and audio quality, Sony’s own lineup from the ECM-W5 to DWX, the shrinking UHF spectrum and the World Radio Conference, travelling with wireless gear, what 32-bit float can and cannot fix, and the mistakes Markus sees from customers every day.

This episode is sponsored by Hollyland – check out the Pyro S wireless video transmission system on their website. (11:14 in the episode)

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From PA stages to Sony – and why everyone shoots wireless now

(01:08 in the episode)

Markus started out in 1988 co-founding a PA, lighting and staging rental company, moved into sales in 1994, spent a few years at Harman and joined Sony’s pro audio business in 1997. Asked why the cabled lav has all but disappeared from camera bags, he points to two decades of falling prices and the freedom to move – “humans are lazy”, he jokes.

There is a quality argument too. As images got better, so did expectations for sound, and covering two or three speakers with a single shotgun gives you little control in post. Separate wireless channels do.

Read more: Sony DWX Gen 4 Detailed – our IBC interview with Markus

2.4 GHz vs UHF: a shared spectrum versus a channel of your own

(05:38 in the episode)

According to Markus, the difference comes down to two things. 2.4 GHz is shared with every Wi-Fi and Bluetooth device in the room, and it was designed for data packets that can simply be requested again – something real-time audio cannot do. UHF, by contrast, gives you a frequency of your own once the receiver has scanned for a free one. Second, the short 2.4 GHz wavelength does not pass through bodies, walls or even the metal in a monitor: with line of sight it is fine, but turn around and the link can drop after 10–50 m.

Advertised ranges of 250–500 m are achievable “in the desert”, not at a wedding where an uncle switches on his own wireless kit at exactly the wrong moment. Markus puts the practical limit at two or three 2.4 GHz systems per room, against up to around 100 UHF channels – and only UHF currently lets one transmitter feed many receivers, although Bluetooth 6 and Auracast are starting to change that.

Latency and audio quality: the microphone is your lens

(21:48 in the episode)

Most 2.4 GHz systems sit at around 40 ms of latency, roughly two frames. Cameras from the same manufacturer can compensate using metadata from the receiver, but anyone monitoring on set still sees and hears a mismatch. Sony’s DWX started at 3.5 ms and is down to 1.1 ms with Gen 4. For musicians on in-ear monitoring, Markus cites an AES study putting the limit for the whole chain at 5–6 ms – UHF territory only.

On quality, 2.4 GHz actually has more bandwidth in theory, so the codec decides. Markus’ bigger point is that audio carries the emotion: “the microphone is your lens”, and while viewers stay when the picture drops out, they switch away when the audio goes.

When to use 2.4 GHz and when only UHF will do

(28:30 in the episode)

2.4 GHz won the consumer market because it is licence-free worldwide and needs no frequency planning. UHF between 470 and 694 MHz is, in Europe, primarily television spectrum, with radio mics as secondary users that authorities want to know about. Markus’ honest case for 2.4 GHz is setup time: a wedding where you have ten seconds, or the COVID era, when a magnetic transmitter could be handed over without touching anyone.

For trade shows, handhelds and plug-ons, more than four channels, rack-mounted receivers or film sets where the sound department distributes feeds, it has to be UHF. For ENG and news, his answer is “you need both” – some European broadcasters already carry a 2.4 GHz kit as a backup next to their UHF system. Nino adds that on trade show floors only a UHF handheld has given us a reliable link, and both agree on the basics: wear headphones.

Sony’s own lineup: ECM-W5, UWP-D and DWX

(40:39 in the episode)

Markus’ first question to customers is about the job. Never more than two channels on an Alpha, FX3 or FX30? Try 2.4 GHz. A dedicated sound person on the crew, or ENG and news work? UWP-D. Film and the best possible audio quality? DWX.

Asked why Sony claims the new ECM-W5 is around three times more stable than the ECM-W3 despite using the same band, he explains that newer transmitter and receiver chips send and detect the data far more precisely, and he believes the W5 also has slightly higher output power.

Read more: Sony ECM-W5 Announced | Sony DWX Gen 4 Announced

The shrinking UHF band and the World Radio Conference

(46:06 in the episode)

Since 2012, the 800 MHz and then the 700 MHz bands went to LTE and 5G – “the spectrum follows the money”, as Markus puts it – leaving radio mics with nearly half the space while channel counts keep rising. Exhibitors at large shows in Munich can run 38 to 100 channels per booth, and Markus says the German military has started using UHF at far higher power, with one test near Munich knocking out radio mics in the area. Older kits from around 2010 can also land in today’s 5G frequencies, causing dropouts near mobile masts: check the sticker on the back.

Decisions on all of this are made at the ITU’s World Radio Conference. Markus expects 470–694 MHz to remain usable until 2031, though shared with other users, and recommends that range for anyone buying UHF now. What happens after that, nobody knows – and that uncertainty, he says, is what holds back development.

Travelling with wireless kits

(01:03:44 in the episode)

There is no worldwide travel band. Officially, a CE-certified UHF kit is not legal in the US without FCC certification, and even 2.4 GHz allocations differ between regions. Markus names China and Japan as the most complicated destinations; the officially correct route is to rent or buy on location.

In practice, Markus says he has never heard of a private user being fined for using their own system abroad – with one firm exception: do not switch on a radio mic in Israel unless it is licensed there.

32-bit float: what’s real, what it fixes and what it doesn’t

(01:10:57 in the episode)

On the ECM-W5, 32-bit float is generated in the transmitter using two stacked A/D converters and sent digitally through the Multi Interface Shoe into compatible cameras, with up to four channels and a 64 GB backup on each transmitter. Markus stresses that he is going by Sony’s internal presentation and has not used the W5 himself yet. Because every available A/D converter is 24-bit, he is sceptical of systems that became “32-bit float” via a firmware update.

What 32-bit float does not fix: a clipping capsule or analogue input stage, clothing rustle or cable noise. And there is a trap – adjust the level in post and hit save, and the file is no longer 32-bit float. Like a raw photo, always work on a copy and archive the original.

Common mistakes, lav placement and the next big step

(01:17:02 in the episode)

The most common mistakes Markus sees: not learning how to scan the spectrum, trusting that last week’s frequency still works, flat batteries and lav connectors that are plugged in but not screwed down. His advice is to practise with your kit under pressure, not just on the kitchen table, and to always carry a spare – even an on-camera shotgun beats no audio. For hiding lavs, Nino points to MZed’s 86-hour Cinema Sound course by Mark Edward Lewis.

As for the next big change, Markus does not expect a leap until regulators decide on the spectrum. He expects better spectrum efficiency, smaller transmitters, timecode and 32-bit float backup moving into high-end systems – and he would love to see affordable wireless in-ear monitoring.

Read more: Cinema Sound on MZed | Markus Warlich on YouTube

Do you use 2.4 GHz, UHF, or both on your shoots – and would you like more long-form interviews like this, or keep Focus Check strictly weekly news? Let us know in the comments below or on YouTube, email us at [email protected], and subscribe to Focus Check on your favourite podcast platform.