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DJI wireless mics


kevcarlson
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Hello,

I wasn't able to find this topic so I thought I'd ask.

I am not a beginner by any means, but I'd love input from true experts.  I'd like to understand pros and cons to using traditional wireless (like sennheiser G4 level) and these new DJI wireless mics.  I'd use the same b6 lavs.  Why would I go the sennheiser route?  

It seems like a dumb question, but it seems like the 2.4 G digital signal might be cleaner and less noise than analog, and maybe less interference?  I'm not usually in a congested area, and just doing interviews.  I'm just wondering if it's one of those things that takes time for a whole industry to come around to change to what might be a better solution?

I totally get that build quality will be cheaper etc.  but I am mostly just concerned with audio quality and performance.  

Thoughts?

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Anecdotal but I'm counting 18 2.4ghz wifi signals fighting each other for frequencies at my house in a single family neighborhood that is less dense than Los Angeles by far.  With something like a Sennheiser G4, you'd be able to choose a UHF band like their AW+ block (the recommended frequencies that are available for SoCal, your mileage might vary elsewhere) and will be able to dial into an actually unused frequency.  Being that it is the UHF band, you'll also to be able to choose an actually unused frequency whereas in 2.4ghz, it might be unused for a minute or two and then a WiFi router decides to auto switch to that frequency to fight you on it.  Leave the 2.4ghz stuff to the "vloggers".

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Consumer-ish 2.4GHz solutions like the DJI Mic and the Rode Wireless GO II offer a clever feature: built-in recording.  So even if there is wireless interference you still have a clean recording saved to the transmitter as a backup.  You'll just have to transfer the files and do some additional editing afterwards.

 

I've watched tons of Youtube reviews of these devices and dropouts can occur when they are hundreds of feet away.  But at "normal" distances like interviews there shouldn't be a problem. Yes... the 2.4GHz band is congested... but these modern devices use various methods of frequency-hopping to mitigate interference.

 

There are not "professional" devices but they could get the job done.

 

My biggest question is if these consumer solutions can power the B6 microphone.  I'm not sure if they provide the proper plug-in power for professional mics.  That could be a problem.  But I don't know.

 

I'd suggest renting the DJI or Rode from a place like LensRentals and try them for yourself.  Each is available for $31 a week.

 

Or for that matter... you can rent a G4 for $54/week and see how it works too.

 

😎

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Not really reliable and some kind of unpredictable for serious work, as Codyman mentioned.

It may run very well in the one moment and in the other there's a dropout produced by some random mobile device around. Very bad too: wireless video, wireless focus and wireless DMX controlled lighting units (worse!!).

But: I've been using 2,4 Ghz audio devices for any purpose which are not important for the product, e.g. camera return.

That makes sense in my opinion since it doesn't steal me UHF frequencies neither produce intermodulations harming my mikes and hops.

I have no experience though with DJI, but with "China-no-name", Rode, Sennheiser and Deity. Deity is most reliable by far, but that is achieved by too much delay.

 

 

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15 hours ago, Michael Scrip said:

Consumer-ish 2.4GHz solutions like the DJI Mic and the Rode Wireless GO II offer a clever feature: built-in recording.  So even if there is wireless interference you still have a clean recording saved to the transmitter as a backup.  You'll just have to transfer the files and do some additional editing afterwards.

 

I

How did they dodge the Zaxcom patent?

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1 hour ago, Ty Ford said:

How did they dodge the Zaxcom patent?

I think possibly Zaxcom felt that these products are so far out of the professional arena that it wasn't worth the time and expense to defend the patent regarding these specific devices. I may not be correct on this but it is quite possible that is how they "dodged" having a legal patent dispute. It could as well relate to whether these devices have smite timecode or not, etc., etc.

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1 hour ago, Jeff Wexler said:

I think possibly Zaxcom felt that these products are so far out of the professional arena that it wasn't worth the time and expense to defend the patent regarding these specific devices. I may not be correct on this but it is quite possible that is how they "dodged" having a legal patent dispute. It could as well relate to whether these devices have smite timecode or not, etc., etc.

 

Apparently there was a licensing agreement between Zax and Deity, maybe/probably agreed for the reasons Jeff states. So I'll guess some money for Zaxcom, lower legal hassles for both companies. There are probably press releases floating around announcing the agreement, but here's a web story that appears to have things straight, at least from the Deity POV (no dis; Andrew Jones of Deity is quoted. I don't see quotes from Glenn and his team).

 

Deity & Zaxcom Sign Patent Agreement Giving the BP-TRX Ability to Transmit & Record Audio Simultaneously

 

IIRC, Glenn said here that Zaxcom reached out to Rode about a license for their system. I don't know if they reached an agreement. I kinda don't care. No vitriol; I just have other things to do. 

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Well the Zaxcom patents expire in 2025 so I'm sure it will be open season then and I'd imagine manufacturers that have these features overseas but not here could just firmware unlock things at that point.

 

Per Zaxcom's own website (https://zaxcom.com/company/patents/) these are the Patents that were licensed to Deity and they expire summer 2025.

 

https://patents.google.com/patent/US9336307B2/en?oq=9336307

https://patents.google.com/patent/US8385814B2/en?oq=8385814

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Simple answer: No. As said by others, you may find a 2.4ghz wireless that performs quite well in some situations but is totally useless in other situations, environments, and even sometimes in the same environment on the same day. So, you could use these low cost 2.4ghz devices if you have to but you will get royally burned at some point and it could cost you your job.

37 minutes ago, BAB414 said:

Don't all the new high end digital wireless mics operate in the 2.4 GHz range?

None of the high end digital wireless operate in the 2.4 ghz range.

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Kevcarlson, here is some information that may help clarify why UHF is professional and 2.4G is amateur:

 

UHF operates in the same frequencies as broadcast television. That spectrum is regulated and carefully administered by the FCC (and similar regulating bodies around the world). It is reserved for only two purposes; broadcasting a TV channel and, on the unused channels, wireless microphones.  Nothing else operates in these bands. One has to have brilliant RF engineers on staff to design UHF radios. The power of transmitters is regulated.

 

2.4G is an un-regulated band. It is completely open to use and abuse by anyone for any reason. Some of the products operating in 2.4G are Cordless phones, baby monitors, Bluetooth, Wi-Fi, Garage door openers, Zigbee, wireless speakers, car alarms, some forms of radar, and smart power meters. A device can transmit up to one watt and blow out every other device in this band and it is legal (as far as I can tell). 

 

The reason it all works is because of complex spread-spectrum modulation, which has lot's of error correction, but at the cost of delay in transmission.

 

The reason it is so popular is that 1: it's unregulated so anyone can use it. 2: the complex RF design is done by chip manufacturers who have figured out all the complex stuff for product developers so they can buy a chip and away they go.

 

The problem - at any given location, you don't know how much junk is being broadcast on 2.4G. Results are unpredictable. UHF is no panacea as it can have the problem of being crowded by lots of wireless microphones in some dense metro areas.

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What are your thoughts on the Sennheiser AVX system?  It uses the 1.9 GHz band.  I don't think there are many things that use that band.

 

I've also seen some Shure mics that use the 900 MHz band.  That frequency used to be for old cordless phones... but I don't think there are many things using that band either.

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4 hours ago, Michael Scrip said:

I've also seen some Shure mics that use the 900 MHz band.  That frequency used to be for old cordless phones... but I don't think there are many things using that band either.

Lectrosonics as well offers a few products using frequencies within the 900MHz band. (probably some other brands too, I think maybe Audio Ltd & Wisycom? )

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18 hours ago, Michael Scrip said:

I've also seen some Shure mics that use the 900 MHz band.  That frequency used to be for old cordless phones... but I don't think there are many things using that band either.

 

Wireless microphone operators with a Part 74 license are allowed to use 941–960MHz, except for a few frequencies reserved for other uses.  Some frequencies may be permitted only when coordinating with local FAA officials.  Unlicensed use is not authorized, so any products in these bands are targeted toward professional users eligible for licensing.

 

In contrast, I believe the old cordless phones operated on an unlicensed basis in the 900-928 MHz range.

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2 minutes ago, Matthew Steel said:

 

Wireless microphone operators with a Part 74 license are allowed to use 941–960MHz, except for a few frequencies reserved for other uses.  Some frequencies may be permitted only when coordinating with local FAA officials.  Unlicensed use is not authorized, so any products in these bands are targeted toward professional users eligible for licensing.

 

In contrast, I believe the old cordless phones operated on an unlicensed basis in the 900-928 MHz range.

Yeah you need a license fo rthe 941-960 stuff.  Although the IST 902-928 stuff in the US is open season I believe.  This is Sound Devices chart for their "spectraband" transmitter which seems to tune into anything and everything legal out there (in the US).

image.png

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  • 3 months later...
On 9/15/2022 at 10:00 AM, kevcarlson said:

Great info--thank you to everyone that contributed to the conversation.  I am certainly lacking in my radio band knowledge, and so the explanations were very helpful.

Sounds like the 2.4 mics can be a good tool to have available, but are certainly not the way of the future at this point.  

My conclusion as well. Have had nothing but good success with them. With backup internal recording and paired with a sound lav, I almost feel as if I robbed a bank when in post. Dji has decidedly challenged easy conventions such as “pro” and “prosumer” IMHO.

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On 9/15/2022 at 12:00 PM, kevcarlson said:

Great info--thank you to everyone that contributed to the conversation.  I am certainly lacking in my radio band knowledge, and so the explanations were very helpful.

Sounds like the 2.4 mics can be a good tool to have available, but are certainly not the way of the future at this point.  

 

I think you missed part of the conversation.

I am being snobbish and I apologize. I only do News.

I would feel like a piker if I ever even thought of using the G4 stuff.

 

If you are serious, you will quickly be replacing your G4 pro-sumer wireless or 2.4 gig amateur stuff, should you purchase either. If, perhaps, it works for you...you might be known as a pioneer.

 

 

Cheers,

Tim

 

*I'm smiling to myself at the prospect of ending the year on an uncharacteristic gruff note!

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If the DJI who makes wireless mics is the same DJI that makes drones then in using them you are opening you and your audio to being listened to by the Chinese government.  They may not care about what your talent says, but I'd bet they left themselves a back door to listen if they want to.   Re: AVX: Luke Seerveld, a gaffer who does the very excellent and long running "Meet The Gaffer" blog series does all his interviews with AVX.   He is very careful and his audio sounds just fine.  All short range and generally non-time-critical, a perfect application for that technology.  His shoots are not like pro location dialog recording jobs, to say the least, and he has told me that he would not recommend the AVX for what we do.

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46 minutes ago, Philip Perkins said:

If the DJI who makes wireless mics is the same DJI that makes drones then in using them you are opening you and your audio to being listened to by the Chinese government.


Citation needed.  If you have evidence of this (and a technical explanation for how they eavesdrop on a non-internet connected device), please share!

I'm not saying it's impossible or it's not a concern, I'm just saying I'd like my surveillance paranoia to be evidence-based.  We already live in a world where the US government & the Five Eyes has access to virtually everything with an internet connection, and I'm sure the Chinese government has similar capabilities.  I'm not sure why making a special engineering effort to compromise a relatively niche device like a wireless mic would be worth their while when they have so much better access elsewhere.

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