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Radio (wireless) link for remote speaker stacks


Keith_
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Hi Folks,

I'm new to this forum, an amateur, having started in live sound 40 years ago and returned to it in what is for me an alien digital world.

Currently, I am looking into linking up a pair of remote speaker stacks that will be 100m to 200m away from the main (with delays of course).

I have seen others use radio mic frequency links with shark (log periodic) antennas for this, but it seems a very expensive way to go about it.

I am wondering about using an ethernet over radio at 5GHz, but I am not sure how I would get audio into and out of the ethernet (though I guess it is the same technology as 'smart speakers' in the home).

I prefer licence free and reasonably secure (we don't want the punters breaking in on the channel).

Suggestions sought.

Many thanks,

 

Keith.

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Ethernet will have unacceptable latency (delay) for your application and could well end up with complications such as packet loss if not done right.

Stick to the radio mic/IEM option. Fit for purpose and proven solution.

Edited by paulears
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Ethernet will have unacceptable latency (delay) for your application and could well end up with complications such as packet loss if not done right.

Stick to the radio mic/IEM option. Fit for purpose and proven solution.

 

 

 

Good luck to anyone trying to send radio mic/IEM over 100/200m as in practical terms it probably just won't work unless you have specialist kit and even then it will not be a robust link.

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Ethernet will have unacceptable latency (delay) for your application and could well end up with complications such as packet loss if not done right.

Stick to the radio mic/IEM option. Fit for purpose and proven solution.

 

 

 

Good luck to anyone trying to send radio mic/IEM over 100/200m as in practical terms it probably just won't work unless you have specialist kit and even then it will not be a robust link.

 

I stand behind my recommendation that at least for 100m and likely for 200m line of sight, a suitable iem transmitter with a directional antenna paddle and a receiver with a suitable paddle will deliver reliable results.

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We have done a PA event for many years which started as one big system with around 26 horn speakers, primarily for public safety.

 

As the event has progresses it has broken into 4 zones and a fifth added, we now have 3 distinct entertainment zones which work indenendantly when required but relay the 'main' system the rest of the time.

 

 

For 4 years we used an analogue Band 1 audio link [as used between radio studio and remote transmitter site] which works extrememly well but it was breaking into the sites existing services.

 

Most is now fairly simply tapped off the 100V line of the 'main' with long runs of speaker cable through trees and over buildings etc, But one of the systems is battery operated & out on its own with no sensible cable route for a link

There is 150m line of sight between the 2 systems but restricted by buildings and trees so TX & RX aerials have to be fairly accurately positioned at about 3m high max. For 2 years we tried IEM with paddles which worked perfectly until the public entered, then it got very shakey.

 

During the second year we experimented with these: https://cpc.farnell.com/denon-professional/dn-202wt/wireless-audio-transmitter/dp/DP34659?st=audio%20transmitter Which I believe are electrically similar to Garys suggestion. They are listed as 30m range and with them mounted at 3m [the same as IEMS] we get solid signals up to 120m at which point it stops dead, just like switching it off. move it back a couple of metres and it takes a couple of seconds to reconnect. We now ensure we position a speaker pole in the right place for the RX and run 60m of signal cable, positioning IEM paddles at the same position is not as reliable.

 

We have experimented in free open space with the Denon and the same thing happens everytime so we wonder if it's a timing issue rather than RF. Other than the range limit the product is very good and passes subaudible tones OK.

 

 

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I have seen others use radio mic frequency links with shark (log periodic) antennas for this, but it seems a very expensive way to go about it.

"Paddles" & the like can be exorbitant, but if you are prepared to experiment UHF TV aerials are cheap as chips.

 

I prefer licence free and reasonably secure (we don't want the punters breaking in on the channel).

Regrettably "licence-free" (whether VHF, UHF or 2.4GHz) & "reasonably secure" don't go well together once the public & side-shows are in. If mono was acceptable I would go with VHF radiomics, because it's what I know will work.However, Gary's & sunray's options do seem worth a punt.

Edited by sandall
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"Paddles" & the like can be exorbitant, but if you are prepared to experiment UHF TV aerials are cheap as chips.

 

Indeed and my paddles are exactly that, cut down TV aerials, sometimes with a replacement dipole. I also have wideband log periodic TV aerials.

Regrettably "licence-free" (whether VHF, UHF or 2.4GHz) & "reasonably secure" don't go well together once the public & side-shows are in.

I've found 2.4GHz has become unusable sometimes at large gatherings, also I'm starting to find organised groups are now using CH70 [think tourists on a coach trip or school outing]
If mono was acceptable I would go with VHF radiomics, because it's what I know will work.However,
Funny how people have different results, for years I would have agreed with you [maybe because I was using EDC kit] but gradually I changed my mind and I think it's fair to say my VHF kit hasn't been used for maybe 5 years. Also I find lots of telementary interference on VHF, especially in larger hotels and railway stations.

 

I forgot to add the delay in the Dennon units may be too long, on the system I described we can just hear the 'main' system when standing at the RX, if the wind is blowing the right way, and we hear the 'main' sound before it comes through the link.

Edited by sunray
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Ethernet will have unacceptable latency (delay) for your application

 

Will it?

 

Something like Cleanfeed (which wouldn’t’ be my first choice for an isolated network like this, but it does demonstrate the principle) would have an end to end latency of less than a quarter of a second - or about the same as an 80m audio path. So for something located 100-200m away, it’s probably not such a big issue.

 

And if you really want to drop the latency, there’s always Dante...

 

5GHz wifi, on band C, lightly licensed - kit is very cheap and if you use directional antenna the data link should be rock solid.

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Thanks folks, and you have been so quick in responding!

I rather like the idea of those little 2.4GHz boxes, boosted with directional yagi antennas. Should get much better range with say 16dB gain and a usable 30 degree beam that will help with isolation of the signal path. They are a simple solution, much better than digital wifi and much cheaper than radio mic type kit. Not sure between the KT and the Denon (the latter seems a bit more professional, but the KT has a 12V supply which is handy and anyway they might be the same thing under the case). I take sunray's point about 2.4GHz getting crowded, but with the directional antennas looking at each other, I hope it will be OK - am I right?

 

Thanks again,

 

Keith.

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Thanks folks, and you have been so quick in responding!

I rather like the idea of those little 2.4GHz boxes, boosted with directional yagi antennas. Should get much better range with say 16dB gain and a usable 30 degree beam that will help with isolation of the signal path. They are a simple solution, much better than digital wifi and much cheaper than radio mic type kit. Not sure between the KT and the Denon (the latter seems a bit more professional, but the KT has a 12V supply which is handy and anyway they might be the same thing under the case). I take sunray's point about 2.4GHz getting crowded, but with the directional antennas looking at each other, I hope it will be OK - am I right?

 

Thanks again,

 

Keith.

I've only used the Denon kit at one location and done tests at another so far I've not been aware of any significant dropouts but 2.4GHz radio mics at the same place vanished into the ether when the public arrived. Denon has a 12V supply also and RX will run on a 7AH battery for 3 days 0900 to 1700 without signs of flagging. I'm fairly convinced the aerials are fixed so some doctoring will be needed for yagis. I'll reiterate that they work well to about 120m and then stop, no dropouts, no warnings, no funny noises and moving closer by 2m they reconnect. It really is very predictable so I suspect it is not a signal strength issue.
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And if you really want to drop the latency, there’s always Dante...

 

Indeed, Mac Calder has previously explained how to make Dante operate in a wireless environment, something normally considered quite difficult, and Dante delivers very close to zero latency, and is frame accurate across the network, it doesn't get much better. And these days, once you've got the networking in place, dropping stereo audio in and out is actually fairly low cost. Still, getting "good enough" wireless networking is not cheap, any old WiFi is not going to cut the mustard...

 

Someone needs to commercialise Jack / JackTrip and put in a box with XLRs and an ethernet port.

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Yes, dbuckley, it seems Dante is the way to go for audio over ethernet (makes my Firewire mixer <Midas F32> seem old-fashioned). Unfortunately I found that (quoting Canford Audio, who quote Audinate)

 

Implementation - Wireless

'While possible in principle, the practical limitations of current wireless technology (802.11a/b/g/n) render reliable performance unachievable. For this reason DANTE software such as Virtual Sound card will not recognize wireless connections for audio data.'

 

I note that 802.11a/b/g/n includes 5.8GHz.

 

I looked into adding external Yagi to the bluetooth 2.4GHz kit mentioned above and it seems that might infringe UK Gov. regulations (my interpretation of quite complicated rules on the OFCOM website) - if the antenna is fixed on e.g. the Denon, that might be for a legal reason. Then I started looking at a 5.8GHz system (https://www.pcs-elec...38;currency=GBP) which operated in band-C, for which a licence is needed (£50/year) (Bruce's suggestion) but it seems solid pro-quality kit, the only thing is, that high up, even a wet tree might spoil the signal (antennas planned to be on little 4m towers).

 

My, how complicated this all is.

 

K.

Edited by Keith_
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Then I started looking at a 5.8GHz system (https://www.pcs-elec...38;currency=GBP) which operated in band-C, for which a licence is needed (£50/year) (Bruce's suggestion) but it seems solid pro-quality kit, the only thing is, that high up, even a wet tree might spoil the signal (antennas planned to be on little 4m towers).

 

 

I’m running a couple of 5.8GHz links across a city centre, using the cheap-as-chips Ubiquiti and Engenius kit. Longest link is about 2 miles, and one of the ends is behind a window. It’s been rock solid for several years. Im streaming audio over it, although in my application latency isn’t critical.

 

But +1 to Jon’s suggestion of a drum of cat5....

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