gotty Posted October 25, 2015 Share Posted October 25, 2015 The school I help with currently has 4 Trantec S4.4 UHF radio mics which work superbly well, and have a good range (receivers half way up the hall, they work beyond the stage through 3 steel-framed brick walls!) But there's a chance they will want a couple more next month (they don't need to work through brick walls - just the 50ft to the back of the stage) I'm contemplating buying a couple of 2.4GHz radio mics for another application where interference is not an issue, and would use these. However, I'm concerned about interference in the hall. The school is very remote, so there's no chance of multiple neighbouring RF interference sources, but it does have WiFi in the hall. Does anyone have experience of using 2.4GHz mics? If so, what is the likelihood of interference from a hall full of 300+, with their phones trying to connect to the WiFi? Of course, we could always turn the WiFi off. Link to comment Share on other sites More sharing options...
ojc123 Posted October 25, 2015 Share Posted October 25, 2015 I've got some Audio Technica ATW-1101 and they've not had any problems at all. Link to comment Share on other sites More sharing options...
bruce Posted October 25, 2015 Share Posted October 25, 2015 Of course, we could always turn the WiFi off. You might be able to turn off the installed access points, but you wouldn’t be able to turn off the potentially several hundred devices in the pockets of the audience. Link to comment Share on other sites More sharing options...
paulears Posted October 25, 2015 Share Posted October 25, 2015 I use them in a theatre with 1400 capacity. They have worked flawlessly apart from one occasion when somebody accidentally put a wireless hub on top of the rack which killed them stone dead. In practice, the wireless mics cause more interference to the wireless network, with people on stage complaining they can't connect. The mics didn't miss a beat. I've bought more since I had them. I like them a lot. Link to comment Share on other sites More sharing options...
gotty Posted October 25, 2015 Author Share Posted October 25, 2015 I've got some Audio Technica ATW-1101 and they've not had any problems at all. The mics didn't miss a beat. I've bought more since I had them. I like them a lot. Really good news - thanks both - very much appreciated. You might be able to turn off the installed access points, but you wouldn't be able to turn off the potentially several hundred devices in the pockets of the audience. I'm told (but can't verify) that mobile phones won't transmit a WiFi signal in the absence of a detected WAP. Also, we'd be unable to log in and access the wireless network on the laptop with a hall full of phones - but we have no problems. So I think we should be okay on that score. Thanks for the thoughts. Link to comment Share on other sites More sharing options...
peza2010 Posted October 26, 2015 Share Posted October 26, 2015 Ive used line 6's 2.4ghz offering a fair bit.The version I used had a switch on the rack, which changed between a "play nice with wifi" and a "crush everything else" switch. Im not sure what that switch does in terms of the technology behind it, but it got us out of a couple of scrapes. Link to comment Share on other sites More sharing options...
richard_cooper Posted October 26, 2015 Share Posted October 26, 2015 I had a rack of 8 Line6 for a few years, and only ever had one issue, other than physical breakage of packs and hand helds. That was when a someone attempting to control 50 odd kids placed a box containing their 50+ switched on mobile phones on top of the rack, and even then it was just a bit of odd high frequency noise on a couple of channels, which could have been interference on the audio side. These were an older model that only has Peza's "crush everything"mode. Link to comment Share on other sites More sharing options...
Stuart91 Posted October 26, 2015 Share Posted October 26, 2015 In practice, the wireless mics cause more interference to the wireless network, with people on stage complaining they can't connect. The mics didn't miss a beat. This can sometimes be a downside if you have to "play nicely" with others. A while back I got a last-minute rental for a rack of four UHF systems - the only requirements given were "Anything except 2.4GHz and it has to be here within half an hour". It turned out that the audio provider had some Line 6 systems which were wiping out an audience voting system. The radio mics couldn't co-exist with it - if they were on low power, they wouldn't work, and on high power they wiped it out. With 2.4Ghz band being used for more and more things, the chances of disrupting something increase. And of course, when it happens, it'll be deemed to be the fault of the person with the equipment causing the interference. I'm told (but can't verify) that mobile phones won't transmit a WiFi signal in the absence of a detected WAP. How do the phones discover whether a WAP is present or not? They'll have to transmit to detect it. This might be less disruptive than continual data transmission, but I wonder how regularly they check, and what strength of signal is used. Link to comment Share on other sites More sharing options...
richard_cooper Posted October 26, 2015 Share Posted October 26, 2015 This can sometimes be a downside if you have to "play nicely" with others. A while back I got a last-minute rental for a rack of four UHF systems - the only requirements given were "Anything except 2.4GHz and it has to be here within half an hour". It turned out that the audio provider had some Line 6 systems which were wiping out an audience voting system. The radio mics couldn't co-exist with it - if they were on low power, they wouldn't work, and on high power they wiped it out. With 2.4Ghz band being used for more and more things, the chances of disrupting something increase. And of course, when it happens, it'll be deemed to be the fault of the person with the equipment causing the interference. Absolutely agree. The Line6s were fantastic tools within the selection we had. They were owned by the venue and only used in that venue. They could wipe out 2.4Ghz wifi, so we used 5GHz for production kit. Our RC4Magic wireless DMX system seemed to be completely unaffected by the mics however. We usually had no need for access to general purpose wifi during shows, and on the occasions we did, we just used ch38 mics. Where you control the spectrum use they can be incredibly useful license free additions to the toolkit, but need to be co-ordinated with other users. The problem with 2.4GHz is that nobody considers co-ordinating between users on an event as it's seen as "free". Link to comment Share on other sites More sharing options...
bruce Posted October 26, 2015 Share Posted October 26, 2015 How do the phones discover whether a WAP is present or not? They'll have to transmit to detect it. This might be less disruptive than continual data transmission, but I wonder how regularly they check, and what strength of signal is used. Actually, in an infrastructure network, clients don’t have to transmit to check - they just listen/scan for beacon frames, which the access points use to announce their presence. But every phone has the potential to behave as an access point.... Link to comment Share on other sites More sharing options...
OddSocks Posted October 27, 2015 Share Posted October 27, 2015 How well do these 2.4Ghz mics cope with line of sight,as I have played with a 2.4Ghz radio control system and almost anything between transmitter and receiver meant a lost signal. Link to comment Share on other sites More sharing options...
Shez Posted October 27, 2015 Share Posted October 27, 2015 Much like other radio systems, it really depends on how good it is. A well designed (expensive) one is likely to perform better than a cheap one. I've been using the Line6 systems for a few years now - not 100% trouble free (is any radio system?!) but nonetheless very good. In RF1 mode, it uses four separate frequencies which is very robust and has no problem with a wall in the way. That's the mode that doesn't play nicely with WiFi though. I've heard of other 2.4G systems struggling with obstructions so as I say, it depends. In general, the higher the frequency, the more important line of sight becomes so they won't generally perform as well in that regard as UHF. Link to comment Share on other sites More sharing options...
alistermorton Posted October 27, 2015 Share Posted October 27, 2015 Although not a mic system, we've found the RC4 radio dimmers, which also work on 2.4GHz, are very tolerant of obstructions such as walls and a bit building steelwork for exmaple. So, as Shez says, it depends on how well designed the system is. Hint : RC4 dimmers aren't cheap (although IMO they aren't expensive for what they are). Link to comment Share on other sites More sharing options...
gotty Posted October 28, 2015 Author Share Posted October 28, 2015 How do the phones discover whether a WAP is present or not? They'll have to transmit to detect it. This might be less disruptive than continual data transmission, but I wonder how regularly they check, and what strength of signal is used.WAPs transmit a regular beacon (which includes its SSID) and wireless devices can listen for about a tenth of a second to each channel in turn listening for a beacon. Only when one is picked up will the device transmit. I've looked more deeply into this, and there is an "active scan" mode where devices do transmit a very short request frame, and then wait about 20ms for a response before moving on to the next channel. Statistically, the odds of even a small number of devices transmitting the request frame at the same time are minuscule. It is theoretically possible for devices to act as access points, but I can't imagine too many of these. And, of course, it's also spread-spectrum, which should also reduce the chances of interference. So, in theory, there shouldn't be much interference - which seems to be supported by some of the comments here. the more important line of sight becomes so they won't generally perform as well in that regard as UHF. Indeed. Fortunately, in our case, we will be working line-of-sight all the time. Thanks for the comments.I'm going to borrow a mic, and armed with as many wifi devices as we can muster, we're going to experiment. Link to comment Share on other sites More sharing options...
bruce Posted October 28, 2015 Share Posted October 28, 2015 It is theoretically possible for devices to act as access points, but I can't imagine too many of these. And, of course, it's also spread-spectrum, which should also reduce the chances of interference. It’s more than theoretically possible :) Take your iPhone. Click “settings”. Click “Personal hotspot”. Et voila.... Coming home on the train tonight - not at rush hour, so fairly quiet - I could detect half a dozen within the carriage. Link to comment Share on other sites More sharing options...
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