iamchristuffin Posted June 19, 2007 Share Posted June 19, 2007 My school has a TecPro comms system, but my SM wants a wireless headset so that he can stay 'on cans' during scene changes, moving around the wings, etc. Whats the best way to do this? It need to be relatively cheap, as he's going to buy it himself The best way I can think of, though quite expensive, was to buy a Sennheiser wireless microphone and receiver, and a wireless receiver and transmitter, and connect these into the 'ring' I'm not even sure if this would work anyway. Can anyone point me in the right direction? Thanks Link to comment Share on other sites More sharing options...
cedd Posted June 19, 2007 Share Posted June 19, 2007 Hi Chris The pin protocal on a comms system is rather strange. There is the power supply +ve and a ground, so that's two pins. Then the audio is on a "bus" on the third pin. Beltpacks add and take audio from it in the simplest of terms. But.... This pin also carries your call lamp pulse (DC so it's prevented from reaching the audio circuit with a capacitor, very similair to phantom power only it's not there all the time). I have a feeling you'd need to isolate this from whatever wireless front end you stick on it. The other thing to think about is sidetone. As you can imagine if every belt pack is taking audio off of the bus regardless, if a beltpack adds audio to the bus (the user speaks) it will imediately also take that audio from the bus and put it back into the headphones. Sidetone is useful as a confidence check to be sure you've "gone to air", however it also requires fancy switching to enable it to be adjusted in volume so other parties can be heard. This is done by inverting either the outgoing or incoming signal and laying them on top of each other. This cancels or "nulls" when the two are equal. Adjusting the amount of the inverting input to the point that they mix will change the amount of sidetone. This too will be an issue if the user wants to hear what others are saying on the "party line" while their mic is open. In short, adding to and taking from the bus is hard work. What I'd be more tempted to do is use an existing beltpack and at the headphone socket (I'm guessing 5 pin XLR) tap off the headphone signal. Pot it down to a line level and feed it into your transmitter. At the same time take your mic reciever output and put this onto the mic pair, ensuring the two are at the same level. This means all the clever stuff is done within the factory-built and approved beltpack and all your additions happen after this.A quick bodge with a beltpack reciever and transmitter into one headet should be do-able, though proximity of the two units may be a problem. I know when I place my In ear Monitor reciever too near my radio mic belt pack, I get squelch lift and interference. Worth a shot though! Link to comment Share on other sites More sharing options...
bruce Posted June 19, 2007 Share Posted June 19, 2007 Whats the best way to do this?With a proper set of wireless cans. more info hereIt need to be relatively cheap, as he's going to buy it himself Ah. The best way and the cheap way tend to be mutually exclusive.... Link to comment Share on other sites More sharing options...
Light Console Posted June 19, 2007 Share Posted June 19, 2007 When we did this recently, using a method just like cedd, we realised to get full 2 way cans, the wireless people had to have two radios, one rx and the other tx. The other way I have achieved wireless comms is to set up a normal outstation, and attach the headphone to the mic of a radio system, set to VOX, and vice versa. This enabled a normal system, but the wireless people had to PTT! Or something, sorry, it has been a long day! Link to comment Share on other sites More sharing options...
bruce Posted June 19, 2007 Share Posted June 19, 2007 Random thought: what sort of wireless headset system do they use at a drive-through McDonalds. Might it be adaptable? A wireless tecpro set is (from memory) about 1400 pounds. I can't see the McDonald's version costing that.... Link to comment Share on other sites More sharing options...
slipstream Posted June 19, 2007 Share Posted June 19, 2007 Most of them are IR as far as I remember, bit limiting for behind flats n legs Link to comment Share on other sites More sharing options...
Seano Posted June 20, 2007 Share Posted June 20, 2007 Most of them are IR as far as I rememberMany years ago now, I used to service the wretched things. The sound company I worked for sporadically had the contract to install them in the first generation of UK drive-throughs. (I thought they'd never catch on over here, shows what I know.) They were IR then, made by an american company called HME. That early model was pretty clunky, but had surprisingly good coverage. I can only imagine its improved in the years since. None of which is any help to the op whatsover, I'm afraid. Seanx Link to comment Share on other sites More sharing options...
GridGirl Posted June 20, 2007 Share Posted June 20, 2007 I've seen a normal TecPro beltpack plugged into a cordless phone handset, with the cordless phone base station plugged into the cans ring. I have no idea of the electronics involved, or how it was built, but I believe it worked pretty well provided you didn't get out of range of the base station. Link to comment Share on other sites More sharing options...
Neil Hampson Posted June 21, 2007 Share Posted June 21, 2007 I'm not sure on the cost, but there is a middle ground available from Canford, A 2 way Radio interface, the unit basically transmitts anything that is said on cans to PMR radios, and then the PPT on a radio will open the Party line to the rest of the comms system. obviously the radios are not full duplex, i.e. if a radio is recieving it can't transmit and vice versa. The early versions used the call button as a PPT for the Ring, anyone wanting to speak to the radio had to push the call button and hold it before it would transmit to the radios. the rest of the comms ring behaved as normal. I'm sure that this option was much cheaper than the all out wireless comms pack Link to comment Share on other sites More sharing options...
paulears Posted June 21, 2007 Share Posted June 21, 2007 Much cheaper and pretty horrible to use. The cheapest method of having a working system is a wireless tx and receiver, as detailed higher up. I've got a Trantec I use for this purpose on bigger shows. I need to hear what's going on, and a receiver works really well - usually well enough to be able to wander FOH and still hear the comms. If you need to be able to talk wirelessly an awful lot, then the only proper system is a real duplex, single box system and they are expensive. The other option of having a normal lav pack and feeding the reciever output back into a normal belt pack works ok - if you can arranged some frequency separation, not always easy. Of course you could press and older VHF channel into use and this is ok. The cheapest solution for only occasional talk back, is to use Chinese higher spec PMR446 two way radios to get the remote audio back into the comms system. Make sure you use ctcss, or even better dts encoding to prevent unwanted stuff getting into the comms system and wrecking it. I do this from time to time and for my style of work it's ok. Very often the comms circuit would simply carry stuff like "Paul, can you come Stage Left, somebodies fell over" and one of the other people with cans on who could see me raise a hand would simply say "he's on his way" - other times, I'd dig the walkie talkie out and say "the downstage left pyro will not fire - a twirly just kicked the plug out!". If I was playing a very active role and had to talk a lot, then I like the security of a real system, but the wireless versions can made to work. Link to comment Share on other sites More sharing options...
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