BatchFile Posted November 21, 2011 Share Posted November 21, 2011 I'd love to put som permenant comms in to the school hall, but the ubiquitous Canford / Tecpro solution, despite being EXACTLY what we want, is prohibitively expensive. Has anyone got any suggestions for similar, but cheaper, systems? We could probably live without the "call" function, as long as we can have voice. Many thanks in advance! Link to comment Share on other sites More sharing options...
themadhippy Posted November 21, 2011 Share Posted November 21, 2011 2 old telephone handsets (the type with carbon michrophones) and a 12v battery. Link to comment Share on other sites More sharing options...
pjb304 Posted November 21, 2011 Share Posted November 21, 2011 One option if you've got a good electronics department would be to make your own using the schematics from comclone, which I believe is compatible with Clearcom systems. We looked into this but then discovered that it is possible to buy refurbished units from canford and went for that route, due to lack of available time to make our own. Link to comment Share on other sites More sharing options...
boatman Posted November 21, 2011 Share Posted November 21, 2011 This thread and in particular this post in another thread show that Comclone isn't the easiest of boxes to get working. This system might be closer to your needs. Link to comment Share on other sites More sharing options...
pjb304 Posted November 21, 2011 Share Posted November 21, 2011 I wasn't aware of the problems with the com clone system, now knowing that it's a shame we weren't able to put the time aside to work with them. Asa few of us are members of the Electronics and Computer Science department so would have been able to ask experts to help. Link to comment Share on other sites More sharing options...
dbuckley Posted November 21, 2011 Share Posted November 21, 2011 One of the key features of a decent comms system is the ability not to deafen ones self with one's own voice, which requires that the intercom has adjustable sidetone. TO make this work then the intercom typically has to have a "hybrid" block, which essentially converts the duplex party line to individual lines for sending a receiving. The ComClone2 schematic certainly seems to have such componentary. Link to comment Share on other sites More sharing options...
timsabre Posted November 21, 2011 Share Posted November 21, 2011 I've built some of the comclone2 packs and they worked fine with cheapo PC headsets. I had to reduce the gain of the power amp stage. Link to comment Share on other sites More sharing options...
TomHoward Posted November 21, 2011 Share Posted November 21, 2011 We've got the ASL Comms, which are not quite as expensive at the Canford units, but still seem very expensive for what they are. Link to comment Share on other sites More sharing options...
timd Posted November 22, 2011 Share Posted November 22, 2011 One of the key features of a decent comms system is the ability not to deafen ones self with one's own voice, which requires that the intercom has adjustable sidetone. TO make this work then the intercom typically has to have a "hybrid" block, which essentially converts the duplex party line to individual lines for sending a receiving. The ComClone2 schematic certainly seems to have such componentary. Could you not just set the button up to drop the gain on your preamp while you're talking? Tim Link to comment Share on other sites More sharing options...
dbuckley Posted November 22, 2011 Share Posted November 22, 2011 Could you not just set the button up to drop the gain on your preamp while you're talking?'Course you could. It's just that sometimes I have my hands full, or have to speak at a moments notice, or every now and again, have to speak urgently with both my hands occupied. The beauty of a good comms system is that it's almost invisible, you just communicate using it. Link to comment Share on other sites More sharing options...
BatchFile Posted November 22, 2011 Author Share Posted November 22, 2011 Just been looking at the ASL stuff which looks nice - but, like Canford / Tecpro, overpriced by a factor of at least 10 - given the simplicity of what's needed, I can't believe that there's nobody in China knocking out systems like @boatman suggested above for £30 or less - you can get a mobile phone for that and the circuitry in those is whaaaaay more complex than what's needed here! Unfortunately we're a small secondary school and I don't think we'll be in a position to knock any up ourselves as the electronics dept doesn't exist and the guy that teaches it also teaches a load of other stuff - though there is a part time technician I could ask... Link to comment Share on other sites More sharing options...
PeterT Posted November 22, 2011 Share Posted November 22, 2011 The problem with cheap knock-off Chinese stuff is one of reliability. you really don't want your headset system to fail at a critical moment. That's what you're paying for with the Canford/ Clearcom/ Altair systems. If you want a cheap and easy system I'd also second what Hippy said above, get a couple of Army surplus field telephones. They simply require a two core cable to work and run off batteries and you can get them on Ebay for very little. Link to comment Share on other sites More sharing options...
BatchFile Posted November 22, 2011 Author Share Posted November 22, 2011 If you want a cheap and easy system I'd also second what Hippy said above, get a couple of Army surplus field telephones. They simply require a two core cable to work and run off batteries and you can get them on Ebay for very little. Thinking coordinating holding a phone and a followspot may be beyond my operators :( I agree with what you say about the chinese knock off stuff too; if this was a pro theatre with shows every week I wouldn't bat an eyelid, but for the 3 or 4 times a year we'd use it I can't justify £220+ per beltpack so need a similar but (80-90%) cheaper option - and I'm struggling to find any... Link to comment Share on other sites More sharing options...
timsabre Posted November 22, 2011 Share Posted November 22, 2011 Just been looking at the ASL stuff which looks nice - but, like Canford / Tecpro, overpriced by a factor of at least 10 - given the simplicity of what's needed, I can't believe that there's nobody in China knocking out systems like @boatman suggested above for £30 or less - you can get a mobile phone for that and the circuitry in those is whaaaaay more complex than what's needed here! It's all about quantities... mobile phones are made in the millions, so the manufacturing costs are driven right down. Most people get a new one every year. Comms systems last for years, probably only a few thousand are sold globally each year. This makes the manufacturing more costly. I design electronics for a living and I have lost count of the times people come to me expecting a full custom design to cost £50 because they can buy a DVD player in Tesco for £20, and their design is much simpler than that. Link to comment Share on other sites More sharing options...
GridGirl Posted November 22, 2011 Share Posted November 22, 2011 Thinking coordinating holding a phone and a followspot may be beyond my operators :( Get headsets - they exist! Sitting in my parents' garage is a 9-channel dimmer and desk which Dad built - it has a telephone circuit built into it and he has two old-style phone headsets which work perfectly well. Link to comment Share on other sites More sharing options...
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