mrg198 Posted September 26, 2007 Share Posted September 26, 2007 Hi, I have 12 sets of Sennheiser EW300 G2 kit of which currently 8 sets are rack mounted in 2 x 4 way racks with an ADA and a 4 ch Behringer headphone amp (HA4700) which allows someone at the stage end with the rack to plug in a set of headphones and listen to the mic without needing to run up to the desk and listen there. The XLR sockets on the receivers are connected to a back panel with XLR sockets (male) on for the feed to the mixer and I have some short Jack patch leads which plug into the aux in sockets on the behringer unit. The plus side of this setup is that it's cheap (the behringer unit costs about £75) and works with headphones down to 8 Ohm but the downside is that you have to replug the headphones into each channel. Now I have 12 sets of stuff, I want to build a new 8 ch. rack and 4 ch. rack setup but I would like to have some sort of headphone amp system with a single amp to plug the headphones in and some means of selecting up to 8 receivers to listen in to, perhaps by rotary switch or push buttons. Does anyone have any ideas on how I might do this or if there is an off the shelf unit for this application? I've had a quick search around, but nothing jumps at me and I'm sure I can't be the only one who wishes to do this - mind you according to Sennheiser I am the only customer to have recurring failures of the up/down buttons on their bodypacks so maybe I'm unique! Michael Link to comment Share on other sites More sharing options...
Lamplighter Posted September 26, 2007 Share Posted September 26, 2007 MichaelI had a similar problem with 10 channels, solved by buiding a box with 10 buffer amplifiers and a bcd decoder controlling cmos switches. The channel inputs were taken from the mixer insert points, the selected output was fed to a single stage amplifier with an output transformer. This was fed via a 6 core screened cable to the earpiece of a telephone handset backstage. The microphone was replaced by a bcd switch. 1 cable pair carried the audio, 1 wire = bcd input 3 wires = bcd output, the last bcd output was added later as a phantom on the audio pair. A cat 5 cable would have been suilable but the 6 core was in situ. The cost was minimal, mainly time and a set of TRS jack plugs. It works well but is not so easily expandable as rotary bcd switches are normally only 10 position. I couldn't find a comercial unit to perform the same function.Brian Link to comment Share on other sites More sharing options...
PoppaDom Posted September 26, 2007 Share Posted September 26, 2007 Simplish solution could be to feed the jack outputs of the recievers to a simple rotary switch mechanism which is then connected to the a single headphone amplifier stage output to feed your headphones. Something like CPC Part code SW02747 connected to each output with all the screens commoned then feed the output into CPC Part code DP28376 all mounted into a 2U blank panel at the bottom of the rack with a power supply attached to the rear. Reasonably cost effective and easy to build. Yes there will probably be a small click when turning the rotary but it should be minimal, and in headphones not the end of the world! This solution has worked for me in the past and I have seen similar solutions attached to another hire companies stock. If you require more info just ask Poppadom Edit: Forgot to mention that the solution can be made more elegant with some other simple electronics, more info if required! Link to comment Share on other sites More sharing options...
MarkPAman Posted September 26, 2007 Share Posted September 26, 2007 How about something like Behringer's Eurorack Pro RX1602 which is about the same price as the headphone amp, but will take 8 stereo inputs & mix them to one headphone out (and main out & effect/mono out). You'll be able to use the mute button on each channel and just un-mute the one you want to listen to. Link to comment Share on other sites More sharing options...
peternewman Posted September 27, 2007 Share Posted September 27, 2007 A not particularly helpful answer here, but it should allow you to carry on searching. When Joseph toured into us sometime last year, they had what appeared to be a professional version of what you want, 1U rackmount, a light coloured front panel IIRC (beige possibly) an LCD to display the channel number selected, and a rotary knob of some description to select a channel. I'm pretty certain this is all correct, although it was a while ago, anyway if you can find out who hired sound for it, they can probably tell you what the box is and who sells it. Link to comment Share on other sites More sharing options...
david.elsbury Posted September 27, 2007 Share Posted September 27, 2007 I have seen them documented as custom builds from the major sound companies in the USA... Masque or someone like that but that's about all I remember, sorry. Maybe try asking at the Theatre-Sound list? David Link to comment Share on other sites More sharing options...
dbuckley Posted September 27, 2007 Share Posted September 27, 2007 ... and some means of selecting up to 8 receivers to listen in to, perhaps by rotary switch or push buttons. Our friends at Kramer do a Eight channel audio switcher and you could daisy-chain two of them; its all balanced so you can just passive split the signal using Y cables from the receiver to both this thing and a A2D. About 400 quid... http://www.kramerelectronics.com/images/machina/VS-2481.jpg Link to comment Share on other sites More sharing options...
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