raymond.faccini Posted December 3, 2013 Share Posted December 3, 2013 We done a show on Sunday and had a hell of a job with our sound system ,It worked fine in the morning during rehearsal as the show started the whole system stopped working we managed to get it going again but only one speaker channel was working we managed struggle through the show on very poor sound. We were working with four condenser mics [therefore phantom power] and four radio mics connected to the amp and the mics by XLR cable, it has been suggested to us this could be the problem. Does anybody out there agree or should we be looking further. Any help would be very much appreciated. Link to comment Share on other sites More sharing options...
ddproduction Posted December 3, 2013 Share Posted December 3, 2013 Much more information needed here. Define "the whole system stopped"? Link to comment Share on other sites More sharing options...
Shez Posted December 3, 2013 Share Posted December 3, 2013 Phantom power doesn't generally cause problems with radio mics as long as their outputs are balanced. What mics are they? Link to comment Share on other sites More sharing options...
raymond.faccini Posted December 3, 2013 Author Share Posted December 3, 2013 Phantom power doesn't generally cause problems with radio mics as long as their outputs are balanced. What mics are they? these mics are KAM 1940 UHF wireless radio mic kits with two hand held transmitters receiver that takes two balanced X.L.R. audio outputs Much more information needed here. Define "the whole system stopped"? every thing went off but we still had power the lap top ,mics or anything attached would not work, we disconnected one speaker channel and it came back on but very poor sound, we reconnected the speaker channel and worked for a short time and the same thing happened, but by working on one channel we managed to finish the show, although it was suggested to us that it was the phantom power causing the problem, I am wondering if it is more likely to be problem within the mixer itself. Link to comment Share on other sites More sharing options...
ukdeveloper Posted December 3, 2013 Share Posted December 3, 2013 every thing went off but we still had power the lap top ,mics or anything attached would not work, we disconnected one speaker channel and it came back on but very poor sound, we reconnected the speaker channel and worked for a short time and the same thing happened, but by working on one channel we managed to finish the show, although it was suggested to us that it was the phantom power causing the problem, I am wondering if it is more likely to be problem within the mixer itself.My first thought would be your board is failing. Either that or (more unlikely) you have an electrical problem somewhere. Using phantom power on channels that don't require them is not usually an issue as long as you are using balanced connections. I would be tempted to use some downtime to run valuable tests on your desk. What desk is it by the way? As another poster has said you should provide as much info as possible, letting us know what's plugged in what, and where and EVERYTHING else. UKD. You mic specs state: "Individual balanced XLR audio outputsUnbalanced jack 'mix' audio output" Im assuming, you're running properly wired XLR cables rather than the jack out? UKD. Link to comment Share on other sites More sharing options...
Doug Siddons Posted December 3, 2013 Share Posted December 3, 2013 One side of the mixer stopped working after speaker was connected so this means the problem is with the output of the amplifier or the speaker. Try plugging the good speaker into the dodgy output and see what happens. Link to comment Share on other sites More sharing options...
p.k.roberts Posted December 3, 2013 Share Posted December 3, 2013 From what you've said, I'd hazard a guess that the radio mic/phantom power 'issue' is a red herring and nothing to do with the problems you had. Does the mixer have an amplifiers built in or are you using a separate amplifier? I think the fisrst thing to do is try and isolate which bit of kit (or even cable) is failing. Link to comment Share on other sites More sharing options...
Simon Lewis Posted December 3, 2013 Share Posted December 3, 2013 Actually, I have had some unpleasant things happen when putting phantom up the output of lower cost radio receivers. I tend to either use the jack output and line level input to the desk, or not use phantom... Link to comment Share on other sites More sharing options...
Stuart91 Posted December 3, 2013 Share Posted December 3, 2013 I've had a number of customers who have contacted me about problems with KAM radio mics, none related to phantom power, they just seem to be very poor units. It seems that whilst they are tolerable for use as single systems, once you start running multiple systems the problems start. They're fine for a Zumba instructor or Karaoke merchant, but the thought of running a panto with four of them makes me shudder. It would be worth checking that the laptop is going into your desk via jacks or phonos, and not through a minijack to XLR adaptor. Headphone outputs do not like phantom power up them. Link to comment Share on other sites More sharing options...
mkfs9 Posted December 3, 2013 Share Posted December 3, 2013 As above need more info on the whole setup. Is it powered speakers,and desk. Or passive speakers and mixr amp, or separate desk and amp.? Link to comment Share on other sites More sharing options...
sleah Posted December 3, 2013 Share Posted December 3, 2013 Not wishing to hyjack.... but presumably it would be straight forward to make a short 'phantom blocker' lead? I would guess a small capacitor inline with PIN 2 would do the job? They would be rather handy for use with desks where, to save 57pence worth of buttons, they 'feature' global 'all or nothing' phantom power. Link to comment Share on other sites More sharing options...
timsabre Posted December 3, 2013 Share Posted December 3, 2013 Not wishing to hyjack.... but presumably it would be straight forward to make a short 'phantom blocker' lead? I would guess a small capacitor inline with PIN 2 would do the job?They would be rather handy for use with desks where, to save 57pence worth of buttons, they 'feature' global 'all or nothing' phantom power. I think you would run into all sorts of impedance matching issues if you did this. Unless you use a big capacitor (100's of uF) I think you would find that the low frequencies would disappear from microphones. Link to comment Share on other sites More sharing options...
sam.spoons Posted December 3, 2013 Share Posted December 3, 2013 Wouldn't you need a blocking cap on pins two and three (not just pin 2)? Link to comment Share on other sites More sharing options...
dbuckley Posted December 3, 2013 Share Posted December 3, 2013 Not wishing to hyjack.... but presumably it would be straight forward to make a short 'phantom blocker' lead? I would guess a small capacitor inline with PIN 2 would do the job? You would need a pair of caps in series with pin 2 and pin 3. This is exactly what a desk without an input transformer does. The caps are quite large values though, as Tim as noted; something like 10uF is common. They would be rather handy for use with desks where, to save 57pence worth of buttons, they 'feature' global 'all or nothing' phantom power.Its more than a 57p switch, there's more PCB, more metalwork... Link to comment Share on other sites More sharing options...
sam.spoons Posted December 3, 2013 Share Posted December 3, 2013 As I thought, a single cap would only block 48VDC on one conductor.... death to any dynamic mic connected thus (and probably to the wireless mic receiver too) http://www.blue-room.org.uk/public/style_emoticons/default/unsure.gif Link to comment Share on other sites More sharing options...
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