chatterbox Posted October 27, 2012 Share Posted October 27, 2012 Did a gig last night at a high profile venue with in house system supplied ( well not in house- but they have a company they use - wont mention any names but Aussies will know)). Midas Venice desk (Urgh - not my favourite)and Klark graphics. Midas has ( god knows why) 2 x fx sends (post) + 2 x mon sends (pre) + 2 auxes (switchable). We were using all 6. The 2 mons sends were being used for 2 pairs of iem. When send straight from the desk with no graphics - all was fine - but as soon as any of the Klark graphics were put into the chain - both mon sends sent to both iems.... Techs and us couldn't work it out ( well not in the amount of time we had) - is there some sort of bridging/summing mode that might have been done in the graphics???...(all the same cabling was used when the graphics were out of circuit) or is there a fault?????(Being as the midas had been configured to be pre eq as well - the iem sound was dreadful - having no eq and no graphics....) Link to comment Share on other sites More sharing options...
david.elsbury Posted October 27, 2012 Share Posted October 27, 2012 Do you mean that the Klark EQ's (DN360s?) were ok when run in line, but no good when inserted? If so, were the inserts 1/4" TRS jack to twin XLR? If so, I would suggest that the insert cables are wired for pin 2 hot, pin 1+3 cold. However the Klark EQs are pin 3 hot. Of course, this might be way off base. But it sounds similar to a situation I run into from time to time at work. David PS, I think I know which company you refer to, if so I work for them in Auckland. Hence my suspicions above. But not sure why you are being cagey about the details? :) Link to comment Share on other sites More sharing options...
brainwave-generator Posted October 27, 2012 Share Posted October 27, 2012 No he is saying that when he didn't use the graphics, the auxes were separate; and when he did use the graphics, they were summed. Thus proving that the fault must have been in the graphics and not elsewhere in the system. Link to comment Share on other sites More sharing options...
Rob_Beech Posted October 27, 2012 Share Posted October 27, 2012 We could do with establishing if they are 360's, they do a range of course. It does seem rather odd. I'm not familiar (or fond) of the venice enough to know its options. I assume there is no switching on it to make those pair a stereo mix with a gain and pan control? Does sound odd and unless there some magical switching in the desk it does sound like a graphic thing. The 360's are unbalanced pin 3 hot by default as David says. Link to comment Share on other sites More sharing options...
mackerr Posted October 27, 2012 Share Posted October 27, 2012 (all the same cabling was used when the graphics were out of circuit) or is there a fault????? Does this mean the graphics were inline, and you took the cable from the input to the graphic and plugged it into the cable from the output to bypass the graphic? There is nothing intentional in a KT360 or any other graphic, KT or otherwise, that will combine the 2 channels of a dual channel eq. Mac Link to comment Share on other sites More sharing options...
chatterbox Posted October 28, 2012 Author Share Posted October 28, 2012 TO answer all the above questions. DAVID - No they were not inserted it was when they were put in the chain that we had the problem , and I wasn't being cagey - it was Staging Connections.ROB BEECH - Yes I believe they were 360's...there were no controls on the Venice to sum the mons or give a stereo feed etc....BRAINWAVE and MACKERR - yes you are correct SO far everyone as well as us is still baffled as to the cause of the fault....bummer..it def had us all scratching our heads, and time was running out, so we just went with no graphics..... Link to comment Share on other sites More sharing options...
vlfaudio Posted October 28, 2012 Share Posted October 28, 2012 If one or both of the send cables was phase reversed it might cause this, assuming the ground is commoned between the two channels inside the graphics. Add cables wired for unbalanced pin 2 hot with pin 3 linked to ground and bingo ! Just realised there doesn't need to be a phase reversal to achieve this, but using unbalanced jack to XLR cables wired as I previously mentioned for pin 2 hot would cause the problem described. I used to work on a rig with DN27 over FOH which had to have their own specially wired insert cables. Ended up opening them up and rewiring them pin 2 hot so inserts and patch cables were interchangeable for all the XLR gear in the rack. Link to comment Share on other sites More sharing options...
mackerr Posted October 28, 2012 Share Posted October 28, 2012 If one or both of the send cables was phase reversed it might cause this, assuming the ground is commoned between the two channels inside the graphics. How can an out of polarity cable cause this crosstalk? Common practice is to run balanced audio into the DN360 despite its unbalanced pin 3 hot input, and audio on pin 2 does not have any detrimental effect. If the audio pins are connected to ground inside the eq, that would qualify as being a broken eq in my book. Mac Link to comment Share on other sites More sharing options...
vlfaudio Posted October 29, 2012 Share Posted October 29, 2012 @mackerr, Obviously it was far too late for me to be doing logic puzzles in my head. The answer is in the wiring though, the signals from both channels are getting commoned somewhere, and the most obvious place for that to happen is either via chassis ground or signal ground. I'm assuming unbalanced jack to XLR's are involved; there shouldn't be any problem with proper balanced cables or unbalanced ones wired correctly for pin 3 hot use. I've learned the hard way that using unbalanced pin 2 hot cables with KT's causes unpredictable results. Link to comment Share on other sites More sharing options...
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