henny Posted August 23, 2006 Share Posted August 23, 2006 hi im just planing the layout of the pach on a truck im rewireing , the current setup is as followes all the feed from everything in the van end up in a bank of krones there is then links from this to a bantam patch pannel, the current setup on both the krones and the bantams has the grouned commoned, what my question is if I was to conect coms (2 wire tecpro) down this system to allow sending of coms out down threw some of the muiltys that leave the truck would the common ground cause any problems ????? I guess not but thought I would check Link to comment Share on other sites More sharing options...
Bobbsy Posted August 23, 2006 Share Posted August 23, 2006 I also tend to use the common earth system when wiring patch panels and, in the past, have had problems with crosstalk when I've mixed balanced and unbalanced signals on the same system. Bob Link to comment Share on other sites More sharing options...
paulears Posted August 23, 2006 Share Posted August 23, 2006 in a studio situation I've found using the patch as the common earth point to solve more issues than it causes. one thing about comms. you need to devise some system to reduce the chance of mispatching comms into bits of kit that hate dc up the spout. bantams are better at not shorting when pulling a "live' plug out. 1/4" types often let the +v point touch the contacts on the way out. Link to comment Share on other sites More sharing options...
dbuckley Posted August 23, 2006 Share Posted August 23, 2006 I wherever possible send tecpro down the multi without ill effect to either the comms (which stay clean and silent) or to the audio. You will, of course, have your comms PSU in the truck on the audio power, not lurking backstage plugged into the lampies phone charger socket :D Link to comment Share on other sites More sharing options...
Bobbsy Posted August 23, 2006 Share Posted August 23, 2006 Agreed that I've sent comms down a multicore alongside programme audio many a time without any problems. However, where I HAVE had problems with crosstalk (as noted) is at the jackfield/krone frame end using a common earth. This applies to any unbalanced signal in my experience. Bob Link to comment Share on other sites More sharing options...
dbuckley Posted August 24, 2006 Share Posted August 24, 2006 Bobbsy, which way are you getting crosstalk...? Link to comment Share on other sites More sharing options...
Brian Posted August 24, 2006 Share Posted August 24, 2006 IIRC Techpro recommend that the earth is not connected to any other earths in the system. I had problems in a studio install where the comms was being earthed out at the studio wall boxes and was causing horrible noise in the camerman's comms. Lifting the earth made it go away. Link to comment Share on other sites More sharing options...
Bobbsy Posted August 24, 2006 Share Posted August 24, 2006 Bobbsy, which way are you getting crosstalk...? Well, this is a "was" from quite a few years ago but it was the unbalanced signals present at very low level on some of the balanced ones. A prime example of this was when we routed timecode (an unbalanced connector on Sony Betacam VTRs alas) via the main audio patchfields. You know how nasty timecode is, and it was quickly obvious that this was a problem. This led to an investigation and there was also crosstalk from comms circuits, albeit much harder to detect because it was a lower, less constant level. Separating the unbalanced stuff from the main Krone frame and treating it separately seemed to fix the problem. Bob Link to comment Share on other sites More sharing options...
dbuckley Posted August 24, 2006 Share Posted August 24, 2006 You know how nasty timecode isOuch! Separating the unbalanced stuff from the main Krone frame and treating it separately seemed to fix the problem.We're into idle musing territory here, but I'm wondering if this is down to grounding, or that the last lttle bit of the balanced pairs get seperated just before the punchdown. This is a known problem with Cat5, in that there are several terminations in a Cat5 run, during which places the susceptability to crosstalk is a known and designed-around issue. Link to comment Share on other sites More sharing options...
Bobbsy Posted August 24, 2006 Share Posted August 24, 2006 This wasn't a CAT 5 installation...it was a project I managed back in '99 and audio cabling was with various BBC PSN/PSF designation cable types, depending on the requirement. I don't doubt it was a grounding issue of some sort, but it was a design that SHOULD have worked. However, I always get nervous with a mixture of balanced and unbalanced signals floating around (note my bad tech pun?) because it often seems to result in unpredicted funnies. This idle musing had me curious...I MAY still have a CD with the spec and cabling plans on it. If so I might dig it out and see if it might shed light on anything. Bob Link to comment Share on other sites More sharing options...
peternewman Posted August 25, 2006 Share Posted August 25, 2006 I wonder if Time Team are having a similar issue, given their directors cueing has been quite audible a few times in the show. A few noticeable "run VT's" among other things. Presumably their comms won't be running through any shared sound desks, so it must be due to patch bays somewhere. PN Link to comment Share on other sites More sharing options...
Andrew C Posted August 25, 2006 Share Posted August 25, 2006 Having seen TT being filmed, I doubt it. The director is standing in the mud behind the camera. It's probably just the mic picking him up. Link to comment Share on other sites More sharing options...
Bobbsy Posted August 25, 2006 Share Posted August 25, 2006 Difference is...this weekend's royal effort is live (albeit with lots of tape inserts), not pre-recorded. I've notieced the gallery chatter as well...and suspect this is a perfect illustration of the problem! Bob Link to comment Share on other sites More sharing options...
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