PTA Posted March 15, 2012 Report Share Posted March 15, 2012 I've never got an answer to this, but when using a BNC cable to transmit timecode, what is the better resistance to use, 50 ohm or 75 ohm? Quote Link to comment Share on other sites More sharing options...
MatthewFreedAudio Posted March 15, 2012 Report Share Posted March 15, 2012 I use 50 ohm for all of mine and it works quite well. www.matthewfreed.com Production Sound Mixing for TV, Films, and Commercials Quote Link to comment Share on other sites More sharing options...
Jay Rose Posted March 16, 2012 Report Share Posted March 16, 2012 You're talking about standard LTC? I can't imagine any situation where the cable impedance would matter. That stuff - and all modern equipment using it - is designed to be incredibly robust. It can survive the address track on a 3/4" tape or even a phone call! Standing-wave jitter, rolloff, and other impedance gremlins can affect high speed data like s/pdif coax or Ethernet (or does anybody remember SCSI?), and cable impedance is important in some analog audio and most RF situations... but AFAIK, not timecode over the kind of cable lengths you'll find in a shoot or a studio. Quote Link to comment Share on other sites More sharing options...
PTA Posted March 16, 2012 Author Report Share Posted March 16, 2012 Awesome. Thanks guys! Quote Link to comment Share on other sites More sharing options...
Zack Posted March 16, 2012 Report Share Posted March 16, 2012 75 ohm, no issues Quote Link to comment Share on other sites More sharing options...
mikewest Posted March 28, 2012 Report Share Posted March 28, 2012 For short runs not critical. To manage power down and battery changes best use a t/code box mounted on the camera (for most cameras) mike Quote Link to comment Share on other sites More sharing options...
Michael Addlesee Posted February 19, 2021 Report Share Posted February 19, 2021 No one has mentioned the two common varieties of BNC connector. They are controlled impedance connectors and come in 50 Ohm and 75 Ohm. The 75 Ohm one has a smaller diameter centre pin. The consequence of this is that if you use a 75 Ohm plug with a 50 Ohm socket the centre pin may not make contact and your connection might be intermittent. More damaging is using a 50 Ohm plug with a 75 Ohm socket as the centre pin contacts on the socket can end up being permanently splayed out, so a subsequent 75 Ohm plug to damaged 75 Ohm socket may also become intermittent. I'm currently trying to get definitive information from Zoom about which they use on the back of the F4. Quote Link to comment Share on other sites More sharing options...
syncsound Posted February 20, 2021 Report Share Posted February 20, 2021 I've used 75 ohm short BNCs for timecode for years with no issues. Quote Link to comment Share on other sites More sharing options...
r.paterson Posted February 20, 2021 Report Share Posted February 20, 2021 All bnc tc os 75 ohm 50ohm connectors will eventusly trash the tc socket..its to do with pin diam..if yiu look at a socket you can tell right away what is 50 ohm.and 75 ohm https://labrigger.com/blog/2012/10/05/use-50-ohm-bncs-not-75-ohm/ Quote Link to comment Share on other sites More sharing options...
Derek H Posted February 20, 2021 Report Share Posted February 20, 2021 The cable impedance doesn’t matter at all. There is this issue with connector mismatch that may eventually cause an intermittent connection but I have yet to encounter that myself. you could use two coat hangers and still get timecode to jam Quote Link to comment Share on other sites More sharing options...
r.paterson Posted February 20, 2021 Report Share Posted February 20, 2021 Intermittent with TC isnt as big issue as if a bad genlock connector due to 50ohm plug .intermitent genlock on camera will ruin the entire video recording for that take..so best to stick to 75 ohm bnc for tc and genlock.. Quote Link to comment Share on other sites More sharing options...
Patrick Farrell Posted February 21, 2021 Report Share Posted February 21, 2021 On 2/19/2021 at 11:44 AM, Michael Addlesee said: No one has mentioned the two common varieties of BNC connector. They are controlled impedance connectors and come in 50 Ohm and 75 Ohm. The 75 Ohm one has a smaller diameter centre pin. The consequence of this is that if you use a 75 Ohm plug with a 50 Ohm socket the centre pin may not make contact and your connection might be intermittent. More damaging is using a 50 Ohm plug with a 75 Ohm socket as the centre pin contacts on the socket can end up being permanently splayed out, so a subsequent 75 Ohm plug to damaged 75 Ohm socket may also become intermittent. I'm currently trying to get definitive information from Zoom about which they use on the back of the F4. All BNC connectors manufactured to current specs will mate non-destructively. Sound Devices and all cameras I’ve bothered to check use 75 ohms for TC. But to reiterate what everyone else said, at the lengths we typically use it doesn’t matter. Quote Link to comment Share on other sites More sharing options...
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