Well, you concluded that I was a non-techie, so see what happens when you draw the wrong conclusion.
OK, I have more time now, so I will try to explain in terms that a non-native English speaker can understand. Look at how a BNC, TNC, Type-N, of even Type-F are made. -The physical dimensions- are roughly the same as the cable itself. This leads to very little discontinuities when you have to prepare the cable to go into the connector body. Now look at a XLR, and compare it to a twisted pair cable. See how much further apart the pins are? So, what happens when you have to break out the cable to go into the pins is that you have a *huge* discontinuity. And shows up on a TDR. As for the link you provided.............. We had engineers where I used to work that believed that anything under 200 MHz could use either 50R or 75R connectors. Well, maybe. Telecom............yeah, we did it all the time. SPDIF.........well, 99.x% use RCAs, and it works, so what? Here is the problem: Blame the guys who designed the SPDIF interface to begin with. (It was only designed as a test port.) They encoded the data in such a way that reflections muck up the clock recovery. How much reflections can you tolerate, or maybe one should ask how low it needs to be to be inaudible. Long story short, we concluded that you need to keep reflections to -30 dB (return loss) or less. So how does this relate to real world connectors? At that level, you can stick a 75R barrel in between 2 cables, and still make that level. I forget the actual number, but a 50R barrel is higher than that number. As for RCAs...............don't even ask. The link that you provided is kinda hard to read, and I did not readily see any scale information. It looks odd, as the impedance change from 50R to 75R is as big as the connector. Looks odd to me. 75 ohm RCAs.........yeah, I hear this nonsense all the time. I think Canare brags that they have one. (They can't!) Someone else claims that WBT makes one. But do they? Seems that they make some odd connector that has much of the outside metal removed, so that the inductance goes up, and therefore the impedance. Just one problem: This odd thing may indeed measure 75 ohms all by itself, but............. Once you stick it onto a conventional RCA jack, you now have all that metal that you went to great lengths to remove back in place. So, it really isn't 75 ohms once you mate it to a real-world connector. Did I address all of your issues? Pat -- ar-t http://www.analogresearch-technology.net ------------------------------------------------------------------------ ar-t's Profile: http://forums.slimdevices.com/member.php?userid=13619 View this thread: http://forums.slimdevices.com/showthread.php?t=52817 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
