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Thread: Why aren't 75 ohm BNC connectors used for SPIDF or even L or R outputs?

  1. #1
    Join Date: May 2008

    Location: U.S.A. Neo-Socialist Kalifornski

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    Default Why aren't 75 ohm BNC connectors used for SPIDF or even L or R outputs?

    Seems to me a well made BNC 75 ohm connector would be far better than an RCA connection.
    Was there a good reason to use RCA jacks, cost? politics ?
    I had a DAC that used one before and it worked well, why dose hi end audio still use RCA?
    Jeff :UBERTHREADKILLER

  2. #2
    Join Date: Jan 2019

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    I'm Andrew.

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    I would suggest that the main reason for this was the original joint mfg companies Philips and Sony . They wanted to ensure that the medium was universal and that it was something main stream users were used to . BNC has always been a niche socket .

    On the other hand there is lots of things that point to the non adoption of this connector as a chance for quality and consistency missed . BNC are the only connector which has a plug and socket specified as 75 ohm (be careful when buying there is also a 210 ohm BNC ) so if you have a fully specified 75 ohm cable with BNC 75 Ohm plugs at each end and the equipment at both ends fitted with 75 Ohm sockets then you would be able to at least be sure that you have a fully Red Book specified signal between equipment .

    I would also expect that when CD became mainstream and player prices were tumbling that all the OEM and mass producing companies who also made amplifiers etc would not have wanted the additional cost of adding another type of connector which would have meant additional cost and seperate storage ranther than jus use the already well accepted RCA standard .

  3. #3
    Join Date: Feb 2013

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    I'm Grant.

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    50 ohm and 75ohm connectors are the norm.
    Regards,
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  4. #4
    Join Date: Sep 2013

    Location: North Island New Zealand

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    I'm Chris.

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    Quote Originally Posted by goraman View Post
    Seems to me a well made BNC 75 ohm connector would be far better than an RCA connection.
    Was there a good reason to use RCA jacks, cost? politics ?
    I had a DAC that used one before and it worked well, why dose hi end audio still use RCA?
    Well done ! You are quite correct, it is high time manufacturers of CD players and DAC's provided a BNC and are advised by the buying public a RCA is
    not a valid connector for SPDIF
    What an opportunity to corner the market in not only CD players but also digital interconnects.
    Can't wait for it, to begin happening

  5. #5
    Join Date: Feb 2013

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    I'm Grant.

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    not sure i agree tbh. the differences for general use is minimal imo
    Regards,
    Grant .... ؠ ......Don't be such a big girl's blouse

    I've said it before and I'll say it again: democracy simply-doesn't-work
    .... ..... ...... ...... ................... ..... ..... ..... ..... .....
    FIIO K7 BT, M11 PLUS, BTR7, KA5 - OPPO BDP-103D - PANASONIC UB450 - PANASONIC 4K ULTRA HD TV - PIXEL 6 - AVANTREE LR BLUETOOTH - 2* X600 SOUNDCORE - HEADPHONES INCLUDE, FIIO, NURAPHONES', FOCAL, OPPO, BOSE, CAMBRIDGE, BOWER & WILKINS, DEVIALET, MARSHALL, SONY, MITCHELL & JOHNSTON - 2*ZBOOK'S- MERCURY BD ROM, ROON, QOBUZ, TIDAL, PLEX, CYBERLINK, JRIVER - MULTI HDD'S -

    Oh my god! There's nothing wrong with the bidet is there?

    “Nothing discloses real character like the use of power. It is easy for the weak to be gentle. Most people can bear adversity. But if you wish to know what a man really is, give him power. This is the supreme test. It is the glory of Lincoln that, having almost absolute power, he never abused it, except on the side of mercy".

    “You see these dictators on their pedestals, surrounded by the bayonets of their soldiers and the truncheons of their police ... yet in their hearts there is unspoken fear. They are afraid of words and thoughts: words spoken abroad, thoughts stirring at home -- all the more powerful because forbidden -- terrify them. A little mouse of thought appears in the room, and even the mightiest potentates are thrown into panic.”

    "You don't have free will. You have the appearance of free will.”

    “There's a war out there, old friend. A world war. And it's not about who's got the most bullets. It's about who controls the information. What we see and hear, how we work, what we think... it's all about the information!”


    ***SMILE, BE HAPPY***

  6. #6
    Join Date: May 2016

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    I'm Geoff.

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    My Allo Digione board has both RCA and BNC connectors. To my ears the BNC output is superior.

  7. #7
    Join Date: Feb 2008

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    I'm Neal.

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    AES3 the professional version of SPDIF uses 110ohm STP and XLR connectors. I read somewhere but for the life of me can’t find it now that the use of RCA connectors came about as a quick n dirty way to test SPDIF in the lab and somehow was deemed good enough and the use of RCA ‘stuck’....
    Listening in a Foo free Zone...

    Only a Sith deals in absolutes.

  8. #8
    Join Date: Jan 2009

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    I'm openingabottleofwine.

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    Quote Originally Posted by struth View Post
    50 ohm and 75ohm connectors are the norm.
    Agreed. I have never heard of a "210 Ohm" connector (if one does exist then it would have a very small centre pin, or have a very large OD.

    I suspect one reason why the superior BNC connector was not adopted was because, as you correctly point out, they come in two versions: 75 Ohm and 50 Ohm. If one tries to connects a 50 Ohm plug to a 75 Ohm socket, the socket will be damaged as the centre pin of the 50 Ohm version is larger.
    Barry

  9. #9
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    I have also seen 90 ohm used by NASA.
    Jeff :UBERTHREADKILLER

  10. #10
    Join Date: Jan 2009

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    Quote Originally Posted by goraman View Post
    I have also seen 90 ohm used by NASA.
    There is a BNC variant having a characteristic impedance of 95 Ohm, and used for video connections in the aerospace industry.

    https://en.wikipedia.org/wiki/BNC_connector
    Barry

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