Mixing Connectors on SPDIF Coax Cable

I have a new DAC coming. It has more connector options than my Oppo 205, including BNC. I’ve ruled out an adapter on one end of a BNC/BNC cable. Would a cable with mixed connectors be the way to go? In other words which would be better - RCA to BNC or RCA/RCA? Or not enough difference to bother?

Why have you ruled that option out?
Probably be the cheapest and most practical option to keep your current lead in use.

Adapters seem to be pretty much frowned upon around here. Plus I’d have to buy an adapter…

Just get the cable you need with the right connectors on it for the devices you’ll be using. If there’s a BNC option on the device, use it in preference to RCA.

What dac is it if I may ask?

Denafrips Venus II - it has BNC & RCA Coax SPDIF inputs. My Oppo 205 that will feed it only has RCA.

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I had the same concern about using adapters and mixed connection types. I contacted Nordost as all the 75 Ohm digital cables they make have BNC connectors and come with RCA adapters. Their take is that the 75 Ohm impedance is determined by the cable and BNC termination, and that this combination sounds better than RCA terminated cable.

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It doesn’t matter if connectors aren’t the same, though both should be 75 ohm. Some RCA connectors claim to be 75 ohm, though I am not sure if it is technically possible - but if connecting to a DAC with RCA then you have no option. My guess would be that a 75 ohm RCA plug is probably better than a BNC plug and BNC-RCA adaptor - but that is a guess, and might be worse (especially if the RCA connector is not actually 75 ohm).

Mixed connectors are fine… (though best ensure BNC connectors are 75 ohm as opposed to 50 ohm if you can)… also in practice converters are fine should you need to use them.
The loss and any SWR through any impedance mismatch of the connector is going to minimal and in practice have negligible if any affect. More important to ensure the coax used is 75 ohm characteristic impedance.

When we use the term 75 ohm, we are referring to the characteristic impedance of the connection between source and sink as well as the source and sink itself. This goes between the device interfaces, sockets, plugs and cable. This is called a transmission line.
If everything has the same characteristic impedance including the device interfaces, then there will be no reactive losses… but in practice a few percentage points of reactive loss is going to be irrelevant in connection between quality devices.

The point that some get excited about it, is that a phono plug and socket when connected can’t be 75 ohm CI due to its physical geometry… where as BNC plug and sockets can be. However as I say in practice this will be mostly if not completely irrelevant.

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Thanks Simon. Good information (as usual)!

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