BNC or Coax?


Hi Everybody.

In connecting a USB converter (like a Trends 10.1 or CryoParts Pop Pulse) to a DAC, is BNC better than coax?
mmarvin19

Showing 4 responses by almarg

I suspect that you meant to ask whether a BNC connector or an RCA connector is preferred. The answer would be the BNC connector -- it is designed to handle high frequencies, and will provide a better impedance match to the cable (which is important for relatively high speed digital signals such as SPDIF, although unimportant for analog audio signals).

Regards,
-- Al
I have heard that BNC beats coax for video

Once again, BNC is a connector, and coax is a cable, so your question is unanswerable. Assuming you mean to ask whether a BNC connector is better to use for both video and digital audio than an RCA connector, the answer is yes (although either connector could very well be acceptable in both cases).

Regards,
-- Al
Here is more information on the SPDIF protocol, which as Ghostrider45 indicates can be transmitted over coaxial cable that can be terminated with either RCA or BNC connectors (and can also be transmitted over optical cable):

http://en.wikipedia.org/wiki/SPDIF

I wanted to add, in case it proves to be relevant, that RCA-to-BNC and BNC-to-RCA adapters are readily and cheaply available, although of course it is always good practice to avoid adapters where possible:

http://www.bhphotovideo.com/c/product/408187-REG/Hosa_Technology_NBR_253_NBR253_BNC_to_RCA.html#features

http://www.bhphotovideo.com/c/product/517840-REG/Mace_F_BNC_M_RCA_F_BNC_M_RCA_BNC_to_RCA.html

Regards,
-- Al
So, is the concensus that RCA termination or BNC termination is equally reliable for transmission of digital audio (say between transport and DAC)??? Or are there quantifiable differences between the two type of connectors?

I don't think it's readily quantifiable. The degree of sensitivity to impedance mismatch would be dependent, among other things, on the risetimes and falltimes of the digital pulses, which are not specified and probably differ among different components; the length of the cable; the amount of mismatch at both ends; and other factors. And the differences that the connectors make (such as the effects that impedance mismatch might have on jitter, resulting from its effects on waveform quality) might be overshadowed by other differences between the components being compared.

The best guide is probably just reading about other people's experiences with the particular components, and if possible auditioning them yourself.

Regards,
-- Al