NPC SPDIF Output Impedance

When purchasing an RCA to RCA cable for connecting the NPC’s SPDIF output to the input of the DAC, what is the correct impedance cable to use? My run will be about 5 meters. Thank you!


75 ohm…

Thank you.

The problem is RCA jacks and plugs are 50 ohm. The best you can do short of replacing them with true 75 ohm BNC connectors and plugs is get 75 ohm cable and live with the end results. I use I2S between my DAC and the NPC and USB to the computer for archiving.

Thanks for the info sixpack1. I found a cable company who says that the company they use for raw materials, Canare, makes some true 75 ohm RCAs but who knows for sure. I will check into I2S and see if it is workable for me.

Thanks again!


I know some manufacturers claim true 75 ohm RCA’s but the physical size of the contacts and limited dielectric make that very questionable. There are some crimp on’s that may be closer to 75 ohms but not by much! You are very welcome for sure.

Yup the Canare crimp on connectors attempt to maintain the same conductor dimensions when transitioning from the coax to the connector. I did, however, get an audibly acceptable signal using a star quad microphone cable with a couple of cheap “Vampire” RCAs
soldered on. My run is only six feet so probably coat hanger might even work.

6 feet sounds like a good length. Lengths that are too short tend to have more issues with reflections. This is true mostly for Coax and AES EBU connections of course the impedance of the AES EBU is 110 ohm.

Of course, then there are the crème de la crème of digital cables starting at $9,000 for the first meter…