RCA SPDIF?

  • Looking into purchasing 2 SPDIF cables so I can connect my kemper to my Saffire Pro 24.


    I haven't used an optical cable since the Mini Disc days and many of them seem to look totally different.


    After looking up the manual for my Audio Interface it says that it's a RCA SPDIF.


    On the Kemper I believe it's just SPDIF. Am I correct?


    Does this mean I'll need some kind of converter?


    Also I'm assuming that because it's a digital signal the quality of the cable is not overly important?


    Any help or advise would be appreciated.

  • I bought a small RCA/Spdif to optical converter to use with my RME UFX.
    While it worked well, I've decided to just use the analog inputs of the RME.
    I have to be able to work at 48k and I don't imagine the Kemper will give the option any time soon if ever.


    I can't hear any difference in tone between digital outs and analog.

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  • Yes. These are what I use.


    I bought a small RCA/Spdif to optical converter to use with my RME UFX.
    While it worked well, I've decided to just use the analog inputs of the RME.
    I have to be able to work at 48k and I don't imagine the Kemper will give the option any time soon if ever.


    I can't hear any difference in tone between digital outs and analog.

    Just one conversion and you may not hear much or anything, but any time you convert digital to analog or analog to digital, or better yet digital to analog to digital, you get some degree of degradation. S/PDIF keeps things in the digital realm and preserves the integrity of each transfer.

  • Just on the S/PDIF from KPA to UFX caper - there is no need for the optical converters.


    The S/PDIF input and output of the Kemper can talk to the AES/EBU input and output ports on your UFX. You just need to source the right cables or to convert a mic cable into two of them by dividing it and fitting an RCA connector to the correct wires at each of the cut ends. Balanced lines have the signal on the two internal lines and no signal running on the shield. RCA plugs have two connections - one to the central pin and one to the outside clamp.


    RME OK's this by the way. Their head engineer (MC) suggests this himself on their forum. The AES/EBU spec involves compatible electrical signals to those used in S/PDIF - just set up for longer cable runs and using more robust connectors (XLR) for use in a professional environment.


    Either get your local tech guy to do it or, if you are handy with a soldering iron, just get a standard mic lead that is double the length you want for the cable run and cut it in half and fit the RCA plugs to the cut ends of each half. You should be able to source advice on what pin connects to what on the RCA plug online.


    If you get it wrong on the first try, do what they did on Lost in Space and reverse the polarity ;)


  • Wish I could find cables like this readymade, but they aren't available anywhere. I can't even find any pictures where anyone has done this.

  • Yes. These are what I use.

    Just one conversion and you may not hear much or anything, but any time you convert digital to analog or analog to digital, or better yet digital to analog to digital, you get some degree of degradation. S/PDIF keeps things in the digital realm and preserves the integrity of each transfer.


    I think while this holds true in theory, modern AD/DA converters are pretty damn good even with budget interfaces. Comparing SPDIF to analog outputs, you're likely to hear more difference due to the cables being used than due to the converters.


    If you're planning on running your interface at different rates, analog is the way to go. That said, there really is no reason to go above 44.1khz, according to most audiophiles. Plus, assuming your system is fast, you will experience less latency at higher sample rates.


    Also, if you are planning on running the Kemper through a preamp of some kind (I think this is the way to go with recordings that sit well in YOUR mix), SPDIF won't be able to help there.


    SPDIF is definitely the way to go when reamping. Just keep in mind that you have to connect both the ins and outs for reamping, can't have one without the other.

  • Good to know on the AES balanced to RCA cables. I actually have an old Tascam IF88-ie that is a format converter box with AES and RCA spdif jacks on it. I’ve been hanging on to it since back in the DA-88 days and will use it or make some cables up.


    48k is the standard for music being laid back to picture. I’m not a fan of converting audio from 44.1k to 48k and it’s a pain having to select a different sample rate for every track in a session I bounce out to be delivered. It’s easier to just record it all at 48k even if there isn’t a big audio difference between the rates. It also eliminates the possibility of me delivering files at two different sample rates by mistake.


    I’ll use audio in to record on sessions and will keep the AES wired up for sending back to the Kemper or if I’m working at 44.1k.

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  • The directions on wiring XLR pins to RCA I got from forum posts back in the day (quite some years - I was getting info on doing this stuff from studio dudes on the logicusers email list when god was a boy) - KVR audio forum has some discussion on stuff like this and you might turn something up with a search on the RME forum.


    https://mediarealm.com.au/arti…ing-standard-3-pin-5-pin/


    [Blocked Image: http://mediarealm.com.au/wp-content/uploads/2013/04/XLR-Wiring-Standard-3-pin.jpg]


    The above site supplies diagrams. Pin 2 and 3 carry the two sides of the signal in an XLR connector and those are the ones you connect to the two points in your RCA connector. I would guess Pin 2 (+ve) to the central pin in the RCA and pin3 (-ve) to the clamp on the RCA and test that it is connected correctly and not shorting out with a meter and then try that wiring first for a successful S/PDIF connection and if it doesn't work just reverse the connections on the RCA. When you've got it right put your heat shrink and strain relief in place and you should be able to use that until you retire ;)