Question about S\PDIF signal

  • Hello everyone,

    my comprehension is that we are (since a while) able to change the clock at which the digital port outputs its signal in order to fit digital projects created at different rates. It's not, however, possible to change the actual sampling rate of the digital output.
    IOW, such signal should still be at 44.1 kHz, but able to clock devices (i.e., DAW) at higher rates.

    Is this correct?


    I see a lot of debates on the matter on different forums, and it seems there's still much confusion.

    Still chasing a worthy one :/

  • Hello everyone,

    my comprehension is that we are (since a while) able to change the clock at which the digital port outputs its signal in order to fit digital projects created at different rates. It's not, however, possible to change the actual sampling rate of the digital output.
    IOW, such signal should still be at 44.1 kHz, but able to clock devices (i.e., DAW) at higher rates.

    Is this correct?


    That's not correct, since a while it is possible to change the sample rate on the KPA. It can be found in the settings, just select the right sample rate and if you have the new Floor KPA it can also be slave for SPDIF connection.

  • Ah thanks Navar, I did not load KAOS 7 yet.
    So it's now possible to set sampling rate and clock independently from each other?
    Would you be able to tell me since which version this is possible?

    Thanks again :)

    Still chasing a worthy one :/

  • Each specific sample rate requires a specific clock.

    In digital audio, it's not possible to run sample rate A while using clock B.

    Ah, thank you. So it has never been possible to change the clock alone while there was only one sample rate?

    From the Addendum document:


    [Ver 5.5] «The PROFILER can now generate a clock of 44.1, 48, 88.2, or 96 kHz. Your audio interface and DAW will be clocked at the selected rate and your DAW project should be set accordingly. Your audio interface must be set as a clock slave to S/PDIF, since the PROFILER itself cannot slave t an incoming S/PDIF clock»


    This quote seems to suggest that you changed the clock only, while keeping the digital signal from the KPA as it was.

    Am I missing something?

    Still chasing a worthy one :/

  • I'm not 100% percent sure, but sample rate and clock go hand in hand. So a sample rate of 48 kHz means a clock of 48 kHz. The Kemper can't be a slave, so it has to generate the clock itself.

  • I'm not 100% percent sure, but sample rate and clock go hand in hand. So a sample rate of 48 kHz means a clock of 48 kHz. The Kemper can't be a slave, so it has to generate the clock itself.

    I hear you. It seems quite strange tho that the manual only mentions the clock and disregards sampling frequency, which would seem much more relevant.

    Maybe someone from Kemper might shed a light on this? timo?

    Still chasing a worthy one :/

  • It is mentioned in the manual, in the second sentence of your prior quote actually. See the word RATE? ;)

    Not sure what you mean. The clock has got its own rate (frequency), so mentioning a rate in itself doesn't imply someone is talking about a signal's sampling rate.


    The DAW will be clocked at the same rate may just mean it will be driven by the set clock rate.


    This doesn't mean of course that the signal sampling rate is involved: I'd just not feel free to draw you same conclusions by just the paragraph you quoted.

    Still chasing a worthy one :/

  • Clock, as you put in parenthesis, is frequency. Sample Rate is frequency as well, e.g. 44.1kHz. Both have to match throughout the entire chain ... in other words, all participants have to speak the same language. The clock master decides the language to be spoken, all slaves have to follow.

    It's not that difficult to understand and Kemper hasn't invented the principles of digital audio. ;)