OS7 Public Beta Discussion

  • This made my day! Thanks for experimenting and sharing!

  • the head/rack/stage all automatically lock to the supplied sample-frequency applied to it's IN. So if you only want to use S/PDIF in 1 direction only, the head/rack will 'slave' correctly, but this is not what is commonly known as slave mode.


    unfortunately the head/rack cannot slave it's OUT-clock to it's IN-clock due to a hardware issue in the used chip : so it's not possible to do a S/PDIF 'loop' : PC -> KPA -> PC (which would be needed for digital re-amping, and which is commonly called 'slave mode')


    there will always be digital signal on KPA's OUT, but the clock is not really locked to it's IN : so the audio-interface of the host can have problems locking to that signal : which is causing crackles in the audio / or no audio(sync) at all on the audio-interface.


    conclusions:

    - head/rack will automatically lock to any sample-frequency applied to IN

    - the sample-frequency selection in the UI determines the OUT sample-frequency

    - head/rack must be clock-master when using 2 S/PDIF cables

  • Yes, but this time was the first time I made a recording without any clicks and glitches without manually set my KPA to be the master clock.

    So I wonder if this new feature was pre-launched already in later versions of OS6?

  • I’m not sure how to interpret kpahuitsing ’s kind explanation when you just use 1 cable like this:


    KPA (slave) out > Soundcard (master) in


    So no reamping but just playing the KPA through the studio monitors which is how I use my toaster 99% of the time.


    We seem to have 3 users reporting that recordings made with the KPA rack/head with OUTPUT as slave actually work.

  • I think it's the other way around. It can sync to anything connected to the KPA S/PDIF INPUT.

    So that's regarding the signal coming from your audio interface going to the Kemper.

  • This is not slave mode. In slave mode spdif slave(kpa in this example) needs to recover clock from spdif in and change clocking of the spdif output with the same clock as recovered.

    In your example in may be a coincidence that it is working without clicks or your interace has some kind auto clock mode and switch itself to external spdif clock.

  • when using 1 cable only: KPA -> soundcard, then the soundcard has to be able to sync _and process_ from external clock, and most of the time has to be put to 'external sync' however there are some soundcards which do some form of auto-switching (so: DamianGreda, lightbox and DaanJM answers all are correct)


    MuktiG : I think there are 3 possibilities why it works for you:

    a) your audio interface somehow automatically adapts to the external clock coming from the KPA

    b) you've set your audio interface to 'external-sync'

    c) the samplingrates of the KPA and the audio interface are close enough not to hear any artefacts


    what kind of audiointerface do you use?


    Janne : yes this feature has been around for a while (it was implemented at the time the multiple frequency support came; I'm not sure exactly which release that was)

  • So on the Stage, what setting need to be made on the spdif page for it to sync to external clock from my Motu 1248 which is slaved to my Apogee Big Ben?

  • So on the Stage, what setting need to be made on the spdif page for it to sync to external clock from my Motu 1248 which is slaved to my Apogee Big Ben?

    in OS7.05 it's on the same page (spdif page)

    note: there is a software bug which prevents the slave mode from working correctly at the moment on the Stage.. we're working on the fix.

  • MuktiG : I think there are 3 possibilities why it works for you:

    a) your audio interface somehow automatically adapts to the external clock coming from the KPA

    b) you've set your audio interface to 'external-sync'

    c) the samplingrates of the KPA and the audio interface are close enough not to hear any artefacts


    what kind of audiointerface do you use?

    I haven't tried it yet. I'm wrestling a deadline to learn 20 songs and program them in the Stage. I really shouldn't be on the forum. ;)

    I was just referring to posts 315 and 316 where pictures are shown of working setups where the sound card is set to internal clock.


    It's has to be one of those 3 reasons then, so has something changed in the software to allow this behaviour?

  • Did that auto-sync-on-input arrive with os 6 already?


    It would explain why I managed to record a 4 track session without any glitches even when I forgot to put the KPA as master... 8|

    As kpahuitsing said, Janne, either your interface automatically synced to the incoming clock from the Kemper (from the KPA's S/PDIF output), you set the interface to do so or you just got lucky.

    In your example in may be a coincidence that it is working without clicks or your interace has some kind auto clock mode and switch itself to external spdif clock.

    Agreed, Damian.

    I was just referring to posts 315 and 316 where pictures are shown of working setups where the sound card is set to internal clock.


    It's has to be one of those 3 reasons then, so has something changed in the software to allow this behaviour?

    Ahh... but those pictures show the KPA displaying the clock rate when synced to the input. The input rate and input synchronisation are derived from the input's S/PDIF source in this case, but it's not carried through to the output, which remains "free-running". IOW, even 'though the output's rate matches that of the input, the synchronisation of the output, bit-for-bit, isn't "in-time" with the input.


    Another way of putting it:

    Marbles drop into a bucket at the rate of 1 a second. There's a hole in the bucket that allows a marble to drop out of it at the rate of 1 per second. That's where the similarity ends - the input and output rates are the same; there's very little chance that a marble will enter at the precise moment that another one leaves. The marbles are the digital soundstream's bits and the bucket is the Kemper.

  • As kpahuitsing said, Janne, either your interface automatically synced to the incoming clock from the Kemper (from the KPA's S/PDIF output), you set the interface to do so or you just got lucky.

    Ok, I read his explanation the other way around... :S

    So I must really have had a extremely lucky day then... I did 4 complete tracks of rhythm guitar one day and then the day after I realized that I had forgotten to sync the interface with the KPA. ||

    Fired up the project in Logic and went though all 4 track both visually and by ear and not a single click in any take! :saint:

    Never have had that happened before...

  • So I must really have had a extremely lucky day then... I did 4 complete tracks of rhythm guitar one day and then the day after I realized that I had forgotten to sync the interface with the KPA. ||

    Fired up the project in Logic and went though all 4 track both visually and by ear and not a single click in any take! :saint:

    Never have had that happened before...

    Are you sure your interface doesn't have some sort of auto sync, Janne?


    I know that MOTU, for example, doesn't offer it with most of its pro AVB line, but IIRC the 1248 in fact does have it - it adjusts to whatever's incoming and even performs on-the-fly sample-rate conversion, making the entire affair "transparent" to the user. IOW, if your interface does this, you wouldn't even know about it unless you were aware of the feature.

  • Well mine is an old Line 6 UX8 so there's no fancy anything on it and once I set the clock to internal, the KPA synced up at 48Khz but the display still said 44.1. Very strange.

    PS. I only have one spdif cable leaving the out of the KPA into the in on the UX8

  • Before 7.0.5, my Focusrite would never Sync, or make a sound, unless the clock was set to: S/PDIF (external clock), and the sample rates also had to match.


    With 7.0.5, at 96KHz, and the Focusrite set to Internal clock, it works well for me. I understand now that only the Stage model can re-amp in this way.

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