Digital output audio spike on startup

  • I'm using the Kemper digital out into an RME UFX and I'm getting a full volume audio output spike when the Kemper starts up.
    It's occurring when the startup progress bar is around the "P" in Kemper on the startup screen.


    Can anyone else confirm this is happening when using the digital outs on their rigs?


    I sent in a request that all the Kemper outs are muted until it's fully started up but I'm not sure if it's the Kemper or the UFX that is the problem.


    I can work around by muting the UFX dig input in it's mixer, but if I forget it scares the crap out of me.


    thx

    These profiles go to 11!

  • I've had the same thing on SPDIF since I first got my KPA (2012).
    Can't say for sure that it happens each startup because often I have to reset my interface to 44kHz after I've started up.
    Yup, it is quite scary when it happens if my amp is turned up loud.

  • I don't know, that's why I was asking. If those who have this issue wouldn't mind, please list your DAW interface and your startup procedure... Kemper and interface on at same time, or one after the other.


    RME UFX on first, set to internal sync
    When I turn on the Kemper, I get the audio spike AT FULL OUTPUT before the UFX switches to AES sync. I'm using 5.6.2 Spring Verb preview OS.

    These profiles go to 11!

  • Have you tried to set your interface to external sync before you switch on the Profiler?

    I have just tried that and it still pops. (RME interface connected via AES input)


    Having thought about that, there's a possibility that, where there is no AES input, the RME could revert to internal clock and not show this on the software.

  • I have just tried that and it still pops. (RME interface connected via AES input)
    Having thought about that, there's a possibility that, where there is no AES input, the RME could revert to internal clock and not show this on the software.

    AFAIK RME interfaces always use their internal crystal anyway and the external clock is just used as some sort of reference. I dont get any loud clicks or pops with my interface (Roland Quad capture). Or the issue is caused by the fact that you are using AES while the quad capture uses S/PDIF.

  • AFAIK RME interfaces always use their internal crystal anyway and the external clock is just used as some sort of reference. I dont get any loud clicks or pops with my interface (Roland Quad capture). Or the issue is caused by the fact that you are using AES while the quad capture uses S/PDIF.


    According to the manual the RME (Fireface 802) "switches from the internal quartz ... to a clock extracted from the input signal"
    The RME doesn't have an S/PDIF input but the 'official' solution is to create a phono to xlr cable.


    Not really an issue for me anyway as I drop my monitor levels before switch on ... sometimes!

  • Here's an old thread I started about a similar issue back in 2013.


    Mr. Kemper, can you please completely mute the KPA during startup in Tuner mode.


    I believe this particular issue went away, but I still get a brief audio spike sometimes.
    Strangely, I can't reproduce it at the moment. Last time it happened was last week.


    Setup is KPA to Presonus Firestudio via SPDIF
    KPA always set to master. 44kHz
    Quite often I don't have synch because Firestudio sometimes reverts to 48 and I have to re-set.

  • Have you tried to set your interface to external sync before you switch on the Profiler?

    Yes, the spike occurs whether the UFX is set to internal or AES. I just usually leave it to AES and it switches sync automatically when needed. It's very consistent, always happening when the startup is about 1/3 of the way through.

    These profiles go to 11!

  • Since i cannot recreate the problem with my audio interface using a straight coaxial S/PDIF connection i can only assume that it might be caused by the fact that you are using some sort of converter cable to go from S/PDIF to AES/EBU or that your RME interface produces a click as soon as it receives the external clock and switches to it. You could either turn on the devices in a specific order to avoid this or mute the channels in your DAW.

  • Since i cannot recreate the problem with my audio interface using a straight coaxial S/PDIF connection i can only assume that it might be caused by the fact that you are using some sort of converter cable to go from S/PDIF to AES/EBU or that your RME interface produces a click as soon as it receives the external clock and switches to it. You could either turn on the devices in a specific order to avoid this or mute the channels in your DAW.

    Just happened to me again.
    I go straight from my KPA to SPDIF on my Presonus interface.
    Large scary "spike" happened during startup when KPA switched from startup screen to tuner screen. Sounds like an initialized (empty) profile being played hard for about a second. I actually was watching the KPA screen as this happened.
    My speakers were turned up, and it scared the life out of my cat that was sitting on top of one.


    Latest release, no converters

    Edited once, last by Gizmo: Damn auto-correct ().

  • I contacted RME and asked if there's any output when changing sample rates or sync modes and they said no and it's the Kemper causing it. Since I've used a lot of gear and never had the issue except with the Kemper, I tend to agree.


    I also asked about using the converter cable from spdif to AES and they said if I'm not having any issues when recording or playing back, then it's not the cable causing it only during startup, which also makes sense.


    Muting the RME mixer channel on startup works, unless I miss it.

    These profiles go to 11!

  • I have the same issue with my Babyface. I don't know if it's due to the fact that I have to run converters or not. But I get a whole bunch of nasty noises.

    Disclaimer: When I post demo clips for profiles, there will be some minimal post-processing, unless stated otherwise. I normally double-track hard L/R, and add to the main buss a small amount of EQ and a limiter/comp set pretty light as well. Sometimes I get test profiles in advance of release, though 90% of my clips will be from packs I have purchased.