Fix the issue that causes the KPA to lock up frequently while connected via USB to Mac

  • It's gotten to be a nearly daily issue where out of nowhere, sometimes while not even performing any kind of operation, the whole KPA including the Remote will just lock up, requiring a restart. Happens whether RM is running or not. Running the latest firmware and RM releases (not beta). I've seen enough others posting here about it that it's clearly a somewhat widespread issue.

  • For me it rarely requires a restart. Just pulling the USB is usually enough to get the KPA and remote working normally. That said, I agree it should be fixed. I submitted a ticket a couple years ago that either was lost/forgotten or nothing happened with, and recently filed another that now is in progress. To me the problem seems related to how USB works on the Mac when the screensaver and/or hibernation kicks in. The KPA can not protect against hostile attached devices maliciously exploiting some protocol, but a non-responsive attached device should never be allowed to block the KPAs operation. Any communications with external devices must be implemented with strict timers and interrupts to prevent lockups, or the communication has to be handled in a dedicated thread or process that may block periodically yet not be allowed to affect the operation of the rest of the system.

  • I have this issue as well, sort of. When connected to my Mac desktop I never, ever get a freeze. Even when my Mac sleeps, everything stays stable.


    But, connecting to either of my Mac laptops (older MacBook, newer MacBook) I'll get this problem all day long.


    Typically, I'll connect my Kemper to my laptop, using RM, in our band rehearsals, browsing between rigs in somewhat real time to find the tones I want. So very much easier to scroll through various profiles using RM than using the near impossible to read screen on the unit itself. The downside is I'll get about one freeze per session. At least.


    In part, the "solutions" I've found included never, never, never use battery power alone. Always have the external power supply connected. In 'settings' I select never sleep, never go to screensaver, never let the disc stop, keep the laptop in full function, fully on, never pause mode. I'll still get random freezes, but less often. In a rehearsal setting this is semi-acceptable, if annoying.


    But, once we go live, I'll disconnect the computer/USB. Freezing in the middle of a set is not okay. Too bad as well. It can be slightly easier (for me) to use RM to jump between performances. Not a deal breaker, but not ideal.


    We can only hope when the new Editor comes out that it won't exhibit the same problem.

  • I'm on a late 2015 iMac, 24gb RAM, SSD drive, 4.0GHz i7 processor - it's a fairly beefy machine and not a laptop, so battery isn't an issue. I'm currently running MacOS 10.14.5 but about to update to 10.14.6, don't think that'll make a difference but.....

  • Not trying to be nit-picky here, but you are running a 7.01 "beta" OS on the KPA, and wondering why it may have issues?

    If you use FRFR the benefit of a merged profile is that the cabinet is totally separated in the profile.


    For my edification only... ;) Kemper/Axe-FX III/ Quad Cortex user

  • Not trying to be nit-picky here, but you are running a 7.01 "beta" OS on the KPA, and wondering why it may have issues?

    That wouldn't be nit picky as Beta software is always buggy. I'm running the latest release version of both Rig Manager and KAOS, no betas.

  • Sorry, didn't read far enough where you said "no beta". :)

    If you use FRFR the benefit of a merged profile is that the cabinet is totally separated in the profile.


    For my edification only... ;) Kemper/Axe-FX III/ Quad Cortex user

  • I thought this issue was with non-responsive USB-hosts in general. Apple use generic USB-controllers AFIK so PC's with the same USB-controller/circuits should be affected too. Are there really no PC-users who have the same problem? Unfortunately I don't have a windows PC to test with (only MacOS and linux here).

  • I’ve seen this reported by PC users too. Mainly laptop users.

    I’m on Mac and have had my KPA connected for years without any problems. But I’m using a desktop so my guess is that it have something with the shutdown of the USB buss when the computer goes to sleep that the KPA can’t handle.


    This might be different depending on both the computer model and operating systems. And I’ve seen some user reporting similar problems that been solved by changing usb cables or usb hubs.

  • I’ve seen this reported by PC users too. Mainly laptop users.

    I’m on Mac and have had my KPA connected for years without any problems. But I’m using a desktop so my guess is that it have something with the shutdown of the USB buss when the computer goes to sleep that the KPA can’t handle.


    This might be different depending on both the computer model and operating systems. And I’ve seen some user reporting similar problems that been solved by changing usb cables or usb hubs.

    I'm on a Desktop Mac as well, no laptop. I do have an issue with my USB hub (oddly enough it was using the Kemper with it that alerted me to the issue LOL) so I now connect it directly to my Mac, not the hub. But the issue happens, of course, when the Mac goes to sleep but I've also had it happen without the computer sleeping. Until there's a fix the only workaround I can find is to disconnect the USB cable when not using Rig Manager. Not sure why they won't just fix this, it couldn't be that huge a fix could it?

    That said, though, that's small potatoes when compared with the plethora of amazing tones the KPA allows so not that much of a biggie...