How long can a Kemper last without power?

  • I've encountered a couple of occasions where the mains power has been cut to the Kemper for around one-second and it has not affected the unit.
    I'd assume that others out there have experience a similar situation.
    Obviously part of the power supply depends on holding a charge as part of the circuit which accounts for this.

    Now, i'm not suggesting that anyone experiments at the risk of damaging their unit but i'd be interested to know the longest power-cut that doesn't affect the Kemper.

    My guess is that a powered-head will be shorter than an un-powered one, owing to the extra load, and maybe the rack unit will last longer than a toaster as there less LEDs to power.
    There's probably other factors involved that i've not thought of too. I'm sure the tec-team have an accurate answer, knowing the component values of the power-supply circuit.
    I'm led to believe that the Kemper can recover normally from a power loss (ie without the proper shutdown procedure)

    disclaimer: Do not experiment at the risk of damaging your unit!

  • Any electrical device stresses a bit when it is 1st powered on, but safeguards are engineered in most things to handle the startup current these days. The KPA isn't a refrigerator so it won't pull that much anyway. Brownouts OTOH are not good for any device and I would not want my KPA plugged in and on when one happens.

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

    For my edification only... :D Kemper/Helix user

  • The gain settings could conceivably only affect a tube or transistor amp, IMHO, Gianfranco.

    Because it all takes place in the digital domain, gain alterations only produce different sets of 1s and 0s, and therefore use no more or less power when tweaked.

    I saw the smiley face, so I realise you may have been joking. ;)

  • Well, I was thinking that any (digital) gain would eventually be turned into a tension after the D/A converter, so Master volume being the same the Profiler would output the more current the more gain was set in the 01 domain... :/


  • I dunno why so many people think a power cut is necessarily damaging or harmful to digital devices. We're told over and over again it is damaging to a computer, but a computer works in a very, very different way. Behind the scenes, your computer's OS is caching data and memory, cleaning up old data, memory, and cache, backing up (if your computer does that automatically), reaching out to the internet and getting response data for services you're running in the background (or foreground), writing and reading to RAM and your hard drives, reading hardware analytics, and presenting a picture to your monitor tens of times a second. And that's a short list of the things I can think of off the top of my head.

    On a device like the Kemper, a power cut will not damage the unit, much like unplugging a digital pedal won't damage it. The only times a power outage would possibly result in a problem is if you're trying to write or restore a backup or you're trying to save something, and the power outage happens at that exact moment in time.

    If you use a power conditioner, every time you turn off the main power source, you're effectively cutting the power anyway.

    What we need to worry about, in the digital audio world, is power spikes. A power spike will fry your unit - sometimes to the point of no return, sometimes it might just be damaging a resistor or cap and you have a noisy or weird sound. This is why I don't understand why so many people don't use power conditioners.

    The shutdown process of the Kemper is not unlike the shutdown process of a computer - it closes down any processes the device has running, and once everything is complete, it powers off completely. On a computer, you might have 100 individual processes (each tab in Google Chrome is its own unique process, and there are tens of services that run in the background to keep everything up to date and running efficiently - everything from pinging a server to get the current time, to ones that are stagnant but help speed up application launches, every menu bar/task bar icon,etc.). On the Kemper, sure, there are processes that are running in tandem with the main OS, but, for the most part, there's not a lot of cleanup to be done. It might prevent some rig corruption from time to time, but I've been using my power conditioner to turn on and off my entire rack at once for about 4 or 5 months now, and I only had 1 issue with rig corruption, and that was when I loaded on a ton of stuff at once.

    Long story short (too late): I wouldn't worry about it.

    Guitars: Parker Fly Mojo Flame, Ibanez RG7620 7-string, Legator Ninja 8-string, Fender Strat & Tele, Breedlove Pro C25
    Pedalboard: Templeboards Trio 43, Mission VM-1, Morley Bad Horsie, RJM Mini Effect Gizmo, 6 Degrees FX Sally Drive, Foxpedals The City, Addrock Ol' Yeller, RJM MMGT/22, Mission RJM EP-1, Strymon Timeline + BigSky
    Stack: Furman PL-Plus C, Kemper Rack

  • Beautifully stated, great points, Doug. Bravo, mate!

    Well, I was thinking that any (digital) gain would eventually be turned into a tension after the D/A converter, so Master volume being the same the Profiler would output the more current the more gain was set in the 01 domain... :/


    You know what, Gianfranco? The outputs would indeed use a little more juice when cranked up. A teensy, tiny bit more, but more nevertheless, so I believe you're right. I was of course speaking of the digital gain / attenuation within the unit's not being able to use more or less power, and hadn't thought of the analog outs' possible contribution to power drain, so well done mate. An astute observation, IMHO.

    More gain = more Leds = more used power when tweaked... :saint: (just kidding)

    You might have been kidding, but IMHO this is also a valid observation, aehaem.

  • From the wiKPA:


    [[timo]] Turning the unit off with the chickenhead is better, since there are indeed some procedures during shutdown. It won't break your unit when you pull the power, but to keep performance up (boot time etc.), you should, at least once a while, shut it down properly with the chickenhead to give the system a chance to shutdown properly. The general recommendation is: use the chickenhead to turn the KPA off

  • I had been looking at getting a Kemper amp. I had already thought of getting an Uninterrupted Power Supply unit for other things. But figured I could plug the Kemper in to that so if I was in the middle of recording and the power went out. I'd be able to save and shut everything down.

  • Oh yeah, that goes without saying, Damian. Not! LOL

    You might be onto something nere, my friend, but I really couldn't say :)

    I think I could be, Gianfranco.

    Obviously, gaps could be created by the saving and deleting of rigs, FX presets, IRs and so on. The consolidation of memory usage into seamless "blocks", one would think, would ensure optimal performance, and can only be achieved through some sort of defragging process.

  • Yes, Gianfranco, other than for the fact that other OS processes we're unaware of might be in progress at this time that require a few seconds to be completed.

    The recommendation that the Kemper be allowed to shut down the "normal" way once in a while would obviously serve as an opportunititty for the OS to simply catch up on defragging, if I've guessed correctly, and therefore ensure optimal performance in terms of response time where rig or preset selection / browsing is concerned. Said recommendation, being for an "occasional" clean-up (if I'm correct), would therefore help even those who do very little saving and deleting, but would restore optimal performance nevertheless... again, if I'm right.

  • If a device has a power supply that will automatically switch between input voltages, like a laptop computer and most other electronic devices these days, it will have what is known as a switching power supply. These supplies also have the benefit of being lighter, smaller and more efficient than linear power supplies (that are used in most tube guitar amps).

    One parameter taken into consideration with a switching power supply is called hold up time, which is basically how long a supply can output its rated voltage when the input power is removed. I'd suspect that the designers of the Kemper paid close attention to the supply design so that it would continue to operate for a short period if the input power is removed, as this would help tremendously with reliable operation with the flaky power you often see on stages (especially outdoors powered by generators). These power cutouts can be under a second, but some products will lock up and stop working with such issues.

    Many digital products will freak out when they are powered by generators, as they may not be able to handle the unstable voltages and intermittent cutouts. Analog amps and effects often work much better in such situations as their supplies by design hold a reservoir of power that will smooth out the variations. It is very gratifying to hear that the Kemper has a supply that will work under intermittent power cutoffs and brownouts.