QU16 – New firmware – Phantom power pop?

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This topic contains 9 replies, has 7 voices, and was last updated by Profile photo of fxk fxk 6 years, 5 months ago.

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    Profile photo of fxk

    Hi folks,
    Seems with the new version of the firmware, a new problem developed – just checking whether anyone else is seeing it.

    I was plugging/unplugging a condenser mic on a channel with phantom power turned on. I heard a pop, and thought I had a brain fart not muting the channel. Did not think anything about it until later.

    I was troubleshooting another channel where I was having a problem with a condenser. Maybe the cable. So I went to swap the cable. Pop. Checked the mute. Channel muted. Plugged in a new cable. Pop. What? One more time watching the board – disconnect. Pop. All channel first meter lights (even empty channels) lit briefly. Plug back in – Same same. Meter lights, and an audible pop.

    If I turn off the phantom, everything is fine.

    Anyone else seeing anything similar?


    Profile photo of Andreas

    Just don’t plug in components with Phantom Power enganged (could also kill your equipment, too lazy to explain again, so check Wikipedia).
    The transient generated may also be noticed on other channels sharing the internal phantom supply, don’t think this is new or strange.

    Profile photo of David Haughton
    David Haughton

    @kxrf Hi Frank, please send us an email with your serial number to support@allen-heath.com and we will do some investigating for you.

    Profile photo of fxk

    Email sent.

    Profile photo of PGDH

    I have a QU16 running 1.90 with almost the same problem:

    When I plug some condenser microphones (e.g. Rode NT1, Superlux S125, Behringer ECM8000) into a channel with 48V already enabled, I get a thump on all outputs (even if they are muted), and all input channels show a transient peak. However, this does not happen with an AKG C1000 or my active DI boxes.

    Of course, I see a peak on the channel in question when I plug anything in or out, but I do not expect to see anything on any other input channels (they don’t even have 48V enabled), or on the output channels.

    I’m not sure if this only started happening after a firmware upgrade. I know how phantom power works, and the risks associated with hot plugging sources. However, I have not had this issue with other digital mixers (e.g. Behringer X32).

    Profile photo of fxk

    A&H got back to me – apparently their early versions of the mixer exhibited this behavior, and more recent versions have been changed so that does not happen. I guess I got old stock…

    A&H offered a solution – to have A&H US or an authorized repair center apply some kind of “optional modification” to my mixer – at my expense – NOT a warranty repair, as there is nothing actually wrong, and as they maintain their position on not hot-plugging recommendation. A bit absurd, but I do not have the energy to fight city hall.

    I have not taken the mixer in for the modification. I’m hoping the next SW release will resolve the problem. I would revert to an older version of the firmware where it was NOT a problem, but alas, there is no way to revert to an older version of the app on the iPad. Stuck between a rock (Apple) and a hard place (A&H). (sigh)

    The good news is it does not happen when I use the AB168, so I do have a half-decent workaround.

    Profile photo of steelex1

    I pointed this issue out last year to A&H and was told about the issue – the response was ‘we do not advise’ hot plugging etc..
    Ok, so I pointed out when shutting down the desk, there was the same pop over the main P.A. and mons. – I don’t have this issue with iLive for example. As always, muting the outputs, surely no sound – pops, bumps etc, should not be apparent. It is obvious there is voltage present even if a mute is activated and with the phantom debate.
    I was told there was a fix, however the desk warranty had expired and it would be a cost implication to myself..
    …so there is a fix they’ve admitted to that does solve the issue – however not with any firmware release.

    Profile photo of airickess

    So, steelex1, you’re turning off your console while the speakers are still powered up?

    Profile photo of Rawdealad

    Got the same issue with condenser mics.

    Really frustrating when you’re trying to work fast and ot happy that some are disadvantaged because we were early to the QU party.

    Any work around yet?



    Profile photo of fxk

    Maybe switch to a “special scene” that has phantom off, then switch to the preset scene with phantom.

    Lately, I’ve been using the AB168 digital snake – and with the snake connected, no problem at all.
    Of course, when I go back to analog snake, I get caught with my pants down (figuratively). They also suggest turning phantom off, then back on after patch. How long would that take with the built in delay to turn phantom on or off…

    Personally I believe this is a despicable way to treat their customers – “yeah, we got a fix, but you have to pay for it. Tough beans to the early adopters.

    That, and the refusal of A&H to provide an offline editor puts me in a position where I would like to get a QPac, but I fear that would be just throwing good money after bad. I got a really good deal on the AB168, so I’m kind of stuck – selling off and buying something else with digital snake, and an offline editor financially does not make sense.

    Heck, someone here on the board says he’s developed an offline editor, but can’t figure how the checksum works. Maybe it’s wishful thinking, and maybe I should be more skeptical, but it would be nice if A&H would consult with this guy and test and help out.

    Makes me wish I had bought Soundcraft.

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