BIG Pops When Recalling Scenes

[WaihekeSoundieParticipant]

Few days ago used my QU-16 for the first time live in what was quite a complex show (for me). Loved it..
One thing though – when switching to one of my scenes there were huge pops like you get if you insert a mic into a channel with phantom on.
Big bangs though the PA. The scene was prob switching phantom on to some extra channels. Possibly deactivating on some others.

I installed 1.31 firmware last night and still hear them through headphones when I switch– maybe not so severe but my cans are not nearly as load as that PA was..

Any thoughts..
Thanks

[WaihekeSoundieParticipant]

Actually what I have noticed is that whenever I turn on or turn off the phantom power there is a delayed spike, a loud hiss and then an other delayed spike.. it almost pushes the level into the red.. you can see it in the meter but not hear it if the mute is on.

I have also noticed that if I connect or disconnect a mic to a channel with phantom on I get a huge spike whether muted or not…
I am running v1.31

Guess my learnings are
a) don’t connect or disconnect mics unless phantom is off
b) always mute before turning phantom on or off

Note: Because a scene change can turn phantom on and off
c) before you scene change make sure that you mute all channels affected by phantom- (a mute group on all channels (except your continuity channels)) does well BUT
d) also note you have to set a Global Filters to retain your mutes and your mute group masters otherwise the new scene may remove them as it switches and big pop again.

Bit fiddly but seems to work for me.
Appols – this prob should have gone in the troubleshooting section eh..

[MartinWParticipant]

I think I’ve read that this is a known issue.
Hopefully it will be sorted in a future firmware update.

[WaihekeSoundieParticipant]

Yes, I see that now but I might say that there seem to be a couple of issues here:
a) horribly loud pops when a mic is physically connected / disconnected with PP on;
b) lesser pops and hiss (depending on channel gain) when I turn PP on and off (with mic connected or not).

There seemed some debate whether these issues are fixed at 1.31. They are not (on my desk anyway).

And what I found (first time out and rather publically) is that b) above can happen when you change scenes. That caught me out. So you need to mute PP channels that are on in the leaving scene OR being turned on by the new scene. So apply an across the board mute group and keep the mutes safe with filters on during scene changes if you have any PP on anywhere.

This is prob what everyone does anyway but I’m a total newbie to digital mixers and these things just aren’t written down.

I should say that I LOVE my QU 16.. it is really cool balance of features and simplicity and it sounds fantastic 🙂

[GR-PDXParticipant]

I agree that this is a problem, but I am struggling to figure out a scenario where I would turn phantom off for one scene but on in another during a show, unless I were also changing mics between scenes?

[WaihekeSoundieParticipant]

Well the way this worked out for me was 5 acts unknown to me turned up for sound checks. Band 3 about 1/2 way through sound check turned out needed a bunch of phantom for their drums on channels not used in any prior band scene so phantom gets set and band 5 later swapped out a passive DI on a channel I had for Acc guitar in Band 1 with a DI requiring phantom on same channel so I engaged phantom in that scene too. As the bands came on things get unplugged and re-plugged and I increment the scenes. Happens.

Quietly next time 🙂

[GR-PDXParticipant]

Yeah, I get that. I guess I wouldn’t have had the presence of mind to use separate scenes for that, and would have just muted everything between acts.

[WaihekeSoundieParticipant]

Yeh, but I had 17 multi-instrumentalists in 5 acts and drums– (about 40 channels on an analog desk) and all wanted to be soundchecked– 40 into 16 is a lot of channel re-use– scenes totally came into their own for this 🙂

Course you can’t really stop the fiddle player plugging into the Banjo DI or the main vocalist taking mic 4 instead of 3 because the bass player has suddenly decided to have a wee sing. But scenes totally helped:)

[GCumbeeParticipant]

I have not tried this but assuming it is a real problem as it sounds it seems like part of the scene change routine of the firmware would be to mute all channels then un mute them when the scene loads. This takes place pretty fast so not sure how the DC would act. Might still get a pop or trailing edge of one.

I don’t recall this happening on GLD’s. Will have to test that one. It has not been mentioned I don’t think.

Just a thought for next firmware upgrade.

[WaihekeSoundieParticipant]

Can see why you might suggest that but I might say that on my desk there is a considerable lag between the PP turning on /off and the pair of voltage spikes.. turning off it is seconds before the first spike- perhaps 3 secs.
Maybe my new QU has a h/w fault?

[GR-PDXParticipant]

If the fault you’re thinking of is the lag for phantom power to be applied, mine has a 1-2second rampup for that as well, whether or not a mic is plugged in. When I first got the desk, this struck me as being potentially an artificial delay, maybe put there so you had a chance to mute before the big spike hit as phantom actually came on. But maybe there is a good hardware reason to ramp up that slow.

[WaihekeSoundieParticipant]

Thanks for confirming it is not just my unit that has this lag.
The huge pop on plugging / unplugging when phantom engaged can be fixed with a H/W return to base eh. That sounds like a bit of a mission though. Has it been establish whether A&H pay for the return? Think they prob should but is there a precedent?

Andy

[GR-PDXParticipant]

I just did some experimenting on my board.

– plugging a dynamic mic in with everything muted doesn’t result in any issues, even when phantom is on that channel.
– plugging in a condenser on a channel with phantom on results in a very loud pop, and literally every channel shows signal clipping as that happens, not just the channel with the mic plugged in. If the master is also muted, it’s minimal.
– turning phantom off and on I with a condenser plugged in results in little sound as long as things are muted.

So the interesting thing is in plugging in a condenser to a phantom-on channel. That is going to create some problems. And it is really odd that every channel is affected.

[GCumbeeParticipant]

No recent discussion on this problem. I did some tests today. It is pretty ugly when changing scenes. What if any final solution has been offered on this?

[WaihekeSoundieParticipant]

I did read somewhere that there was a hardware fix to the bang when plugging / unplugging with PP engaged.. but would mean sending back to UK (from NZ) and who would pay? Is there a policy or precedent for this?

But regarding the loud pops on switching scenes when PP turned On or Off — I will know to set mute groups with global filters before scene changes when I can but it won’t suit every case I’m sure..
So I would be keen to hear more on this..

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