My CQ18T is possessed. FBA has a mind of its own. Any ideas?

CQ CQ Troubleshooting
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::EDIT 2:: It seems I did not find the source of the problem. See the next post for details and a screenshot.

::EDIT:: I believe I found the source of the problem. When using both the iPad CQ Mixpad app and the console’s controls, the FBA Detect mode does not sync between devices. For example, if I’m on the FBA screen on both devices and I change the Detect mode from Fixed to Live, or vice versa on one device, the change does not sync on the other device. Say I have both the iPad and the console showing Fixed mode - if I change it to Live mode on one device, it stays in Fixed mode on the other. So if I’m using the mixer’s own display and an iPad to control the mixer, there is no way to know accurately whether the FBA mode is set to Fixed or Live mode. I confirmed this problem this morning while troubleshooting at home.

::Original post below::

I had a gig last night and came very close to throwing my CQ18T in a pond. The main issues were with the FBA and also the CQ Mixpad app. I’m not sure if they are related.

The problem only happened on the Main output. There were no issues with the Aux outputs. During setup I configured the FBA as I normally do. I started with no filters set, then I set the detection mode to Fixed and turned off Hold. I configured 12 fixed filters like I normally do, watching the Adjust screen to make sure it was really setting 12 Fixed filters. When all 12 were set I switched the mode to Live. On the console I then switched to the Fader screen.

I opened up CQ Mixpad on my iPad and went to the Output screen and started monitoring the FBA.

Everything started off fine but at some point toward the end of the first set I noticed that out of the blue, the FBA had scooped out a steep canyon between roughly 700Hz and 5K, give or take. I’ve seen this before when I left the FBA in Fixed mode so I double and triple checked that it was in Live mode. It was.

It was as if it completely ignored the Live setting and decided to switch itself to Fixed mode where it could adjust or reuse the Fixed filters.

During the break I had to go to each filter and adjust them manually and even deleted/reset a few because it was so messed up. We already had a crowd and I couldn’t run the FBA again from scratch so I just adjusted the filters’ width and depth as best as I could.

Second set starts fine, then halfway into it, the same thing happens. As I’m watching the FBA on the iPad, the Fixed filters would be adjusting themselves constantly, sometimes deleting themselves, other times being reused, sometimes just adjusting the depth or width like it can sometimes do when initially setting up the FBA in Fixed mode.

Again I checked the mode to make sure it was in Live mode, where the Fixed filters are supposed to stay FIXED and not constantly readjusting themselves.

Now here’s where it gets suspicious. Eventually I had the same FBA screen displaying on the app and on the console. I had the RTA on in the FBA screen and I noticed that when I enabled it on the app, it would turn off on the console, and vice versa. Whatever I did on the app or the console, the opposite would happen on the other side. Can the RTA not be enabled on the app and the console at the same time and if you enable it on one, it automatically turns off on the other? Or was it really out of sync?

If the app and the console were out of sync, that might explain whey I could set the Filter mode to Live (I toggled it back and forth a couple of times to make sure it was on Live mode) but the filters would continue to behave as if the FBA was set to Fixed mode although sometimes the depth on some of the filters would get shallower and eventually the filter would reset, which is what happens in Live mode, but these filters were configured as Fixed.

I kept going back and forth between the app and the console and started wondering if it’s possible that when I set the filter mode to Live on one, it would switch to Fixed on the other and Fixed mode would take precedence? Eventually I disconnected the tablet but that didn’t help so I’m not sure if the tablet/Mixpad app was the problem.

I started the night with 12 Fixed filters and by the end of the night 7 of them had disappeared and only 5 filters were left configured. The mixer did that all on its own even though initially there were 12 fixed filters and it was set to Live mode and the filters that disappeared were configured as Fixed filters. And of course all the other disasters that happened in the middle of the sets where it would scoop out most of the primary frequencies on its own and randomly adjust preconfigured Fixed filters when it was in Live mode.

Any ideas what’s going on? This is definitely concerning. When I got home last night I read and re-read the section in the manual about the FBA and it’s very clear that if you initially set however many Fixed filters you want with the FBA in Fixed mode, then you switch to Live mode, the Fixed filters are supposed to remain the way they were set and only the remaining unconfigured filters will be used as Live filters and will automatically adjust as needed. But the Fixed ones should stay fixed.

Or…am I still not understanding how the FBA is supposed to work? That said, I had the FBA on the Aux outputs set up the same way and did not have any issues, and I’ve been using the mixer for months now without running into this problem.

BTW, firmware version is 1.2.2r4248. iPad app version is 1.2.3.

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Ok, I’m ready to toss this thing and write it off as an expensive loss unless someone can figure this out, even if it’s user error.

Today I had another gig and this time I did not use the iPad, I didn’t even have it. I ran everything from the console.

So what happened? I rang out the monitor with the FBA. I started off by doing a reset on the FBA assigned to Aux 1 (monitor). I then set the Detect mode to Fixed and turned off Hold. I then unmuted the mics and gradually turned up the level of the Aux output letting it detect feedback and set 12 Fixed filters. I then selected each filter one by one to confirm that they were actually set as Fixed filters. They were. I then set the Detect mode to Live. Per the user manual, this should leave the 12 Fixed filters completely FIXED and leave 4 filters for the mixer to use as needed.

About halfway through the first set I started getting some squeals from the monitor and when I checked the FBA, it had completely deleted/reset several of the filters and I was now down to about 6 Fixed filters. WTF, right?

So during the break between sets I completely reset the FBA and zero’d out all the filters and started again doing exactly what I did the first time. Set 12 Fixed filters while in Fixed mode, then changed it to Live mode.

Gradually through the rest of the gig I kept getting more and more squeals. By the end of the gig after 3 sets, when I checked the FBA, this is what I was left with. Remember, I started with 12 Fixed filters and then set the Detect mode to Live.

CQ18T-FBA
CQ18T-FBA1920×1440 347 KB

So basically, the FBA just did whatever the hell it wanted to and deleted 10 out of 12 filters that were configured as FIXED, even though after setting the 12 Fixed filters I switched the Detect mode to Live so it would leave the Fixed filters alone and have 4 Live filters to work with to automatically catch any squeals, which it didn’t even do that and I kept getting squeals from the monitor throughout the entire gig. Notice the output level is at -8. I had to do that because the FBA wasn’t doing anything.

I am fully willing to admit user error if this is what it is but I don’t think that’s the case. I also don’t recall running into this issue before the last couple of gigs. Coincidentally, I noticed this happening after updating to the newest firmware. I don’t know if that’s related but now I’m wondering if there aren’t some major bugs with this FW.

What I do know is I can’t use the mixer like this and right now I’m sitting here feeling like I wasted $1200 and the time and effort to learn how to use it. Almost feel like I should go back to my Zoom L20 with the annoying outboard rack full of EQs and feedback eliminators. It was a pain to set up and tear down at gigs but it “just worked”, unlike this thing which is pissing me off to no end. For the record, I mix my two bands from the stage while also playing guitar so I can’t be constantly dealing with this in the middle of a song or a set, or even between songs. It looks extremely unprofessional.

So, is this user error or is it not working properly?

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Sorry, I don’t have a CQ and I don’t use any FBA, so this is only theoretical.
But if I understand your FBA correctly, you have to activate HOLD at some point after the detection procedure, otherwise your system will continue to search for new feedback and set the appropriate filters.
Switching to ‘Live’ mode only means that the next filter is recognized as a ‘Live’ filter, not that ‘Fixed’ filters are taboo!
If all Live filters are used up and another feedback is detected, a ‘Fixed’ filter is “stolen,” as A&H calls it in the description.
And since you’re in ‘Live’ mode, this filter now becomes a ‘Live’ filter - and so it goes on.

We don’t know what kind of music you perform, in which critical spaces, with which (perhaps simple?) equipment, but I can hardly imagine a situation in which such extreme feedback could occur continuously.
(Using omnidirectional headsets for heavy metal?)
But it might just be feedback-like sounds you’re creating with your guitar, keyboard, or sustained vocals, which your FBA is constantly trying to remove.

So, in my opinion, you need to activate HOLD at some point after adjusting your settings.

1 Like
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Thanks. I’m in two bands, both are simple 4 and 5 piece cover bands, classic rock, top 40, funk, disco, etc. Nothing unusual, mics are EV ND96 and SM58. Guitar, bass, and keys are run direct into the board.

One band has more feedback problems due to very loud stage volume, small and reflective venues, and a lead singer with a very soft voice. The other band rarely has feedback issues….until yesterday.

Since I got the CQ18T I’ve been using the FBA the exact same way and never had any issues. These particular problems are new.

Sometimes I don’t even set 12 fixed filters, in the band with fewer problems sometimes I’ll set maybe 4 or 5 filters on the mains although I do like to crank the monitors so I do tend to set all 12 fixed filters for that. But yesterday’s gig was the first time I had this problem with this band.

Enabling HOLD stops detection but I like to have the extra Live filters to catch any unwanted squeaks like when the singer kneels down in front of the wedge.

Here is what the manual says about Fixed filters - page 46.

Set the filter Mode to Fixed. This will mean any detected feedback frequencies will have a fixed filter applied (which will remain until manually deleted).

My understanding is that switching to Live mode means no more fixed filters will be applied but it shouldn’t be deleting any Fixed filters that have already been configured. Even if it was stealing filters, it shouldn’t completely wipe out all the filters. BTW, the manual says that Live filters cannot steal Fixed filters, only other Live filters. So it shouldn’t be completely wiping out all of my Fixed filters.

Not to mention, in yesterday’s band, feedback is never that big of a problem that would require just wiping out pretty much the entire FBA. And we have played that same venue a million times using the CQ18T and have never had this problem before.

Something is definitely off with the way the FBA has been working lately and I’m suspecting it started after the latest firmware update.

Oh, not to mention the Detect mode being completely out of sync between the console and the iPad app. For all I know the thing magically switched itself from Live mode to Fixed mode yesterday even though it showed that it was in Live mode.

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But the sentence ends with:
… or if the Feedback Assistant ‘steals’ them.

If ‘Fixed’ filters were to become ‘Live’ filters through stealing, they could disappear after their feedback use:

Live filters … will switch back to being unused filters.

I’m not assuming actual feedback, but rather feedback-like tones.

What confuses me about this whole thing is their sentence:

Note that Live mode filters can only steal other filters already in live mode and Fixed mode filters can steal any filters.

It would be really nice if A&H would explain the situation here.
But in your case, you’ll probably have to contact support separately.

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The way I’m reading it is that Fixed filters cannot become Live filters because Live filters can only steal other Live filters.

I have seen Fixed filters be “stolen” by other Fixed filters while ringing out a room with the detection mode set to Fixed, but I have never seen a Live filter steal a Fixed filter and literally delete it, at least not until the last couple of gigs, if that’s what’s even happening. I just think the FBA is completely borked and malfunctioning.

I did email A&H support regarding the issue of the detection mode not being synced between the console and the iPad app but I haven’t received a reply yet so they don’t know about yesterday’s new disaster, which was probably also happening on Friday’s gig but I just didn’t realize that was part of the problem.

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I don’t know if this is the best approach.
Perhaps it’s better to contact support directly:

https://support.allen-heath.com/hc/en-gb/requests/new?ticket_form_id=360001516878

It should be a new ticket.

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I emailed them at support@allen-heath.com and received a confirmation that a ticket was created.

I just replied to their confirmation email to add the info about yesterday’s problem. I’m pretty sure they are related and the reason the FBA was going nuts on Friday was the same problem I had on Sunday. The Detect mode status not syncing between the console and the iPad app is likely a separate but possibly related issue.

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So I’m not crazy after all. I heard back from A&H and they confirmed that they were able to reproduce the problem and it is a bug. Fixed filters should remain fixed once you switch the mode to Live. I was told that it should be fixed in a future maintenance firmware release.

Hopefully soon…. like I mentioned, this is a pretty major issue for me with one particular band.

3 Likes
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Thank you for sharing this information.
I actually wouldn’t have expected a bug like this.
It’s great that it’s now on the list! :+1:

What I don’t have an explanation for yet is why you can’t manage with 16 (+ 4 PEQs, which you also have) fixed FB frequencies.
Ultimately, this would mean that this band could only be mixed in poor quality or not at all on higher consoles like SQ (and above), since they don’t have any FBA at all.
That would be very strange and so I assume the cause of your problems lies somewhere else.

Also keep in mind that when using your 4 live filters, feedback must first occur for it to be recognized as such.
That would mean that there would always have to be ‘squealing’ during your show so that these filters can even adjust anything.
As a listener, I really wouldn’t like that.

If I were you, I would consult a specialist who would work together with you and the band to identify and resolve the problem.
All the best for that!

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Like I mentioned, I often have to mix in less than ideal conditions. Small stages, highly reflective rooms, unreasonably loud stage volume that I can’t do anything about, singer with a very soft voice who stands about 1’ in front of the very loud drummer, mains not far enough in front and too close to the vocal mics, and the list goes on and on and on.

When the FBA works fine I do not have any issues. The frequencies it notches out tend to be very narrow so it’s not like I’m carving out a huge valley.

As for leaving the 4 live filters, yes, I understand that in order for these to kick in, feedback needs to happen. But when I ring out the room I am usually able to get rid of all of the offending frequencies beforehand so it’s rare that a live filter gets activated. But it’s still nice to have to catch the occasional squeal, like the example I gave of the singer kneeling down in front of the monitor.

So to answer the question, yes, I manage just fine with 16 Fixed filters and the PEQ, which is set to apply only very minor cuts or boosts to certain frequencies. But when the FBA malfunctions as it has been doing, that’s when the problems happen.

With my other band, like I mentioned, it’s much less of a problem because we have a lower stage volume and the singer’s voice is naturally louder so the mic gain and output level can be set much lower.

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So it remains a fact that it is currently impossible to mix the first band under the conditions described with an SQ or Avantis, but only with a CQ or a QU 2.0.

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Very few things are impossible. I used to mix that band with a Zoom L-12 and an L-20 but I also had an outboard dBx AFS2 and a couple of GEQs. I could mix the band with a $50 Behringer mixer with 4 XLR inputs if I had to, but the CQ’s combination of features makes it pretty much the perfect mixer for my needs, as long as those features actually work.

But the fact does remain that you can’t beat the laws of physics. The loudest sound at the mic wins and if the vocal mic is right in front of cymbals hitting 125db and there is no way to change that, and the speakers are not placed in front of the vocal mics, among other limitations, there are still some things I can do to help reduce feedback but there’s only so much that can be done. I have measured our stage volume at 125db, and that’s about 6 feet away from the cymbals and without my guitar. A feedback assistant like the one built into the CQ or an external one like a dBX AFS2 is a very useful tool to have in this situation.

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I just had a dbx afs2 that I returned to Sweetwater for a refund after getting my Qu-5. Even in my extra live (much room reverb) Church Sanctuary, this would have been redundant. Besides we were refunded I suppose the full amount because we bought the Qu-5 and AB168. So the $500 or so refund was easy for them to swallow in light of the estimated $4,000 Allen and Heath equipment bill.

FWIW my Qu-5 feedback suppression takes all 16 filters every service. As mentioned elsewhere, we will need to do some acoustic treatment of about 320 sq. ft. to get to the pro target of 1.88 RT60. This ought to lessen the feedback suppression load. No mistake though, it’s fast acting. I barely hear the feedback and it’s gone.

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Yeah, I haven’t used the AFS2 since I got the CQ18T. Its internal feedback assistant works very well with the exception of the not insignificant bug it has.

At my last gig I set all 12 Fixed filters on the mains, switched it to live but forget to enable Hold, so once again the bug showed up, it “repurposed” some of the Fixed filters, then converted them to Live filters which then disappeared so I ended up with a couple of unwelcome squeaks in the last set. I’m very eagerly looking forward to the day A&H releases the firmware that fixes this.

Other than this problem the FBA is excellent. I think the AFS2 is a little better but that’s to be expected from a dedicated unit that only does one thing vs one feature on a mixer that does a whole bunch of things. Plus the CQ makes a FBA available on every single output which to me is a huge benefit since I can now have a feedback eliminator on the mains and all the monitors. And at some gigs I do use all of the aux outputs and being able to dial out the feedback on all of them is really helpful.

As a complete package the CQ18T is fantastic even taking into account the potential improvements they can still make.

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On my Qu-5, I’m only needing 2 instances of FBA. I have an instance for one piano monitor mix and then for the FOH. So far due to my extra reverb sanctuary situation, I’ve ran mine in fixed.

My old Soundcraft Ui16 had dbx afs2 built-in but it was limited to 16 filters like my Qu-5. The dbx afs2 external rack unit has 24 stereo filters or 24 pairs in dual mono. I could assign x number fixed with the rest in live “search and destroy”. Very effective for my needs. But redundant.