Random spikes on FX1-4 send & return and MTX3-4

[ftmusicParticipant]

Hi all. I’ll tell you the problem I’m having with the Qu-24 mixer. After a year I still haven’t solved it!
About a year ago, my Qu-24 mixer started emitting random spikes on channels FX1 Ret, FX2 Ret, FX3 Ret, FX4 Ret, FX1 Send, FX2 Send, FX3 Send, FX4 Send, MTX3-4 Master. I have a video from May 23, 2022 of which I am attaching a screenshot. To solve this problem, I first contacted Allen & Heat Support and a kind Product Support Engineer gave me instructions to do some tests, but we did not solve the problem. So I got to contact an Allen & Heat authorized service center which, after some time, identified the problem in the Audio Board, proposing a replacement. I thought about it for some time and I accepted the estimate of about 900€ for the replacement of the Audio Board. From the acceptance of the estimate to the delivery of the repaired mixer, 6 months have passed due to problems with the supply of spare parts. I finally brought the Qu-24 mixer back to the studio on March 27, 2023. For about a month, it worked fine, but, after 1 month and 3 days, on April 30, 2023, the exact same problem occurred as a year ago . I made a new video, of which I attach a scrrenshot. As you can see, the spikes are on the exact same channels. I immediately notified the Allen & Heat authorized service center who replaced the Audio Board, since the repair has a 3-month warranty. I ask other Qu-24 users if they have had this problem. I’m quite desperate, because I lost several months of work because of this problem and, despite having spent 900€ to solve it, I find myself back to square one after a year. What should I do?

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[ftmusicParticipant]

I am still waiting for a reply…

[Mike CParticipant]

If you mute the sends and returns do you still get the noise on the FX channels?

Just making sure you have not created a feedback loop by having an FX return with it’s own FX send turned up causing a feedback loop.

[ftmusicParticipant]

On Qu-24 you can’t route a return channel to a send channel making a feedback loop. Simply there is not such a possibility.

[Mike CParticipant]

Yes you can send a FX return back into itself by bringing up the FX send level on
the FX return channel, you do need to have the assign button turned on the FX return channel.
On the default set up the FX return is not assigned to it’s FX send.

Post pictures of the surface with each FX button selected or the routing screens of each
FX return selected.

[Rafael A&HModerator]

Hello @ftmusic,

Have you perform a Hard Reset on the unit to bring it back to factory state?
This will help to guarantee that it is not being caused to any operational error, such as what Mike C suggests.

Is your unit in the latest Firmware? If not, please update it. (Latest: V1.97)

As a side note, as Mike C mentioned, yes it is possible to send an FX Return into a send. This is mostly used to send FX back to a monitor mix, for example.
If not careful, you might end up sending the FX Return into its same send, creating the loop the Mike mentions.
By default, the FX Return will not be assigned into its same Send channel, you would have to assign this manually using the ‘Assign’ key.

If after the Firmware update and Hard Reset you still have the same problems, please contact us once more to Support@allen-heath.com and we’ll be happy to follow up on this.
Thank you,
Rafael

[ftmusicParticipant]

Thank you for the clarification. It’s true, I confirm that on the Qu-24 you can assign an FX return to any of the FX sends and so it’s possible to generate a feedback loop. In my case (and I’ve verified that this is so correctly set by default after an hard reset) the returns are not assigned to sends that have the same number (eg FX1 Ret is not assigned to FX1 Send). So the random signal spikes on my Qu-24 can’t be caused by that feedback. Soon the A&H authorized service center will work again on the problem. I’ll keep you up-to-date.

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