Allen & Heath CQ desks

[Chienmortbb]

On 18/01/2026 at 20:30, Woodinblack said:

 

Like if you have a number of cables running together, he found that having a power cable and an audio cable running next to each other. But that seems not that likely

Audio cables and mains cables running side by side are deemed a bad idea the can cross each other at an angle, but it does effectively mean you have a long aerial from a transmitter running in close proximity to the receiving aerial of the audio input. 

 

There are a few cables that run a balanced cable and a mains cable in the same bundle, Andertons do one, but I cannot find the link. Sommer also do one,

Sommer DMX/Power or Audio and Power Cable. I may get some of the Sommer one to try but at almost €14 per metre excluding VAT, Duties and shipping costs....

[Phil Starr]

That's a very strange noise. I don't think it is a cable. It's not clear from the pic what inputs you have to the mixer. The Zoom seems to be on, was that connected to anything? I've had strange noises (nothing like that though) from my Zoom when the batteries are flat. It sounds to me like something entirely separate from your sound system something mechanical like a relay chattering, maybe on a freezer/washing machine or anything really. It could even be in  a neighbours house. That interfeence can either feed into your system from the mains or by radio waves. 

 

Anyway the first thing to do would be to disconnect everything from the mixer when you aren't using it and see if it ever makes the noise with everything disconnected. If it is fine at least you will be reassured it's your house and won't happen at a gig. Then reintroduce one thing at a time to see if any one connection causes the noise. If it recurs then check if it is that source which is faulty or the lead by swapping for a different lead with the same source. Good luck, these intermittent faults are often really hard to track down

[Chienmortbb]

Wise words @Phil Starr. I have seen similar reports on various CQ forums. However these are likely to be from the same person. I can only add to be methodical. For example, the Zoom may or may not be part of the problem and if removing that solve the problem, do not jump to conclusions. Neither box may be at fault, just the two together and/or cable combinations. 
 

Good luck with your detective work. 

[warwickhunt]

Not the same noise but we had a proper b4llache dealing with a pulsing 'noise' through our desk.  We thought we pinned it down to the sax players Zoom effects unit (when disconnected)... only to find that if he was plugged in and one of the guitar Helix was unplugged it went off!  Argh. 

[Al Krow]

Thanks gents - appreciate the input.

 

To clarify although the Zoom was connected, it wasn't actually providing any signal / output at the time of the noise. Similarly the other inputs (PC stereo in and bass via my Boss GX10 pedal) were connected but not in use. The set up had been connected with devices on standby for a couple of hours, whilst I was had been in another room, when the noise went off. Had happened on several previous occasions.

 

Worryingly - it happened on the final two songs of our gig on Saturday night. Unfortunately the unit is now out of the 12 month A&H warranty having been bought as B-stock from Andertons 15 months back, who have a 3 months return policy on B-stock goods.

 

I do otherwise love this A&H desk, not least the UI  - has been a joy to use! So I have (foolishly?) sourced a second hand apparently vgc used A&H CQ12T as a back-up unit, which will allow me to get the CQ18T checked out by a local tech and/or A&H.

 

 

[Woodinblack]

That is a pain, it certainly seems like a power issue rather than an input issue, as it was going on all channels. And you have ruled out the mains in your house as it happened at a gig (unless the gig was in your house?). Does the CQ12T have the same power supply as the CQ18? If so can you try it with that power supply and see if the issue remains, a replacement power supply would be about the cheapest option

[Chienmortbb]

43 minutes ago, Woodinblack said:

That is a pain, it certainly seems like a power issue rather than an input issue, as it was going on all channels. And you have ruled out the mains in your house as it happened at a gig (unless the gig was in your house?). Does the CQ12T have the same power supply as the CQ18? If so can you try it with that power supply and see if the issue remains, a replacement power supply would be about the cheapest option

My old UI16 had a brick power supply, and it was a pain, one of the reasons I went for the CQ20.

[Al Krow]

2 hours ago, Woodinblack said:

That is a pain, it certainly seems like a power issue rather than an input issue, as it was going on all channels. And you have ruled out the mains in your house as it happened at a gig (unless the gig was in your house?). Does the CQ12T have the same power supply as the CQ18? If so can you try it with that power supply and see if the issue remains, a replacement power supply would be about the cheapest option

 

I'm not sure what the neighbours would think about a gig in the basement at full volume, haha!

 

I've got two separate AC adaptors, one that came with the unit by Fidus (made in China) for home use, and a separate one for gigs by Dongguan Lewe (also China). Both are 12V 5A 60W PSUs

 

A&H recommend their spare part: AH-AM12199 PSU, but this seems to be tricky to get hold of?

 

What PSUs are other CQ desk owners using?

 

Edited 18 hours ago by Al Krow

[Woodinblack]

3 hours ago, Chienmortbb said:

My old UI16 had a brick power supply, and it was a pain, one of the reasons I went for the CQ20.

 

Honestly surprised that the CQs have an external power supply, seems a design flaw on something so well made.

[Phil Starr]

20 hours ago, Al Krow said:

Thanks gents - appreciate the input.

 

To clarify although the Zoom was connected, it wasn't actually providing any signal / output at the time of the noise. Similarly the other inputs (PC stereo in and bass via my Boss GX10 pedal) were connected but not in use. The set up had been connected with devices on standby for a couple of hours, whilst I was had been in another room, when the noise went off. Had happened on several previous occasions.

 

Worryingly - it happened on the final two songs of our gig on Saturday night. Unfortunately the unit is now out of the 12 month A&H warranty having been bought as B-stock from Andertons 15 months back, who have a 3 months return policy on B-stock goods.

 

I do otherwise love this A&H desk, not least the UI  - has been a joy to use! So I have (foolishly?) sourced a second hand apparently vgc used A&H CQ12T as a back-up unit, which will allow me to get the CQ18T checked out by a local tech and/or A&H.

 

 

If anything was plugged in and powered up it is providing a signal, that might be just a bit of hiss (noise) but if that device is faulty then it could provide the fault for the desk to amplify into the speakers. You'd have to switch everything off or better still disconnect it to be sure it was the CQ causing the problem. The Zoom appears to be lit up which is one reason why I suspected it, I also know from my duo partners rather random approach to fx that the Zoom can be driven into instability if you come up with fx chains and settings Zoom never dreamed of. 

 

I used to do a lot of repair work when younger and earning my living as a part time sound engineer/speaker builder. Hence my hatred of intermittent faults, they never happen when the tech has the device. I do suspect B-stock as a result. Someone returns something to the shop and it lays around until one of the shop assistants decides to have a look. They run it for 24 hours (ideally) and nothing goes wrong and it becomes B-stock. You run it for a year and the fault doesn't happen, and then it does. It could be the desk but until you try it without anything connected you can't be certain. By all means talk to a tech, if they repair a lot of CQ's there may be a known fault but I'd be running it just conected to the speakers for a couple of days before I took it in. 

 

The spare desk is a great idea, I have a spare M18 in case mine starts playing up and I've transferred my settings to it so it is ready if I ever need it. I'll get my money back if I ever upgrade

 

When it comes to repairs I'm strictly analogue though