Qu-24 and Qu-SB audio problem

Hello!

I have a big problem with the audio on my mixers. It makes static noise, out of nowhere. Let me explain.

I have those 2 mixers, QU-24 and QU-SB. The QU-24 mixer, i use it for main elements, such as the microphones for the person who speak, for actual audio speakers, and to broadcast the audio through a PC for OBS. All good so far. And the QU-SB i use it for microphones to sing, instrumentals, and portable speakers. And sometimes, I get the audio form the SB and link it to the QU-24, to stream the audio that is playing on the SB, to the Qu-24. It was all working just fine, with no issues. But suddendly, I started to make really loud static noise.

First I thought it’s the cable, and I changed it. The problem still occurs. I’ve tried some headphones, and a speaker directly to the output port on the SB, and the problem is gone. I’ve tested my phone, to play something on the QU-24, the audio is ok. But when I connect the 2 mixers together… Static noise…

As I change the lenght of the cable, the problem fades away. But it’s still there. I’ve tried different adapters, a straight cable… The mono and stereo jack, individually… It’s still there. I even bought a DI unit, and the problem stil persist.

The way I linked my two mixeres, was through the headphones out port on the SB mixer. And the input ST2 on QU-24. Ain’t the best way, I know. But now, every out port does this.

Any idea what could it be and how I can fix it? Or how I should troubleshoot it? Cause I tried almost everything, and nothing.

My money is on a ground loop of sorts. Make sure you power both from the same outlet, make sure your grounds are ok. Maybe even use a ground lift between them.

Good luck !

Giga

"The way I linked my two mixeres, was through the headphones out port on the SB mixer. And the input ST2 on QU-24. Ain’t the best way, I know. But now, every out port does this. "

That got my attention!!!

Do you not have any other outputs on the QUSB to connect to an input on the QU24?
Also the headphone is a stereo tip ring sleeve output and you are connecting that to a
mono balanced input, those two will not correctly work together?
Now if you are taking a TRS cable that breaks out into two mono 1/4 plugs and plugging them into the ST2 inputs that would work…at least better, still not the best way.

Using the matrix output could be an option or a mix set to post fade and brought up on all the input channels.

You may need transformer isolation between the two mixers.

Did you try ST1 and ST3 on the QU-24? Sounds like a dirty or loose connection on ST2.

You had mentioned using a DI, what input on the Qu24 did you plug that into?
With the DI were you still using the headphone out on the QuSB?
Did the DI have a ground lift switch?