ZED10FX High Pitched Noise or Hiss with USB connection

[volounteer]

@Mike

If what you just said is true then just do not connect the usb to a PC and activate audio through it.
I am still thinking your problem is the stuff you have attached to the Qu and not the Qu itself.
Are you connecting and activating the Qu USB to the PC using usb2.0? or does it have a later version??

[Mike]

I have to use the USB because the USB is what sends the mic, guitar and backing track audio to Zoom. In Zoom, I select the ZED as the “microphone”
What is a Qu ?

[volounteer]

@Mike
Sorry for the typo.
Qu is a bigger version of mixer between Z and the SQs
so replace Qu with Z10 in the comment above and it will still apply.

You still did not tell us if the PC is usb2.0 or not.
USB2 is rock solid with AH mixers. usb3 has issues.

[Mike]

Sorry, missed that. I’m not actually sure. I know the desktop machine has both USB 2.0 and 3.0 ports so I don’t know what type of port it’s plugged into atm, but I will check that.
I believe however, the laptop I troubleshooted with is only USB 2.0, but I’ll double check shortly.

[Mike]

When I plug the (ferrite bead) USB into the laptop, there is no noise at all when USB is activated as an input. BUT, when I plug into ST2 (from the laptop’s headphone out), the noise appears. Additionally, the volume of the noise is controlled by the gain on ST2.

Next, I had to drag the audio rack over so that the ferrite bead USB cable would reach the computer. I plugged it into a USB (2.0) port, and the noise was present. ST2 had no effect whatsoever on the noise in this case like it did on the laptop. I could unplug ST2 altogether and the noise is still there.

SO, my conclusion, still without a resolution here:

USB to laptop = no noise
USB to laptop and laptop audio to ST2 = noise

USB to desktop = noise (whether or not laptop audio is plugged into ST2)

Also, USB 2.0 or 3.0 port made no difference.

[volounteer]

@Mike

I see the data saying the laptop out is the problem, as is the desktop, as it works with laptop fine without headphone out to ST2.
There is a whole thread on usb noise. 20 pages of it.

Digital noise when streaming audio via USB-B.

You might find some clues there but I suspect that you will need to use an audio interface instead of usb.

[KeithJ A&H]

@Mike –

The “Different grounding between the connected equipment” is a relative thing, i.e. it might require a combination of things to be connected for there to be a problem (as you have found with the laptop output). So try physically disconnecting everything except the USB <-> computer/laptop first, then connecting things individually to figure out which two (or more) create the noise.

Once you have found where the difference is, you can either use a DI box if the guitar (or any pedals?) is causing the difference or a line level matching transformer (often referred to as a ‘hum eliminator’ or similar) for any line level signals such as that from the laptop analogue output. If you can’t have a common ground, the aim with this is to isolate everything electronically whilst still have an audio connection.

I noticed from the picture that you have around +15dB on the trim for both ST channels – this seems a lot, so make sure the outputs at the sources for those channels is actually line level and turned up!
Note also that although you can get away with it 90% of the time, a headphone output is not the same thing as a line level output. A headphone output from a laptop is intended for a ‘floating’ pair of headphones rather than connection to another piece of equipment like a (grounded) mixer.

You’re welcome to contact us about this directly using https://support.allen-heath.com too.

Thanks,
Keith.

[KeithJ A&H]

@volounteer –

Unfortunately that link is to a discussion on Qu/SQ which uses a completely different USB connection and is not at all the same noise as being discussed here.
As already stated, this issue has nothing to do with software (or maybe even the ZED!) and is a case of digital noise making its way into the analogue circuitry.

Cheers,
Keith.

[Mike]

Keith, I had already isolated the noise directly to the USB. i.e., with only the USB connected to the mixer and to the desktop computer, the noise is heard (through speakers, or through the headphones)

It’s only when I connect the laptop (which is just for troubleshooting) to the USB and the ST2 from the laptop’s headphones out that the noise appears and is directly attributable to that ST2 from the laptop.

But with the desktop the same noise is heard with or without ST2 connected.

The first ST channel is audio output from a MIDI player. To get correct input signal level to the mixer, I have to raise it as shown, and yes they are both turned up at the sources.

As far as the headphone output on the laptop, there are no other audio outputs on the laptop, so I think I need to use that.

If I submit a ticket, I should just link to this thread I suppose?

[volounteer]

@KeithJ A&H

Thanks for clarifying.
My bad for presuming that the Z10 had the same usb circuits at Qu and SQ.

I would still look at the pcs and other gear being the cause of the problem before the z10.

And I would still think that an audio interface would be easier than trying to find the usb related problems.

[Mike]

What do you mean by “audio interface” exactly?

[volounteer]

@mike

audio interface connects audio devices to the pc

our church uses this to go from mixer to pc for our livestream (they considered usb but decided against it)
https://www.presonus.com/products/AudioBox-iTwo

We use the green audio output from the PC to feed sound for ppts and videos with no problem
but we do not loop back to the pc with other things at the same time like you seem to do

[Mike]

Are you saying, you go out from the mixer’s Main XLR outs into this device and then from that device into the PC?
If not via USB, how does it connect to the PC so that the PC can see it as an input device in Zoom for example?

[KeithJ A&H]

@Mike – That’s a great plan otherwise one of us will probably ask you all the same questions again!

@volounteer – It’s logical to think they might be the same or very similar, so apologies if that sounded blunt, I just didn’t want Mike to dive into looking at drivers/software unnecessarily.

[Mike]

Keith, right, certainly don’t want to go through all the same troubleshooting and such again.. Submitted ticket #CKH-815-60891

[Author]

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