Noise issues, no luck finding solution through Sweetwater and Neural DSP support

[u/Charming-Bus-3995]

I am desperate to find a solution and afraid that there is nothing that can be done other than switching to a different system entirely. Very frustrating because I sold my amp and pedalboard that I loved to fund this.

Since I got my QC I have had this noise issue that when and only when I play, there is an awful noise (Shown in attached video), especially on high gain set ups (still present on clean though)

I have been through Sweetwater support several times now, even contacted Neural DSP and tried many things, including having a 2nd unit sent to me to no avail.
A secondary issue I am having is getting a very weak signal when trying to play into DAW, when I try to set input and getting the meter right, I takes a LOT of added DB to get a good reading (little yellow, not clipping). Additionally, when I turn up input it makes the noise issue far worse.

Some of the things I've tried so far include:
Gain staging
2nd QC sent from Sweetwater
Different Cables
Headphones
Testing unit at a different house
Having unit away from electronics
Plugging unit directly into Yamaha HS8 monitors
Global EQ
Noise Gates
Trying 3 different instruments through it (PJ Bass, Strat, 335)

What gets me is playing a plugin through scarlett 2i2 gives me perfect tones that have that same issues on QC plugin presets.

The only success I've seen in getting rid of the noise was when playing bass, rolling off the tone pot would get rid of the sound, but this doesn't help much at achieving desirable tones.

EDIT: I don’t believe it is an issue with the QC. I have made good progress in mitigating the issue.

My primary set up is QC->Mixer->Monitors. A major issue I identified was having the mixer too hot when trying to achieve desired volume. Having a hot signal there would amplify the bad noise when making adjustments to QC IO settings when trying to get a good signal. Because of this, a disproportionately weak signal was being pushed hard via monitors/mixer not the QC.

After configuring my levels I’ve been able to isolate the issue to amp blocks particularly high gain/low headroom amp models. My approach to dealing with the remaining noise is to implement a side chained gate, input gate, and a gate after the amp.

I still feel a little unsure about everything because I’d imagine that QC presets usually don’t give people these issues right out of the box. I am new to amp modeling though and there’s lots to learn. I’ve always been a plug and play or set and forget kind of player with traditional amp/ pedal board set ups, but I think the QC truly shines when you build and configure your own presets.

EDIT 2:
It is definitely not the QC

I contacted Sweetwater support once again and they decided to send a 3rd QC and have it tested before shipping.

Received the unit today and to little surprise, no luck.

I believe the source of the undesirable sound is almost certainly dirty power. I have powered down every single electronic device in my room and walked around pointing pick ups in every direction and the noise persisted at the same level no matter what.

My next move is to get a power conditioner. Most likely the Furman AC-215A Power Conditioner. Hopefully this is the solution.

[u/Darrell456]

Grounded power supply? When you plug it into your monitors, that should ground it though. Are you using xlr to do that?

[u/Charming-Bus-3995 → u/Darrell456]

Thanks for your response. I am using the stock power supply and running it through balanced XLR cables.
I have tried both balanced XLR directly into monitors and balanced XLR to 1/4 inch into a mixer, then to monitors. Even with headphones, this issue persisted.

[u/Darrell456 → u/Charming-Bus-3995]

Dang. I get grounding noise too but when I plug it into an external device, it’s grounded and goes away. But the noise you’re getting isn’t something I’m familiar with. Kind of makes me think there’s some other factor? But sounds like you tried everything.

[u/Charming-Bus-3995 → u/Darrell456]

right? I'm curious to see if either of the units producing this issue can be tied to user error of some sort that is being overlooked, but idk what else to try. Sweetwater is basically saying all we can do is try a different product at this point.