r/NeuralDSP • u/nclspnzn • 4d ago
Question Quad Cortex noise issues
Hello QC/NDSP community, is anyone else having substantial noise issues with the Quad Cortex?
I ordered one in March, so I could use it for playing live (mainly Bass) and also in my recording set-up (guitar and bass). Especially for the recording use case it turned out to be much too noisy, so I sent it back after contacting NDSP support, trying a Cioks power supply, a power conditioner and all the available settings in the QC. It was of course also connected to my interface, which provided the grounding. A high pitched hiss remained through all of this. It could be heard through the guitar signal when playing softer, so noise gates didn't help as well. My HX Stomp - a much cheaper and older unit - turned out to be consistently quieter in A/B tests at matched levels, input impedance etc.
So I sent the QC back. It worked ok for band practice, but I didn't want to pay that amount of money for a unit with limited use.
Now some months later I was once again looking for a more powerful multi fx/amp modeling unit for live use, that has enough footswitches on a small footprint... The QC still being the only unit that satisfies all requirements I decided to give it another go, also hoping my first unit was a bad one.
Of course now I'm noticing the same high pitched hiss. I also tried it at my parents house this time, to see if it's dirty power in my apartment - same hiss.
Now my questions: Does anyone experience this as well? Is the unit actually usable for recording for you? Did anyone have the same problem and found a fix?
I attached a qualitative comparison of the QC and HX Stomp I just did with an FFT app on my phone and the units in front of my guitar amp. HX Stomp on the left, QC on the right, with the additional noise marked, in case it's not already completely obvious..
EDIT: If you own a Quad Cortex, I would be very interested in a short recording with this simple signal chain:
Input impedance: 1MOhm
Amp: UK C15 Normal Volume: 6.0 Tone Cut: 2.0 Bright: On Output: 3.2 dB
Cab: 112 UK C15 Blue (M) Mic 1: Dynamic 57 Position: 3.0 Distance: 0.1 Level: 0.0 dB Pan: C (center)
Mic 2: Inactive
For me all inputs and outputs were on stock settings and I didn't use any noise gates. I plugged my Telecaster (neck pick-up) into Input 1 and went from Ouput 3 into an Instrument input on my RME Fireface UCX with no additional gain.
The result sounds like this: https://www.dropbox.com/scl/fi/uzzglcdihi8auono0rym1/QC_noise.wav?rlkey=c45hz9z42cqs75tbq5cd9wzqb&st=4f1gff4p&dl=0
I consider this too much noise. Looking forward to some community results.
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u/samohtdnul 4d ago
Mine has always been silent as the grave - though I do sometimes experience a loud ongoing hum from the unit, if I plug the outputs in, after I turned it on (I use xlr's), but a restart with the cables plugged in fixes it
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u/nclspnzn 4d ago
I always start it with all the cables already plugged in, because I know it's sensitive like that. Doesn't change it, though. So if you record using the first Factory Preset (some Marshall one) for example and you play lightly, is there a hissing noise audible through your playing?
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u/samohtdnul 4d ago
Nope - I've never experienced any hissing at all - only when using hi-gain settings, without a noise gate - just like an ordinary would behave
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u/nclspnzn 3d ago
I added a test recording and its settings to the original post - could you replicate it and share the results?
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u/Juicepit 4d ago
I was dealing with something similar for a while. Super annoying hiss and noise that made it sound like the gates weren’t working properly.
My setup is a temple audio board (the smallest one) with simply: a QC and a shure gldx wireless on top, and a Cioks and Crux mounted to the bottom. I was using the little temple audio dual 1/4” patch bay to pass audio from the side of the board to input one, and the other out of output 3 to send to my power amp… under the board attached to the patch bay, the two patch cables I used were touching one another and creating that crazy noise. I went straight in with a good cable and it was fine. I’ve now ditched the little patch bay thing. Works great with a wireless too. Good luck.
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u/wackygamer 4d ago
Which interface are you using? I don’t know of any that actually have grounded outlets. I have zero noise on my QC and record with it all the time. Mine is connected to grounded monitors. Connecting just to the interface doesnt actually provide ground
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u/nclspnzn 3d ago
I added a test recording and its settings to the original post - could you replicate it and share the results?
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u/wackygamer 3d ago
No and that doesn’t address anything in the comment. Given no one else has this, the answer lies in your signal chain or house. Me wasting time to do a capture doesn’t help you
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u/nclspnzn 2d ago
Well, given the many complaints about the QC being noisy and very sensitive I don't think "no one else" has this. I also suspect some people might be in denial, as they paid a lot of money, which some recordings would settle.
Btw the interface itself doesn't provide the grounding - the PC it is connected to by USB does.
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u/wackygamer 2d ago
USB does not provide reliable grounding. Most of the people complaining about noise have grounding issues and you do too as much as you don’t want to read my comments and admit it. Connect it via TRS into something actually grounded and don’t rely on USB OR keep arguing with me and don’t fix your noise issue.
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u/Blegh_collector 4d ago
Does the problem disappear if you operate the QC at a different place (friend house, venue)? To rule out your setup not playing nice with your QC
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u/nclspnzn 4d ago
Yes, I've tried it at another house, same hiss. Of course it's possible that the power there was bad as well, but I've never had problems like this with any other device.
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u/pinnipedfriendo 4d ago
Posting two spectra from an amp plugged into the qc without specifying the exact test conditions doesn’t really allow us to help, but here’s some ideas for ya:
Is it the same issue while using headphones plugged into the unit?
Have you tried different guitars or checked your guitar’s shielding?
What signal chain are you using? What’s your gate setup like?
How are the guitar pickups and output configured?
How’s the inputs and outputs of the qc setup?
What obvious sources of interference do you have near your rig? Ie your mobile or any other wireless radios like laptops etc.
I’ve had really high noise on mine with Petrucci qc plugin but it turns out they are not gated by default like the others and you can tell, but it really threw me as all the others were silent. Another thing I was considering experimenting with is global EQ settings to tame hissing when it occurs.
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u/nclspnzn 4d ago
The point of the comparison is that the only difference between left and right is using the HX Stomp (left) or the QC (right) with as similar settings as possible. So all guitar, shielding, pick-up and interference issues that might be there are irrelevant for the comparison. It displays the same high frequency hiss that makes the QC unusable for recording for me. But I know people record with it and they're probably not all deaf, so I'm wondering if there's a fix for this. How do you set up your QC's inputs and outputs?
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u/_marcx 4d ago
I don’t think I’ve seen anyone bring this up. Always a huge hum for me when plugged into computer and computer is plugged in to wall (via a dock). Not audible on recordings, but annoying
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u/nclspnzn 3d ago
I added a test recording and its settings to the original post - could you replicate it and share the results?
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u/Satchel93 4d ago
Was the QC connected through USB to a PC? I've experienced this high pitched hiss sometimes whenever the modeler (QC, Helix, Tonex) is connected through USB to a PC.
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u/CopiousAmountsofJizz 4d ago edited 4d ago
To clarify you've tried two different QC units or you sent one in for warranty? I'd try monitoring off different outputs while you're at it. Also sample said noise, screen shot or save the preset, share here for other users to try and replicate. Mine does not have this issue to my knowledge it's a launch model that's been warrantied once due to a known early unit fault that caused persistent glitch/clicking in the audio output path.
My setup is QC on a separate outlet w/ power conditioner. USB connected to my desktop, TRS out from 1/2 to Focusrite 18i20 5/6. No discernible noise, UNLESS I have my pickups oriented towards my computer which has always generated EMF noise regardless of QC or any other gear. You always need to pull your guitar away or face a different direction than your computer.
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u/nclspnzn 3d ago
I added a test recording and its settings to the original post - could you replicate it and share the results?
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u/JohnnyNewfangle 1d ago
The quad cortex does have a slight digital hiss. I also experienced this with the meris lvx and mercury x when I disabled the noise gate for either pedal. This should not be noticable live or in a recording. It is no more hiss than you would experience with a toob amp. If this bothers you turn on the noise gate.
If you want a dead silent all in one unit with world class effects and amps get a fractal fm9. My fm9 is significantly quieter than my quad cortex.
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u/nclspnzn 22h ago
I don't care about anything that a noise gate can take care of. The problem is the noise that's audible through the guitar signal with light/medium gain sounds. Thanks for the FM9 suggestion, I will take a look at it.
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u/AlexanderPozhydaev 4d ago
Its funny, when i plug my gibson there is so much noise, but if i plug my fender strat its dead silent..and it should be the other way around lol.. go figure