# Quad Cortex output and input peaking with nothing connected **URL:** \ **Category:** Quad Cortex\ **Tags:** support\ **Created:** [October 11, 2025, 4:10pm UTC](https://unity.neuraldsp.com/t/quad-cortex-output-and-input-peaking-with-nothing-connected/19816 "2025-10-11T16:10:09Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![acordito](https://avatars.discourse-cdn.com/v4/letter/a/2acd7d/32.png) [@acordito](https://unity.neuraldsp.com/u/acordito)\ **Post date:** [October 11, 2025, 4:10pm UTC](https://unity.neuraldsp.com/t/quad-cortex-output-and-input-peaking-with-nothing-connected/19816/1 "2025-10-11T16:10:09Z")
Hi!! Im writing just to know if anyone has the same problem I’ve got with the Quad Cortex. One day the unit started to make like a popcorn noise… I turned off/on .. the noise gone. Couple of days after again.. but the noise persists like hard pink noise… I read in a forum someone used a contact cleaner Spray… I did the same and the problem was solved. Sometimes appears again, Spray and gone… until a main rehearsal/Soundchek in a theater just before the show with Tv Recording included… the noise was terrible… I had to find pedals somewhere and connect direct to the PA with an amp emulation from the sound console. I bought a new official power supply… and now the problem persists. I don’t have anything connected to the QC and the out and inputs levels are almost peaking… now even with no sound. Yes… I restarted, Factory configuration, press A+H loading screen, etc… the same.. I contacted to neural support and after severals mails and photo/videos.. they sent me to Thomann where I bought the QC… My warranty expired 3 months ago so they asked me to send the QC to Germany ( Im in Canary Islands - Spain ) I have to pay the delivery there and return just to offer me a budget. If it is too expensive or I don’t want to repair it I have to pay an extra 50 euros for the Budget… Anyone has the same problem with the QC? If so, could it be solved? Anyone knows Spanish service support/technician? Thanks in advance !!! ---
**Author:** ![SelfTitledLP](https://avatars.discourse-cdn.com/v4/letter/s/ecc23a/32.png) [@SelfTitledLP](https://unity.neuraldsp.com/u/SelfTitledLP)\ **Post date:** [October 11, 2025, 5:35pm UTC](https://unity.neuraldsp.com/t/quad-cortex-output-and-input-peaking-with-nothing-connected/19816/2 "2025-10-11T17:35:29Z")
You’ll need to send it to Thomann for repair. That’s definitely a hardware problem and not an easy fix with contact cleaner, etc. I wouldn’t recommend having a random shop fix it. Just send it to Thomann since they’ll be the only ones with the proper parts aside from Neural. Realistically to repair it, I would be prepared for it to be a few hundred dollars, but cannot say for sure. Just going off the cost I’ve seen from other people, and the QC being a a very specific digital device. ---
**Author:** ![aoloso](https://avatars.discourse-cdn.com/v4/letter/a/dec6dc/32.png) [@aoloso](https://unity.neuraldsp.com/u/aoloso)\ **Post date:** [October 13, 2025, 8:23am UTC](https://unity.neuraldsp.com/t/quad-cortex-output-and-input-peaking-with-nothing-connected/19816/3 "2025-10-13T08:23:16Z")
Several had this problem. Me too - i’ve sent my unit to thomann and they replaced the I/O board. I always had this issue when playing live (preparing for soundcheck). Last saturday we played a show again and it’s the first time i haven’t had this issue, FINALLY! So good luck with your unit, thomann will fix it pretty fast. ---
**Author:** ![RJMiddel](https://sea2.discourse-cdn.com/flex020/user_avatar/unity.neuraldsp.com/rjmiddel/32/2267_2.png) [@RJMiddel](https://unity.neuraldsp.com/u/RJMiddel)\ **Post date:** [October 15, 2025, 5:42pm UTC](https://unity.neuraldsp.com/t/quad-cortex-output-and-input-peaking-with-nothing-connected/19816/4 "2025-10-15T17:42:23Z")
I have exactly the same issue. FIrst I thought I fixed it by using contact dpray and shared that solution on Facebook group as well, but today just before my gig started, I faced the same issue again so I couldnt use it today. I am in contact with Neural DSP at this moment and probably I need to sent ti to them to get it fixed. My warranty is alreayd over because I bought the unit in May 2021, but I think Neural should think about to at least share the costs because I read that a lot of consumers have the same issue. Probably there is a weak component in the unit… We wil lsee. I will update you once I know more ---
**Author:** ![acordito](https://avatars.discourse-cdn.com/v4/letter/a/2acd7d/32.png) [@acordito](https://unity.neuraldsp.com/u/acordito)\ **Post date:** [October 16, 2025, 2:09pm UTC](https://unity.neuraldsp.com/t/quad-cortex-output-and-input-peaking-with-nothing-connected/19816/5 "2025-10-16T14:09:43Z")
HI!!! Exactly!!! I Contacted them and Thomann… I have no warranty and I have to pay the delivery service plus the reparation work. I´m arranging directly with Neural to make it happen.. Apparently as you said, this is a topic issue which to be honest, if many users have… the should repair for free anytime. This is not a bad use, strike or something like that… but anyways… I need the QC for work and I’ll repair it…. once y have news I let you know as well!!! ( Two days now without noise… but Im not going to risk a show using it, I’ll send it to neural 😉 ) ---
**Author:** ![RJMiddel](https://sea2.discourse-cdn.com/flex020/user_avatar/unity.neuraldsp.com/rjmiddel/32/2267_2.png) [@RJMiddel](https://unity.neuraldsp.com/u/RJMiddel)\ **Post date:** [October 16, 2025, 2:37pm UTC](https://unity.neuraldsp.com/t/quad-cortex-output-and-input-peaking-with-nothing-connected/19816/6 "2025-10-16T14:37:33Z")
Unfortunate Neural will not pay the repaircosts. They cahege me for 435 euro exl vat. I will let it foxed but i will never buy a neural product amymore. I have never heard the line6 had hardware issues. I am veru disappointed in Neural. ---
**Author:** ![aoloso](https://avatars.discourse-cdn.com/v4/letter/a/dec6dc/32.png) [@aoloso](https://unity.neuraldsp.com/u/aoloso)\ **Post date:** [October 17, 2025, 7:26am UTC](https://unity.neuraldsp.com/t/quad-cortex-output-and-input-peaking-with-nothing-connected/19816/7 "2025-10-17T07:26:25Z")
I’m not deep into the Line6 Forums and don’t know about their hardware. I don’t want to defend Neural - but it’s a piece of hardware and the probability for any issues is real on any device. But i can understand your frustration for sure. Where have you brought the QC? Maybe you can figure something out with your reseller?