INPUT Level Bug (randomly louder) sorta fixed! - been waiting a long time to talk about this - Anyone else?

Wanted to do my due diligence and testing first, sorry for the novel.

Here’s the main issue: The QC will randomly be so much louder on the input level (about 13db hotter).

My experience:
I’ve owned this unit for 1 year and it’s happened about 5-10 times now after powering up. I use my QC very often, nearly 5 days a week either in studio, on tour, or rehearsal—point being it get’s powered on and off ALOT. I’d say the rate at which it does this ‘randomly hotter input signal’ is in the 1% range, but man is it frustrating because rebooting or any sort of power cycling doesn’t seem to consistently fix it right away. I just either move on and reduce the input gain on the I/O Settings page or turn it off for about an hour and then it seems to go back to normal. Pretty weird.

The first time it happened I thought I was going crazy, and naturally went down the line of testing every variable from guitars, cables, power…you name it, I tried it. Nothing was the clear issue, so all I had were my ears telling me that it sounds like the pickups on all my guitars got so much hotter overnight. Then I did a tour last autumn with a band that had 5 QC’s out with them. As we both had QC’s I’d often geek out with their guitar techs. One day one of them asked if I ever encountered an issue where the input level randomly seemed way hotter. Man did I feel validated! It happened to them twice in a 30-day run, and nothing seemed to fix it until it just seemed to not happen the next day in another venue. One would suspect power issues/differences venue-to-venue, but that’s where the next part comes in.

The testing:
I’ve been in a studio for the last two months working on a record. We’ve got recalls, presets, wiring, routing all dialed in and nothing has changed or moved since. The kind of consistency that was PERFECT for when the QC acted up again this afternoon.

So, I’ve been printing a DI through the QC while also taking the ‘amp’ signal obviously. Today I power up, plug in, start noodling and immediately can tell the pickups sound HOT. I recalled the EXACT settings from last night’s session in my DAW, interface, QC, guitar. We re-track a guitar part to compare to yesterdays work. BOOM. The DI is coming in 13db louder and the waveform looks incredibly different. It has to be happening at the input point on the QC because even the ‘amp’ sounds way hotter…and to my surprise, after comparing the two DI tracks it’s also changed the TONE. There’s way more midrange now.

I took the opportunity of how consistent my setup is to try and find the culprit. I’ve already gone a bit crazy before with this so why not get even more exhaustive? During every change or swap (be it a cable, a power supply, a power outlet, even the interface), I would try both a hot swap while the QC was on and a swap while the QC was off. You probably think I’m crazy but let me tell you that the ONLY thing that actually worked and made the input level return to normal was unplugging the instrument cable from Input 1 while the QC was ON, removing the power cable, THEN plugging in the instrument cable again while it was still OFF, THEN plugging in the power cable which automatically powers it up.

I’d like the last hour and a half of my life back.

To complete the test I record another DI. We’re back baby! And 100% the tone is back to normal which doubly confirms that not only has this issues been making the input hotter, it’s been changing the tone. Sheesh.

So while I may know how to fix this, it still doesn’t answer why this happens randomly from time to time, especially under the current conditions (the QC has been plugged in with the same cables and routing, nothing being changed for over a month). And yes I’m running the latest CorOS 1.4.0. Either way this issue has been happening before and after I updated.

Anyone else?


@dannyrico - Please send an email to so they can troubleshoot, that way they can either resolve or escalate your issues if needed. Thanks!

Very interesting investigation. Thanks for sharing :+1:
Based on the described behavior it seems unlikely to be a hardware fault but rather something software related. I hope your findings and extensive testing will help to troubleshoot the issue on NDSP side.

Wow, crazy, let’s hope that Neural can get to the bottom of it & fix this issue promptly for you. I’ve not experienced anything like this (thankfully) but my unit hasn’t been getting much in the way of heavy use as of yet though.

I have never experienced this. QC has been rock solid for me. Let’s see what NDSP support comes up with.

What you describe (changes in level and tone) could be related to input impedance. I wonder if that’s somehow related to your issue.

Another possibility is the inputs are TRS. So if somehow the ring was intermittently grounded, that might result in level changes.

I too have a ritual I must go through with my QC
I use it nearly every day
When I first turn it on in the morning I get a huge static noise and the input 1 light lights up and flashes. Usually it last for 45 seconds and then is ok. This happens even when I unplug inputs 1&2. Later on in the day when I turn it on again this does not happen
Another problem is the input 2 ( my microphone Chanel ) is considerably down until I momentarily raise it right up and then return it to my usual setting So my mic (and also GTR levels -input 1) are down on volume until I do this trick to get back to normal
Next time I turn it on that day I don’t have to do this
I’m worried that one day this fix won’t work!!!
These things didn’t happen with earlier firmwares. It’s only been after the last couple of updates.
Still a great machine and the heart of my system
Cheers BlaMM

@BlaMM - Please email with your issue and a video so they can troubleshoot and escalate if necessary.

If anyone runs into this problem please email into support as well thank you.