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).
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.
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.