Output overload (turns red) resulting in distorted output

Hi All. Sorry if this has been covered elsewhere, but despite having very clean sounds (profiles) at home and at rehearsal, I did my first gig with the QC last night, and it was absolutely dreadful - constantly a very nasty distortion. I rather foolishly didn’t have my Kemper to back myself up so had to tolerate it all night :frowning:

Can anyone think of a reason for this? Same guitar - same QC volume output level. The output signal overload was almost constantly on.

Would appreciate any recommendations. As I said, I never have this problem at home or rehearsal room so I am clueless as to what might be causing the ‘overload’. I haven’t changed the output volume (profiles are all set at 0dB [no boost]). Note that I do not have a gate selected. Not sure if this should make any difference.


This same problem occurred to me. I play bass semi regularly at a venue seating <1k people. They use line arrays/subs and the sound is top notch. Its a silent stage, so we run in-ears (& p16’s) and feed line outs from xlr or 1/4”.

I transitioned from bass straight to the house to cortex to FOH. Initially I had to reduce the volume to compensate for the hot levels being used (which sacrificed tone integrity). It took a dedicated sound check to work out the bug. A combination of plugins/gain staging was the issue. The sound guy zero’d out my channel and started from scratch. What a difference.

IMO gain staging seems to be the make/break issue for users of the cortex. Leaving the attenuator (volume) knob 100% while adjusting gain can be tricky, never mind impedance and your input leveling to boot.

I use presets as songs, dialing in the tone that’s appropriate. Completion is AFTER final target db is achieved which is in a range of 3 db. My goal is to be as consistent as possible and let the sound people do their thing. My advice is a sound check. It can be done. The cortex has massive tone shaping potential. Keep at it.

Thanks Christopher! I appreciate the input. I did think about gain staging, and in fairness, the band before us gave us 5 minutes to get on stage, so no chance of a sound check! However, I did double check the gain on the PA (I was operating from stage – sadly no such luck when it comes to house set-ups!) I try to aim for around -18dB, peaking at -12dB (I find I have to boost solos to +6dB or even more).

The other thing of course is the clipping seems to be within the QC, as it is the output that was causing the clip (to be almost constantly in the red). I’m assuming that was what was causing the distortion. This was the same for quite a few profiles (I typically work in scenes, using one preset per set of scenes)

The other anomaly of course, is that it is fine in other circumstances, though playing through an FRFR in those cases.

But I agree… I need to reset, and do some delving!

Thank you.

| Mick Matthews

How did the QC act once you got back home, back to normal? Were you listening through monitor(s) or FRFR(s)? Was the signal distorted through the PA mains, as well. This may be a silly question but, could it be that you were simply picking harder at the gig than you do at home.

Not a stupid question at all, Pete. But no – I am usually quite consistent with my picking level.

I’ve not had a chance to test it out at home. The ONLY difference between ‘home’ and ‘live’ was that at home, I am around 40% volume. Live was around 55% (I know! Some say run it at 100%!!).

I usually play through FRFR (Headrush at home. Mission engineering at rehearsal studio). For the gig, it was directly into the FOH and monitors. I had the same clipping / distortion through both. I’m going to set it up through my mixer today, and see if I can emulate / control it.

Thanks! Mick.

| Mick Matthews

Which outputs is you main volume controlling? Is it possible you were sending 100% to FOH rather than the 55% you mentioned? That is actually a good strategy generally, with the main volume knob only controlling your monitor. But not if your presets are not gain staged properly.

Sounds like your input level somehow got set too high or the volume on your guitar was set higher than usual or perhaps a bad guitar cable. Another possibility is something leveled improperly in your FX loop if you were using one. Something had to be introducing higher than normal levels into your signal chain in the QC, if the outputs were in the red that night and aren’t ordinarily.

Well. Maybe you are onto something? I have the QC sending to outputs 1&2, through an I/O module on a pedalboard. From that module, I was only going mono to the PA – so output 1.

But again, you may have a point? I only checked the input level… not the output level. About to go. And do that, I guess!

… However, that wouldn’t explain why the QC is clipping, before the PA? Would it?

| Mick Matthews

I’d recommend going to the connections page and highlighting each set of outputs to check their meters. I usually try to set the outputs with 4-6db of headroom on my hottest preset/scene. If the meters look good but you’re still getting a red output block, that would indicate an internal gain-staging issue.

I will do. Great advice! Thanks

Actually good point, need to check your output levels as well as your input.

Well. I tried emulating everything today. I checked output levels on both Row 1 (2) and Row 3(4) if appropriate. All looked good.

My mixer (Presonus Studio Live S3) was also good. Gain was set so the input was around -18dB (sans solo boost).

I then checked my Shure wireless system (forgot to mention that). I dropped the gain on that but didn’t make any difference. I even changed the cable to the transmitter (I’ve had issues with those Shure cables before). Still didn’t fix anything.

However, I think the culprit MIGHT be a compressor (Wampler) I had before the amp in each scene. I took the compressor completely out and it seems to have fixed the issue. I’m not sure why I never had clipping in other environments (home and rehearsal) through FRFR but it has to be related.

Anyway. Until the next time it happens!! (hopefully, never!).

Thanks to everyone for your input and suggestions, and help! I really appreciate it.

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