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Bug-Glitch in LogicPro: how to deal with weird behavior

Sir Hannes
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Hey folks,

I am dealing since weeks with an audio glitch I've got between 2 bars. And it is in the final mix down. Imagine a filter opening way too fast and rushing through Hz -> kHz within 1/4 of a second: zuuuuip! Do you have ideas or had a similar experience and how did you deal with it?

- it's in the middle of a 170 track arrangement, that makes it hard to find the error easily.

- all those tracks who play at these 2 bars I re-listened many times, in cycle, in a wider cycle, in solo/ with all.

- I checked every track and busses for any (weird) automation, e.g. if copy and paste with automation and you get these brickwall-jumps between two points, even those who are on tracks without midi-region, audio-objects, anything else or muted.

- I extended any EQ or Filter automation up to 1 bar to make every ramp smooth like butter.

- I narrowed it down to DMD (at least I thought). I narrowed it down to a HiHat closed because finally I discovered the spike visually in the equalizer (success!!).

- "HiHat closed" uses: original main DMD, Graphic EQ (this one does create bugs in the past in other projects so I kicked it out, but here this is just a static eq, no movement at all), Overdrive, PEQ 3000 (MIDAS Eq where I can see the spike visually), SPL Transient (Attack only at 3, nothing like a "spike" setting). No Volume automation nor send.

- there's nothing going on in this track automation wise, nor in the DMD main track.

- there's no bus processing nor has it automation.

I spent an hour listening in cycle. The weird thing is that it is not everytime there and I can't figure out the behavior behind it. If I would be a programmer, I couldn't sleep at night. It's so unlogical. But it's there in my mixdowns. What do you have ideas to deal with it within such a big arrangement? What information could help you to think out of the box?

Is it possible, that any automation in the background is going on I can't see? In an older threat I reported that a track volume always jumps back to -12dB although no automation-lane, nor region-automation nor anything else is there. David figured out, that there was garbage automation I couldn't see.

Edited by Sir Hannes
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yes, I checked automation within the region and for the track: there's no. I checked also for other CC going on.

I see the volume clip in the internal visualizer of the EQ plugin. And yes, the HighCut (24dB slope) is automated. But very gentle over time.

I am already thinking, the t.c. electronics MIDAS PEQ could have a lousy code or connection within Logic. Also I find it at different places of my song only: if I jump to bars and press spacebar. 

Edited by Sir Hannes
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  • 4 weeks later...
  • Solution

So here's the solution:

The Bug-Track is DMD -> Q-Sampler Track with a HiHat-Sample from Logic loaded in and the PlugIn Graphic EQ (internal).

No automation nor region automation.

Muted this track as it's buggy. Done.

I lost hours over a month looking for this. When sending demos to other producers, I always had to include the information "unknown glitch at bar 34" so they wouldn't feel compelled to write me back that they found "this problem".


Happy producing out there! 🙂 



(It might be the Graphic EQ causes severe glitches and other problems in my environment already in the past. For example, no audio goes through until I bypass the graphic EQ. One Workaround: Pressing the internal In button (the one on the left) will free this plugin from it's weird behavior.)



Edited by Sir Hannes
Graphic EQ
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