The brilliant and innovative system for stretching audio like play-doh. I quite literally use it on every project. From the amazing sound quality to ease of use, I couldn’t be happier.
But sometimes we all run into a situation with Flex. And then the our first immediate reaction is:
“What the F%!#?! Why isn’t flex working?!”
There are, of course, a million and one different ways you could use Flex Time. And with that many options, I suppose there’s at least one time it’ll screw up.
More often than not though, I hang my head in shame because of one tiny detail I forgot about.
Those tiny details are always the worst, aren’t they?
So today I want to save you some frustration when it comes to Flex Time. This list may not have all the answers, but it should have most.
1. Audio Region Shrinks/Expands When Flex Time is Turned On
This is probably the most asked question I see on forums related to Flex Time.
You need to Flex a track. Maybe you needed to tighten an instrument to the grid. Or perhaps you want to change it in a creative way.
What happens though, is nothing short of bizarre.
You open up Flex Time (Cmd – F), and turn on Flex for your track. Logic analyzes your audio and…
Your audio region suddenly changes length in a big way:
Even worse – your track is playing at a speed no where close to how it should actually sound!
What the heck happened???
First off, don’t panic!
Flex didn’t break your instrument. And this issue is fixable.
What we’re dealing with here is Tempo Information that’s stored inside your audio region.
What the heck is Tempo Information?
Anytime you work with audio in a Logic project, Logic adds tiny bits of information to your audio files.
And one of the things it stores in your audio files is tempo.
This makes it super easy for Logic to import and export audio files between projects.
For example, if you load up a bunch of tracks from one project into another, Logic asks if you’d like to import the tempo as well.
The only time this is a problem is when you’re flexing an imported track in a session with a different tempo.
99.9% of the time this is no biggie. But since the audio region’s tempo doesn’t match the project tempo, a boo boo occurs.
When you turn on flex for that audio region, flex has to try and reconcile the conflicting tempos.
So your region reverts to the length it would be at its internal tempo, but plays at the tempo of the project.
In this case, we need to remove the tempo information from your audio region. And then we’ll need to export the project’s tempo into the audio file.
Start by turning off Flex Time. Then select the region you wish to fix.
Next go up to the Edit menu in the Arrange Window header and go down to Tempo:
- Edit > Tempo > Remove Tempo Information From Audio File
Once you remove the tempo information, you’ll need to replace it with the current project’s tempo:
- Edit > Tempo > Export Tempo Information to Audio File
Now turn on Flex for your audio region. Notice anything?
It stays as stable as a horse.
2. Audio Region isn’t Changing to Flex Mode
Sometimes an audio region doesn’t seem to want to get on the Flex wagon.
You turn on Flex Time with Cmd – F, and one lonely region doesn’t seem to want to cooperate:
This is an easy fix. But it’s gonna sound silly:
Flex isn’t enabled for that one audio region.
I know, but believe me. For one reason or another, that one audio region has flex turned off.
To find out, highlight that region. Then go to the Inspector with Key Command I:
And open the Region Inspector section at the top:
And if you take a look, there’s a header in there called Flex with a box next to it. Click on that box:
Don’t fret my friend. No one will know 🙂
3. Flex Sounds Phasey
You’ve started flexing your tracks. But for some reason, flexing makes your tracks sound phasey.
Which is a problem, because you’re looking to stretch the track. Not start a prog rock band.
Flex is supposed to preserve phase, isn’t it? So what gives?
There’s a couple roads you’ll have to wander down to find the root cause:
1. Are Your Tracks Grouped and Phase Locked?
When flexing a multimic instrument such as a drum set, it’s super important to group your tracks.
For instance, you can’t move only the snare track in a multimic kit. Because if you move the snare and not the overheads, kick, or anything else, you’re destroying the phase relationship of the kit.
So it’s important to group all the drum tracks together, and flex them together.
To do this, you’ll want to open the mixer with key command X. Then select all the tracks that you recorded at the same time:
In this example, all these drum tracks were performed and recorded at the same time.
Then click on the Group field, and select the next available group:
A new Group menu should pop up in the region inspector:
With your new group highlighted, open the Setting tab at the bottom of the menu. From there click on Editing (Selection), and Quantize-Locked (Audio) below that:
Now your tracks are phase locked for Flex!
2. Did you pick the right Flex algorithm for your instrument?
Picking the right Flex mode is crucial for quality results.
And each flex mode is designed for a specific purpose:
- Automatic: what Flex guesses is the best mode for your track
- Monophonic: for instruments that only play one note at a time, such as bass or vocals
- Slicing: for slicing transients without compressing or expanding the transients. Perfect for drum editing
- Rhythmic: for rhythmic instruments such as guitars or keyboards
- Polyphonic: for complicated instruments play more than one note at a time, such as guitars
- Speed (FX): for speeding up and slowing down audio
- Tempophone: for a tape style time stretching effect
3. Are you stretching a high-gain, distorted instrument?
Electric guitars fall into this category.
Flex uses some complicated math to alter the timing of your tracks. When you stretch them, it has to approximate and mimic the behavior of your track for it to sound natural.
The more distortion you add to something, the more harmonics are introduced. Which makes the process more complicated.
If you have several mics on a distorted instrument, they’re catching all sorts of frequencies at different times.
Trying to Flex them even when they’re phase-locked is a feat. As flex does its magic, it can’t do its thing without changing the phase of each track.
But in high distorted situations, it reveals the phase shift.
You’re better off bouncing your multimic distorted instrument down to one track and Flexing that.
Flex Time is fantastic for editing and stretching instruments. If you ever run into problems, it’s best to double check your work:
- Audio region expanding or shrinking when you turn Flex on? Remove the tempo information from your region.
- Audio region not switching to Flex mode? Make sure that flex is actually on for that region.
- Audio sounds phasey when you Flex it?
- Make sure that it’s grouped and phase-locked
- Make sure you’re using the right Flex algorithm
- Make sure any high distortion multitracks are bounced to one track for Flex
JOE SCOTT says
Great info, and right on time!
Thanks Joe! Glad to be of help 🙂
Chris you’re a life saver. I was pulling my hair out trying to figure out problem/solution #1. Love your channel as well. THANK YOU!
Thanks for your very informative article. The issues I’m experiencing don’t seem to fall into any of your examples – or maybe they do. I have recorded a violinist who’s a bit on the mature side of life (76), and who consequently has lost some of her strength, control and facility. I thought I can put her in tune and in time, and possibly even tame her sometimes uncontrolled vibrato and make her sound like she used to. It seems not – though sometimes I can. There’s a large degree of inconsistancy here.
I can’t remember all the hoops I’ve been jumping through in order to achieve this. But……
The section I’m having trouble with is very rubato, and she played pretty well in time with the backing. After making some subtle adjustments to the timing, I turn on flex pitch – all hell breaks lose. All of a sudden the timing is nothing like that which we recorded, or what it was a second prior – flying by at almost double the speed.
Stretching a note that’s a beat or two shorter than desired produces a strange burling/gargling sound, or a strange temporary bump in gain mid-note.
I’m now thinking that I have to chop up the audio and place each phrase or note in the correct position – which of course defeats the whole purpose of flex editing.
Based on what you’re describing, I feel that Tempo Information needs to be updated for your violin track. A clear indication is the fact that the performance is dramatically increasing in speed when you turn Flex Pitch on.
Follow the steps above to remove and import tempo information to your audio file.
Additionally, I always separate my Flex steps. So if you did some Flex Time edits, I would Bounce in Place, and then try Flex Pitch on the new Bounce.
Let me know how it goes!
Thanks for your response – and for your suggestions.
I did as you suggested.
On one take that I had mutilated pretty well, the Remove Tempo Information, followed by, Export tempo information seemed to work about 88% – this was raised to 100% by the final stroke of ; the audio file; .
On another take that had been thoroughly mutilated, the Remove & Export Tempo Information steps were at first largely ineffective; though it seems that in conjunction with Reset Manual Flex Edits & Reset All Flex Edits – the track seems back to where it once was. I say that in conjunction because I’m sure I had tried the last two actions with no effect before commenting on your article.
The bottom line is that your suggestions either did the job, or were a large part of achieving the desired result.
Thanks for your help and your wonderful blog.
I’m so happy to hear that the Remove Tempo Information helped you. Thanks for the follow up 🙂
Greg Boser says
I came across this post because I’m having the “phasey’ problem with drums. But I’m working with stereo drum tracks, not individual instrument tracks. If I’m understanding things properly, phase lock is only for multiple files. Is there a fix for a single stereo file?
I’m assuming you’re using the “Slicing” Flex Time algorithm? And you’re trying to Flex one single stereo file?
Phase-locking is used to lock several tracks together. So when you make a Flex edit to one, it makes the same edit to them all.
If you’re experiencing phasiness, I have 2 suggestions. First, I would download a demo of a phase-aligning plugin like SoundRadix’s AutoAlign. The left and right sides of your stereo track may need to be fixed so they’re more in phase with each other.
My other suggestion is less Flex edits. What’s the fewest amount of Flex edits you can get away with to achieve what you’re after?
Hope that helps!
Thank you for summing up flexing as there are some details one should know to avoid to fail.
I have your above mentioned problem that turning on flex expands (or more often compresses) the region.
I always do the stuff with remove tempo information and save the region tempo to the file and then turn flex on. The only thing is that the region length explodes anyway. (this is not always, very often it works very stable after doing tempo cleaning in the files)
I’ve found a workaround for me to save all regions to new files. After that flexing works. (I often work with 400 tempo changes as a result of beat mapping.)
Ok. After weeks I found the solution for above posted problem.
Before saving tempo to the file I must activate a new set of bar signatures (only 4/4, no 13/8, no other).
If I do that exporting of tempo works well and starting flex doesnt change bounders.
After that I switch to my original bar signature set.
It is worth testing as I think it is a bug.
Thanks for sharing your experience and work-around Gerald! For beat-mapping I could see how bouncing the tracks in place would save the new beatmapped tempo info to the files. Logic is very particular when it comes to tempo and Flex!
Eileen Gogan says
Hi I think my problem is related to Flex, I copied a guitar region to another track so I could edit the bits I wanted into a solo. When I pulled the handles out of the edited region to hear another part on the region, the lead vocal track went crazy. There are no groups, and they are on different sends. I’m coming from Reaper, ProT and Mixbus but Logic is the fussiest editing suite ever! Please help.
If you can email me at [email protected] with some screen shots I can try and help. Thanks!
Hi Chris, thank you for this detailed article. I’m having the issues that are discussed in scenario 1, however when I go to Edit > Tempo, my options are different then the options you show in your screenshot. Do you know how I can get the same options that you have illustrated in your screen shot?
If you give me the ability, I can attach some screenshots so you can see what I mean.
Hey Samuel, feel free to email me: [email protected].
John Ballinger says
Great article! Thanks.
Raymond Richardson says
Hello I’m using Roland SPD SX into my Logic Pro x VIA usb & left & right audio leads into my sound card, some waves show in flex pitch & some don’t , I see the wave but doesn’t flex pitch it please help ray Thankyou
Amber Rhoads says
Did you ever get an answer to this? I’m having the same problem. One note doesn’t have the flex pitch and I need to fix it.
Hi Amber and Ray,
Thanks for your comments! From what I understand you have a note that wasn’t detected by Flex Pitch, but you need to tune that note. Is this correct?
You should be able to use the pencil tool to draw in the correct note for any note that is missing. But in case that doesn’t work for you, here are a couple of ideas:
– Separate the part you need to correct using the Marquee Tool, and bounce in place. Try Flex-enabling the new Audio Region to see if this corrects the problem.
– Is the Audio very quiet? Try boosting the Gain of the separated region or whole region, and then bouncing in place. Enable Flex for the new region to see if this fixes the problems.
I do hope this helps!
chris.vandeviver Very helpful and well written article. Unfortunately it didn’t address the issues I’m having with flextime. While tightening the timing on, especially tuned percussion tracks using polyphonic flex on marimba, vibraphone, bells, cymbles etc the transients turn to mush. Creating a slight but very noticeable swoosh into each note, inconsistently. Strangely it is often worse for notes that need little to no timing fix. And when I delete flex markers for those notes it actually makes it worse! I have searched high and low and tried everything to fix this but it is driving me nuts! Also with slicing mode in drums I find the transient markers align with the big hit but cut off the very beginning of each transient separating them and causing clicks which is solved by going through every single transient and placing it at a zero point before the hit and realigning with the bar manually but I may as well edit the old fashioned way. To me flextime is a miracle turned nightmare lol. Is there anything I am missing to be able to get logic to work with the transients better? Flex pitch on vocals and flextime on bass work great for me but other than that the transients on my other tracks seem to be a problem for flextime. I would love some insights into this if anybody has any.
Chris Coletti says
David Harris says
I’m having a problem not mentioned here. I have used flex pitch to great effect on vocals for weeks, and all of the sudden, it isn’t working. When I’m in the flex pitch editor it works fine. When I exit out of flex pitch editor, it doesn’t save the changes I made. Go back to the editor and the changes are there, leave it, they disappear. I’ve tried bouncing the track and editing it in a new file with no change. Thoughts?
I’m having this same problem.
Flynn Wade says
THANK YOU THANK YOU THANK YOU!
PS: If you’re into proggy rock check out my music @ https://flynnwade.com
The right information at the right time. Thanks a lot
Michael Alan Schoonover says
Your solution #1 worked for me, although my situation is slightly different (I think). I two sections–the first in 4/4, the 2nd in 7/8. If I turn on flex on the 7/8 section, it shrinks to half the size. By removing the tempo info from the 2nd section file, I got it to work as you explained. But this seems very weird to me. Do I need to use the same denominator for all time signatures, or something weird like that, to get flex time to work properly for all sections?