Some time ago I started to get interested in the looping technic, so I was trying different programs and vst’s designed for this activity, unfortunately I could not adapt to any of them, surely because I’m already very used to the workflow that I have in REAPER.

This is why I started creating lots of scripts for automating actions to simulate the operation of a looper within REAPER. After a while I realized that the method worked quite well, so in the last year, I’ve given myself the task of unifying all these scripts, simplifying them to the fundamental tasks required to looping.

The result was what I now call Nabla Looper, a set of tools that offer us two modes of use, the Manual Mode, which resembles the operation of the looping pedals (like boss-RC-505, Aeros Loop Studio, etc) and the Arranged Mode (ALK2, Ableton Live).

My main goal is to provide a simple and intuitive system that feels integrated within REAPER, so that, if you take your first steps in this DAW, it’ll not be so difficult for you to start playing with these tools, and if you already have experience in the system, surely you will see the potential it offers to develop your own workflows.

It’s important to clarify that Nabla Looper is simply a set of hundreds of automations that execute native REAPER functions, managed and controlled with the LUA scripting language and the ReaScript API.

Eventually I will be sharing videos on my YouTube channel showing how I use these scripts and how I do and configure my projects, I will also share more useful tools on this website.

Esteban Morales


Esteban – a few months ago I downloaded your looper and fell in love with its simplicity. I’ve been away from it for a while but have started creating a song around a guitar part that I’d like to loop. When I first downloaded – I was having skip issues right AFTER the loop was recorded and it started to play back (literally within the first few seconds. You suggested a fix and it worked… too bad my memory didn’t I’ve set my buffer very very low so I don’t think that is the problem. Do you have any other suggestions. Email me if you have a minute to discuss the issue. I appreciate the work you are doing.


Hi Esteban,
Your Nabla Looper is brilliant! Not only are you a wonderful musician but also a Looper scientist!!
I’ve just downloaded your videos. Your Installation and Basic Usage video is much appreciated and very clear.
I have not tried Looper yet but soon 🙂

Thank you…John

Esteban – what a great update – thanks for fixing the disarm all tracks feature!!! I am looking forward with takes feature – they weren’t covered in the introduction video. I submitted my formal gratitude via Paypal.


Hi Esteban,
thanks a lot for developing the Nabla Looper. I´m coming from ALK2 – it doesn´t exist anymore so as a professional musician I need an alternative software that fit to my needs of live looping.
The installing process worked without any problems and everything looks great.
But it doesn´t work (I´d like to do a project with the arrange mode), I always get an error message:

Nabla Looper Arranged items (Toggle Record) lua 60: bad argument#1 to “GetSetMediaItemTakeInfo_Value” (MediaItem_Take expected)
Same come with lua 84: Info_String”

Any help aprecciated.

Thanks a lot for your time!


Hi Bernd, I have been uploading updates constantly, the current version is 0.2.11, please update and let me know if it works.

Access: Extensions | ReaPack | Synchronize packages, via Reaper’s menu to ensure Nabla Looper is updated to the latest version, or Extensions | ReaPack | Browse package, search for “Nabla” and reinstall. Let me know if it works.

Hi Esteban,
Thank you so much for your work on creating Nabla Looper. This is really something that was sorely missed. I was just thinking of transferring a concert setup to Reaper. I experimented today, I kind of got it. It seems that this should be a stable and convenient solution. I just got a problem in Arranged mode. The nabla ReaDelay plugin is not automatically removed from the FX chain when I stop Reaper. When I run Arranged mode again, another plugin appears. There must be some other trigger?

Thank you!

Hi Feodor,
The issue is fixed now, please update Nabla, current version (0.2.14)

1. Close any projects that have used Nabla before attempting to update.
2. Access: Extensions | ReaPack | Synchronize packages

Let me know if it works!

Esteban, great job on this script. I have installed it through ReaPack and am having some challenges getting Manual mode setup correctly. Do you have instructions for how to setup and run manual mode anywhere? I can only find material for arranged view.



Hi, William, i’m working on the user guide for “Manual Mode”, give me a few more days to finish it and I’ll be posting it on this page.
If you have installed the latest version there are two scripts in the action list:
“Script: Nabla Looper Manual Take (Start_Stop Recording).lua”
“Script: Nabla Looper Manual Take (Discard_Delete).lua”
Only assign shortcuts for those actions in the action list.
For use it just run “Manual Mode” (“Script: Nabla Looper Manual Mode.lua”)
Select a track and hit the shortcut for for “Script: Nabla Looper Manual Take (Start_Stop Recording).lua”, hit again for end a loop and start the playback.

Any action that you send (Start/Stop) will execute at the start of next bar.

Hello, I just tried to install this but getting errors when when installing it.

“C:\Users\Steev\AppData\Roaming\REAPER\Scripts\Nabla Tools\Nabla Looper\Arranged Mode\Nabla Looper Arranged Items (Toggle Monitor).dat: size_t size mismatch in precompiled chunk”

When I try to run the script I get the following error…

“C:\Users\MyAccount\AppData\Roaming\REAPER\Scripts\Nabla Tools\Nabla Looper\Manual Mode\Nabla Looper Manual Mode.dat: size_t size mismatch in precompiled chunk”

This is happening for every script I try to run.

I have uninstalled and reinstalled it several times and deleted the scripts but keep getting these errors.

Any help would be appreciated.


Hi, Steeve,
You need to install only the appropriate version for your reaper base (x32 or x64).
If you have Reaper x64 then try this:
1. Install and then Uninstall: “Nabla Looper Arranged Mode x32.lua”
2. Install only “Nabla Looper Arranged Mode x64.lua”

If you are using x32, then just install “Nabla Looper Arranged Mode x32.lua”

Please let me know if this work for you or if you need any further information. Cheers


Thank you. I was trying to uninstall the x32 but it didn’t seem to want to before.

Thanks for you help.

Hi Esteban,
I’m trying to install SWS-v2.10.01 in Windows 7 32bit portable. When I follow the SWS manual’s description to “follow the prompts to install the SWS Extensions automatically into your \REAPER\Plugins folder”, the OK button on the installer is not armed and ready to go.

The only place in the install path where the OK button becomes active is this: \Reaper 6.13 Portable\App\32

Have SWS made a mistake? I welcome and thank you for your advice 🙂


Hi Esteban,
I may have solved the SWS install problem. I installed SWS into a functioning folder, then cut and pasted into REAPERxxPortable\App\Reaper\UserPlugins. It shows up in Reaper Extensions.
Sorry if I caused you time and trouble with SWS. It’s really nothing to do with Nabla.Tools.
Have not gone farther with this. I’ll now watch your install instructions and video again.


Hello Esteban,
Following your excellent video: Nabla Looper v2 for REAPER DAW | Installation Tutorial, do you plan to publish a follow up to that? No hurry. Take care of your self with Covid floating around.

Hi, John,
I’m planning to make more videos, I have not had enough time to make them, but for now, I’m making code improvements and working on some essentials features that are missing in Nabla.
If you have any question don’t hesitate to email me at

Hi Esteban!!

First of all, I want to thank your for this amazing tool. I’m sure a lot of work went into it, and I must say this could be a gamechanger for a lot of people. Your willingness to share it with the community and also offer some support is really not to be taken granted, and I appreciate a lot.

I also wanted to report an issue, maybe you know what’s causing it.
I’m working on a Windows 10 64 bit machine, and I’m using a Zoom H4n as an audio inteface.
I get some artifacting each time I start to record and on the first loop reproduction after record.
To be more specific, I hear some clicking, like the track wasn’t snapped at zero crossing, I tried adding a fade in but it seems not to work. The issue however is present only when the recording item starts and at the first playback item, not on the successive playback items.

First I had the issue of audio skipping (going silent for about half a second to be precise), and I was able to solve it by setting the media buffer size and render ahead settings in Reaper (200ms and 50ms for the buffer sizes, 50ms for the render ahead if anyone is wondering, go to Reaper preferences->Buffering) like you suggested in a Youtube comment (I think you can consider adding it to the manual as it could be a common issue), but I still get that click, each time I record a new loop and play it afterwards.

I would love to use Nabla Looper to perform live but first I need to fix this or it won’t really be usable. All the rest works amazing!
If you have encountered this problem before or you know what may be causing it, it would help immensely!

All the best and thanks again for your work and will to share,


Hi, Martino,
Thanks for your feedback, to avoid audio glitches at the start of a loop recording you can increase the “Pre-recording time” in nabla settings, this way you give enough time to fully load any VST’s in the track before the recording item starts.
For the artifacts at the end of a loop recording the best way is to enable the “Safe Mode” option within nabla settings and increase the “Buffer time” if you hear audio gaps, also you can try with the “Preserve PDC” option disabled.

Unfortunately these small audio glitches in the first playback item are difficult to avoid due to the functions that nabla has to perform just when a recording item ends, but with some configurations we can get them to become almost imperceptible.

It helps a lot to use long “Monitor Items” instead of monitoring each “Record Item”, for example, I have a guitar input and I want to record four loops, what I do is create a track folder, in the parent folder I put my fx’s, inside this folder I create a track to monitor my guitar and draw a Monitor Item the length of the four loops, then I add another four tracks in which I will put my Record/Playback items, now I have two options, create mute automation in the sections of the record loops or use “Script: Nabla Looper Arranged Items (Toggle Record Mute).lua”.
This way, I avoid hearing the clicks that are generated when a track is armed/disarmed and it’s the way that has worked best for me.

I hope that is clear, I also attached a reaper project with a simple Audio/MIDI arrangement. Go ahead to: Extension > Notes and select a track to show some track annotations (select: “Track Notes” in the notes window).