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2XB303 Acid Bass Loop Maker

by Rob Wilmot

iPhone · iPad

Active Last checked 31 Jul 2026

Quick verdict

What it is
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At a glance
  • $1.99

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Key functions

Function Availability Access Scope Evidence
Family Sharing Yes Unknown App Store Store published

Screens

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Pricing & paywalls

App Store

  • Price: $1.99

Ratings & reviews

App Store

4.7 57 ratings · App Store

  1. 4/5Fun and useful, just one problem…

    I don’t know if anyone else has experienced this with this app but the metronome does not sync up to the sequencer at all, it doesn’t even play at the same tempo. Otherwise though, I’ve definitely enjoyed it. I just wish I could use the metronome with it

    phillybobthorton · 31 Jul 2026

  2. 4/5Still trying to figure it out

    It’s been fun using the presets and random sequences. I really dig this ap.

    L41rD · 31 Jul 2026

  3. 5/5Really Nice 303

    One of the best Roland 303 bass line synths I have heard on iOS. I like it better than Troublemaker and Bass Line. In its current state it is as authentic sounding as Syntronik’s 303 emulation, Rebirth 338 and Retronyms’ TT-303. It would be a go to app with AUv3 in my opinion. Works fine in AUM using IAA and syncs to tempo thanks to Abelton Link. Has decent effects (echo, distortion, and compression/ducking) that provide an old school vibe and a musically useful signal boost. Filter section is nice and it has midi capability. You can also capture the audio and send to AudioShare. Sequencer is easy to use. The generate sequence feature is good and allows the user to pick the notes used. GUI is functional but further development for the entire app is welcomed. For the price, it is a no brainer to down load if you are a fan of this kind of sound. Honestly, you would have to purchase hardware in order to do better. Kudos to the developer.

    Guycoolio · 31 Jul 2026

  4. 5/52XB303 4 Acid Victory

    One may ask: do we really need another iOS 303 emulator? The answer (if you love 303s) is Yes and 2XB303 earns its place within the existing arena by offering some unique takes on the theme and sounding Great. I learned the (also awesome) 6X806 app first so it was easier to understand the workflow here and the recently improved knob control makes tweaking all the more fun. It’s also capable of less 303-ish sounds and (perhaps most importantly) I keep making new stuff with it. Yes!

    NoUserErrorHere! · 31 Jul 2026

  5. 5/5Bluetooth enabled? Yesssss!

    Enjoying the the app very much. I do to want use it with Bluetooth speakers but can’t connect. Please advise me to enable this function. Keep up the good work. Yay! Bluetooth working fine. Thanks and a star added today!

    Zztoupe · 31 Jul 2026

Privacy & accessibility

App Store

Privacy

  • Data Not Collected Developer declared

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Versions

App Store

  • 1.0
  • 1.1

    Added support for Audioshare. Now you can easily export to Audioshare with one button for easy sharing of your audio recordings between apps and tools like trim/normalize Fixed some bugs and made some other minor changes.

  • 1.2

    Improved contrast. Previously it was a bit "dull", especially in daylight. Made knobs a bit more "knobby" and less "jumpy" Added a knob helper for fine adjustments. Tap the knob and swipe up and down the screen for finer adjustment of the current knob.

  • 1.3

    Added Midi Note out. Now Channels 1 and 2 send MIDI note data to respective channels.

  • 1.4

    New Live Control feature: In [Sequence/Control/Pattern], instantly switch to a saved sequence while playing. Keys correspond to stored program numbers, starting from the current program thats loaded (key 1 is your current program, key 2 is current program+1). Highlighted keys show stored programs. This is great for building up live tracks, or instant crossfading between programs. You can also "Hold settings" so it locks settings like effects. Added the ability to save while recording & choose destination to save to. To save you press "Save all", it then flashes. Now choose destination ("!" means its occupied ) then press "Save All" to confirm.

  • 1.5

    Fixed an audio bug on iPhone X

  • 1.6

    1: Changed the way the dials work: Instead of jumping instantly to where you touch, you can now smoothly turn the dials by moving up and down the screen after the initial touch on the dial you want to adjust. Also, if you double click the dial, it will snap to either of three nearest points (start, mid-point and end) which is handy for resetting to default positions. If you preferred the original touch to point method, you can choose that way in the settings/system. 2: Moved WAVE shape dial to quick access buttons. 3. Fixed an issue where clicking to open the Ableton Link settings view for the first time would interrupt the main audio processing thread.

  • 1.7

    Some optimisation.

  • 1.8

    Some efficiency changes in code. Removed the input channel for use as Audiobus filter (This broke on many devices anyway and was unreliable)

  • 1.9

    Fixed the swing/shuffle effect: This never quite worked well as it sometimes cancelled out some glide notes. Finally, this has now be rewritten so it just works. Now you can get those groovy shuffle swing patterns. Swing amount is a global setting found in the main sequencer/sequence menu. This also affects the backing beats.

  • 2.0

    A consolidated list of app updates all rolled into one taken from the sister app 6X806 Noise Drum Synth: BPM increments now give increments of 1 for single tap or 5 with a double tap. Captured audio loops exported to Audioshare and Email now adds BPM and date/time to file name. Better dial control: Now you should be able to swipe up and down the knob levels quicker while maintaining refine control. It also snaps to min/max levels instead of wobbling. INIT button for quickly clearing the currently loaded pattern to start a fresh program. Found in System/Settings. Minor update to the UI to bring style up to date with 6X806.

  • 2.1

    This update looks to fix a possible conflict in the Audiobus and Inter-App-Audio nodes. This could cause the nodes from not showing up or behaving properly in some apps. Last update: A consolidated list of app updates all rolled into one taken from the sister app 6X806 Noise Drum Synth: BPM increments now give increments of 1 for single tap or 5 with a double tap. Captured audio loops exported to Audioshare and Email now adds BPM and date/time to file name. Better dial control: Now you should be able to swipe up and down the knob levels quicker while maintaining refine control. It also snaps to min/max levels instead of wobbling. INIT button for quickly clearing the currently loaded pattern to start a fresh program. Found in System/Settings. Minor update to the UI to bring style up to date with 6X806.

  • 2.2

    Added support for Bluetooth headphones and speakers. Previous updates: Too fix a possible conflict in the Audiobus and Inter-App-Audio nodes. This could cause the nodes from not showing up or behaving properly in some apps. Last update: A consolidated list of app updates all rolled into one taken from the sister app 6X806 Noise Drum Synth: BPM increments now give increments of 1 for single tap or 5 with a double tap. Captured audio loops exported to Audioshare and Email now adds BPM and date/time to file name. Better dial control: Now you should be able to swipe up and down the knob levels quicker while maintaining refine control. It also snaps to min/max levels instead of wobbling. INIT button for quickly clearing the currently loaded pattern to start a fresh program. Found in System/Settings. Minor update to the UI to bring style up to date with 6X806.

  • 3

    It has been a while since this was updated so I hope you enjoy some of these updates and added features. Updated Audiobus Updated Ableton Link (includes remote start/stop) Fixed audio level on channel 2 being louder Balanced audio for drum sounds on metronome drum backing Fixed Note On and Note Off from MIDI so this should hold note with a glide Added Midi control of transpose using chosen channel. (Found in Settings/Midi) Added Sequence Trigger from transposing with 2XB303 or MIDI (Found in Sequence/Control) Added a new AutoPad sound layer that uses first note it finds in Channel 1 sequence to play a selected pad sound as backing track. (Found in Sequence/Control, On//Off and Sound 1-22). You can adjust volume in Mixer section. This can give some great results used with transpose in Control section. Increase screen space for MIDI ports Allowed editing of step while running. Just use counter -/+ buttons, in Edit mode and it freezes selected step to where you move to. Resumes following sequence by pressing Edit Menu again. Add Info links etc like other apps - email link and video demo link Auto initialise empty memory slot as it was confusing before keeping the older program loaded.

  • 3.2

    Fixed a bug where pitch wasn’t playing on step edit while it wasn’t running. Changed program loading so if it sees an empty slot, it doesn’t do anything. It will keep the current program. Before it crashed the memory loading silently even though it didn’t ruin the saves.

  • 4

    Added saving of auto pad sounds settings to each pattern. Updated core code improved loop better interruption crash other crashes and UI fixes

  • 4.1

    Improved UI fo iPhone mainly (easier to read)

  • 4.2 · 9 Jun 2025

    Fixed a bug introduced in last version that messed up the loop recording on some phones that also messed up the UI connections. (Sorry bout that!) Also, as this app was released before Apple's IOS files app was introduced, it used an old system of iTunes file sharing. That has now been removed and instead your loops can be all saved in 2XB303 iOS Files folder, also incrementally the Export section . You can keep them stored in there for later if you have a nice sounding loop you want to keep. You can access them in iOS Files to copy , paste , rename etc. Also fixed some other bugs

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Last verified
31 Jul 2026
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