Comparison

2XB303 Acid Bass Loop Maker vs SUS4 Loop Builder

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

2XB303 Acid Bass Loop Maker

Create electro melodies and acid techno basslines with this creative bass synth sequencer. Features live control for triggering sequences and synth pads, random generation, and extensive sound shaping options. Export your audio loops easily.

Highlights
  • Bass synth sequencer
  • Live control for sequences and pads
  • Audio loop recording and export
  • Random sequence generation
  • Tweakable synth parameters
  • MIDI and Ableton Link syncing
  • Global effects: Overdrive, Compression, Echo
Features
Read full description

A creative bass synth sequencer for creating electro melodies or dirty phat & funky pure acid techno 303 style basslines. With LIVE CONTROL feature to trigger and transpose both sequences and new synth pad layer. Record and export your audio loops. Inspired by the acid house music scene. An IOS exclusive, compared to a modern equivalent to Rebirth (Rebirth was a popular tb - 303 clone a decade ago). Look at the video tutorial for a how-to guide. Listen to what you can create easily with 2XB303. Create electro, house, techno, edm or synth sequences using standard step functions as seen on various sequencers like the Roland SH 101 synthesizer.  Built in pad layer than follows pitch. Transpose and trigger sequence even with MIDI Your synth sequences can also be generated randomly, shuffled or modify just notes. Easily capture whatever you hear and export to AudioShare, Audio-Copy, Email or iTunes Shared Folder. Support for Audiobus 3 routing, Ableton Link, IAA (Inter App Audio) Tweaking cut-off & decay Env-Mod & glide & accent etc for that classic sweet-spot acid growl Tap to dials to swipe up & down for fine adjustment of knobs. The sound was first compared to a Cyclone TT - 303 synthesizer & tweaked to extend sound shaping beyond a just bass maker. Waves have optional harmonic version, noise, LFO, glide speed & PHAT/ BASS, and great effects. This is designed to give pure electro music creativity beyond an acid synth 303 bass maker to create dynamically fluctuating overlaying electronic patterns. A good addition to any electro, drum and bass, acid, techno, house and any other EDM fans LIVE CONTROL feature: Use the keyboard for the following cool tricks: [Sequence/Control/Transpose]: Transpose both channels simultaneously while playing. Now ability to trigger sequence too, with synth pad layer. (optional and 22 sounds) [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. MOD: LFO auto control low pass CUT-OFF and/or PITCH. The pitch level can give a vintage synthesiser effect subtly detuning with low SPEED or faster for chaotic random pitches. EFFECTS (Global/master are in yellow.) OVERDRIVE, COMPRESSION adjusts threshold, ratio, & gain. This is a global effect. ECHO tempo synced with feedback & wetness. SAVE ALL. When not playing, save to memory. SYNCING Ableton Link syncs with apps .Enable for precise timing without syncing. Press LINK button at the bottom for settings. MIDI sync with External, Virtual or Audiobus. 2XB 303 can be master or slave. ( any simple class-compliant USB should work but some may need to be power assisted) Virtual MIDI In is always on. If you send from another app AND receive MIDI clock then you will be receiving both MIDI CLOCKS. Choose only one unless you want double tempo (which can be interesting). While Ableton Link is enabled you can send clock. This means you can use one app to control 2XB303 synth alongside external hardware sequencers MIDI note data is sent out on each channel AUDIO Record a fixed length, default to 32 steps. Can be changed in settings. Arming the sampling with CAPTURE (flashing). Starts at counter 1 (ON). PLAY CAP to listen to your super cool sampled acid synthesiser loop. Audiobus 3 and IAA (Inter App Audio) Support. Route audio to mix or record into other applications Audio can be routed via IAA into apps like Apple's Garageband. Garageband will also sync your sequence for excellent multi-track recording. To save you press "Save all", it then flashes. Now choose destination ("!" means its occupied ) then press "Save All" to confirm.

About

SUS4 Loop Builder

Features
Read full description

Build a song one loop at a time. A looper and multitrack overdub tool for guitar, vocals and anything with a mic. Layer parts, keep them in time, and export stems when the idea is worth finishing. SUS4 Loop Builder is a multi-track looper for building song ideas from scratch. Record a bass line into the first layer, layer a chord progression over it, add a melody on top, and keep going until the idea has a shape. Each layer has its own level and effect controls so the mix develops as you build. When you have something, export the full mix or individual stems to your DAW for proper production. The loop library saves your builds so you can come back to them, reference them, or share a stem with a collaborator. • Multi-track looping — record and layer on top of previous loops • Per-layer level and effects controls • Loop library for saving and revisiting ideas • Stem export — export individual layers or the full mix • Multi-track export to your DAW • Subscribe monthly, or unlock the full SUS4 suite forever: unlimited loops, multi-track export, per-layer effects, and the full loop library All recording stays on your device. No audio is uploaded. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

2XB303 Acid Bass Loop Maker4 screens
SUS4 Loop Builder4 screens

Verdict

The call

The clearest difference is price: SUS4 Loop Builder at Free against 2XB303 Acid Bass Loop Maker's $3.99. 2XB303 Acid Bass Loop Maker's advantage is in-app purchases (none vs 2) and update cadence (every 10 days vs monthly). On ads, device support and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

SUS4 Loop Builder is free to download; 2XB303 Acid Bass Loop Maker costs $3.99 up front. SUS4 Loop Builder sells 2 in-app purchases, starting at $0.99 per month. 2XB303 Acid Bass Loop Maker asks for nothing beyond the download.

UpkeepUpdate frequency

2XB303 Acid Bass Loop Maker ships an update every 10 days, SUS4 Loop Builder monthly. The most recent releases landed on October 19, 2026 and October 12, 2026 respectively.

Scorecard3 real differences · 7 level
2XB303 Acid Bass Loop Maker versus SUS4 Loop Builder: the parameters behind the verdict, then further details
Parameter2XB303 Acid Bass Loop MakerSUS4 Loop Builder
Price$3.99Free — better
Rating4.7 (57 ratings) — better—
Positive reviews66.7% of reviews—
Number of ratings57 — better—
Update frequencyEvery 10 days — betterMonthly
AdsNoNo
In-app purchasesNo — betterYes
MonetizationPaid—
DevicesiPhone, iPad, iPodiPhone, iPad, Mac
Requires iOS15.6 — better16.0
Further details — not scored
Size16 MB20 MB
Age rating4+4+
DeveloperRob WilmotThePaulSmith

In-app purchases

None

2XB303 Acid Bass Loop Maker

No in-app purchases

2 purchases

SUS4 Loop Builder

Subscriptions2
  • SUS4 Loop Builder Pro Monthly$0.991 Month
  • SUS4 All-Access7 Days trial$4.991 Month

Questions

Is 2XB303 Acid Bass Loop Maker free?
2XB303 Acid Bass Loop Maker costs $3.99, with no in-app purchases.
Is SUS4 Loop Builder free?
SUS4 Loop Builder is free to download, with in-app purchases available.
Do 2XB303 Acid Bass Loop Maker or SUS4 Loop Builder have ads?
Neither 2XB303 Acid Bass Loop Maker nor SUS4 Loop Builder shows ads.
Which is updated more often, 2XB303 Acid Bass Loop Maker or SUS4 Loop Builder?
2XB303 Acid Bass Loop Maker ships an update every 10 days, and SUS4 Loop Builder monthly. Most recently, 2XB303 Acid Bass Loop Maker was updated on October 19, 2026 and SUS4 Loop Builder on October 12, 2026.

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