Comparison

Crystal Synth XT vs S

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

Head to head
About

Crystal Synth XT

Create lush, evolving soundscapes with a powerful semi-modular synthesizer for mobile devices. Explore subtractive and FM synthesis, extensive modulation, and built-in effects. Share sounds with the desktop version and connect MIDI keyboards for a full hardware synth experience.

Highlights
  • Semi-modular synthesis engine
  • Subtractive and FM synthesis
  • Extensive modulation control (>90 parameters)
  • Multi-stage envelopes with graphical editors
  • Tempo-synced envelopes, LFOs, and delays
  • Built-in effects (chorus, flanger, echo)
  • MIDI keyboard input and virtual MIDI support
Features
Read full description

Crystal Synth XT is a full featured semi-modular synthesizer, ideally suited to creating lush evolving soundscapes. Crystal VST has long been a popular synthesizer on the desktop. Crystal Synth XT brings that same powerful synthesis engine to the iPad and iPhone. Crystal Synth XT features MIDI keyboard input via Apple's camera adapter and sharing of sounds with the desktop version of Crystal. == Features == Browse through the included sounds and use the 2 octave keypad or keyboard to trigger notes to produce evolving, rhythmic, or melodic sounds. Create your own sounds with a single button press using the breed feature. When using an iPad, you can delve into a tweaker's dream by using the extensive editing features to sculpt sounds to your heart's content (editing features are only available when used on an iPad). Crystal features both subtractive synthesis and frequency modulation (FM) synthesis. It offers abundant modulation control with over 90 parameters which may be modulated, multi-stage envelopes with graphical editors, extensive tempo sync of envelopes/lfo rates/delay times, built-in effects for chorus/flanging/comb filtering/echoes, and a band splitter for effects processing by frequency band. Not only that, Crystal has wave sequencing and granular synthesis. The musical applications for Crystal are literally boundless. == MIDI == With MIDI keyboard input, you can connect a MIDI keyboard to your iPad or iPhone and play Crystal Synth XT like a hardware synth. == Virtual MIDI == Use virtual midi to play Crystal Synth XT from a midi controller app. Use the Settings app to turn on the Background Audio mode to enable Crystal to play audio when in the background. You can then play Crystal from a midi controller app which supports virtual midi. == Sharing == With patch sharing you can create sounds on your iPad or iPhone while away from the studio, then transfer them to the desktop Crystal when you get back to the studio to use in recording projects. Or, create banks of sounds on the desktop Crystal, then transfer them to the iPad/iPhone Crystal to use in a live performance for a truly portable rig. Use Audio copy/paste to record your performance on Crystal and transfer that performance to another app. Or copy your recorded performance to your computer. == Inter App Audio and Audiobus == To use IAA or Audiobus to record into other apps, turn on Background Audio for Crystal Synth XT in the Settings app. See demonstration videos on the greenoak.com website. == Different Versions == If you don't need all the features of Crystal Synth XT, try the basic version of Crystal, also available in the app store from Green Oak Software. With the basic version you can browse sounds, play notes, and create new sounds, taking advantage of its powerful semimodular synthesis engine. The XT version adds features like MIDI keyboard input via the iPad's camera adapter, IAA/Audiobus, and patch sharing with the desktop version. Choose the app that is best for you! == Notes == Important note for iPhone users: Crystal Synth XT runs on both the iPad and the iPhone. Because of the limited screen space on the iPhone however, the editing pages, which contain the edit controls, are not available when running on that device. However, on the iPhone you can still browse sounds, play notes from the keypad, create new sounds with the Breed feature, modify patches with the Design feature, and share sounds with desktop Crystal VST. For videos and information about Crystal Synth XT, visit: http://www.greenoak.com

About

S

This semi-modular synthesizer app for iPad offers a hands-on sound design experience with a single-screen interface for intuitive patching. It delivers a warm, vintage sound inspired by 1970s synthesizers, featuring dual oscillators, resonant filters, and multiple modulation sources.

Highlights
  • Single-screen interface
  • Fast, hands-on patching
  • Vintage 1970s synth sound
  • Dual oscillators
  • Resonant ladder filter
  • Multiple modulation sources
Features
Read full description

S-Modular is a semi-modular synthesiser for iPad, designed for fast, hands-on patching without clutter. Everything is presented on a single screen, making sound design immediate and intuitive. Simply drag from one jack to another to create connections. S-Modular delivers a distinctive vintage sound inspired by classic 1970s synthesis — warm, rich, and full of character. Features Dual oscillators 24 dB/oct ladder filter Resonant high-pass and low-pass filters Two LFOs Four-step CV sequencer Four-track mixer Audio and CV splitter Two AHR envelope generators Delay effect

Screenshots

Crystal Synth XT1 screens
S2 screens

Verdict

The call

The clearest difference is review sentiment: Crystal Synth XT at 78% against S's 31%. Crystal Synth XT also leads on rating (4.9 vs 2.6) and iOS requirement (11.0 vs 15.6). S's advantage is price ($2.99 vs $4.99). On ratings volume, update cadence, ads and in-app purchases 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

Crystal Synth XT costs $4.99 and S $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Crystal Synth XT holds the better App Store score, 4.9 against 2.6. Both are backed by a comparable volume of ratings — 22 and 11 respectively. Written reviews point the same way: 78% of Crystal Synth XT's written reviews are positive against 31% of S's.

UpkeepUpdate frequency

Crystal Synth XT ships an update every 4 months, S every 7 months. The most recent releases landed on October 23, 2026 and October 7, 2026 respectively.

Scorecard4 real differences · 6 level
Crystal Synth XT versus S: the parameters behind the verdict, then further details
ParameterCrystal Synth XTS
Price$4.99$2.99 — better
Rating4.9 (22 ratings) — better2.6 (11 ratings)
Positive reviews78.4% of reviews — better31.3% of reviews
Number of ratings22 — better11
Update frequencyEvery 4 months — betterEvery 7 months
AdsNoNo
In-app purchasesNoNo
MonetizationPaidPaid
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS11.0 — better15.6
Further details — not scored
Size36 MB7 MB
Age rating4+4+
DeveloperGreen Oak SoftwarePaul Betowski

Customer experience

Crystal Synth XT

All ratings20 ratings
Positive95.0%
Neutral5.0%
Negative0.0%
Written reviews74 reviews
Positive78.4%
Neutral8.1%
Negative13.5%

S

All ratings11 ratings
Positive27.3%
Neutral27.3%
Negative45.5%
Written reviews16 reviews
Positive31.3%
Neutral25.0%
Negative43.8%

Bugs and requests

Crystal Synth XT

Reported bugs

15 issues
  • App not working, splash screen disappears
  • Screen in background
  • Envelope points not moving
  • Breed fan not working properly
  • Crashing on launch
Show 10 more
  • Clicks and crashes when adjusting parameters
  • Sounds distorted and buggy
  • Won't play any sounds
  • Crashes when hitting record
  • Play surface stopped responding
  • Crash when trying record function
  • Crackles and pops in sound engine
  • Audiobus fails, breaks up when switching apps
  • Preset name editing gone after iOS 7 update
  • Splash screen appears for a second, then disappears

Requested features

22 requests
  • AUv3 support
  • Update to an AU3 standard
  • Newer interface
  • Fix breed fan access to all presets
  • Fix preset system variations between devices
Show 17 more
  • AUv3 implementation
  • Update the envelope points
  • AUv3 standard transformation
  • Multiple instances in DAWs
  • Dark mode option
  • Advanced analytics dashboard
  • Fix preset name editing
  • In-app purchase for a second instance
  • Load/Save banks
  • Metronome or timer capability
  • Newer app icon
  • Redesign for Retina Display
  • Polyphony on iOS version
  • Recording facility
  • Keyboard option
  • Virtual MIDI support
  • Advanced patch editing on iPod version

S

Not enough reviews yet to summarise bugs or requests.

In-app purchases

None

Crystal Synth XT

No in-app purchases

None

S

No in-app purchases

Questions

Is Crystal Synth XT free?
Crystal Synth XT costs $4.99, with no in-app purchases.
Is S free?
S costs $2.99, with no in-app purchases.
Which has better reviews, Crystal Synth XT or S?
Crystal Synth XT is rated higher. Crystal Synth XT averages 4.9 out of 5 from 22 ratings, while S averages 2.6 from 11 ratings.
Do Crystal Synth XT or S have ads?
Neither Crystal Synth XT nor S shows ads.
Which is updated more often, Crystal Synth XT or S?
Crystal Synth XT ships an update every 4 months, and S every 7 months. Most recently, Crystal Synth XT was updated on October 23, 2026 and S on October 7, 2026.

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