# Crystal Synth XT vs GSDSP Quantum Filter

The clearest difference is price: Crystal Synth XT at $4.99 against GSDSP Quantum Filter's $14.99. Crystal Synth XT also leads on ratings volume (20 vs 3). GSDSP Quantum Filter's advantage is review sentiment (100% vs 78%) and update cadence (every 5 weeks vs every 4 months). On rating, ads, in-app purchases and monetization model there is nothing between them.

Crystal Synth XT costs $4.99 and GSDSP Quantum Filter $14.99 up front. Neither carries in-app purchases, so what you see is what you pay.

On the App Store both sit at effectively the same score — 4.9 for Crystal Synth XT against 5.0 for GSDSP Quantum Filter. That said, the two scores are not equally well evidenced: Crystal Synth XT has 20 ratings behind it against 3, so its average is the more settled of the two. Written reviews are what separate them: 78% of Crystal Synth XT's written reviews are positive against 100% of GSDSP Quantum Filter's.

Crystal Synth XT ships an update every 4 months, GSDSP Quantum Filter every 5 weeks. The most recent releases landed on September 21, 2026 and September 22, 2026 respectively.

## The numbers

| Metric | Crystal Synth XT | GSDSP Quantum Filter |
| --- | --- | --- |
| Price | **$4.99** | $14.99 |
| Rating | [4.9 (20 ratings)](https://appshunter.io/ios/app/crystal-synth-xt/id408288370/reviews) | **[5.0 (3 ratings)](https://appshunter.io/ios/app/gsdsp-quantum-filter/id6498711920/reviews)** |
| Number of ratings | **20** | 3 |
| Positive reviews | 78.4% of reviews | **100.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 5 weeks** |
| Monetization | Paid | Paid |
| Size | 36 MB | 77 MB |
| Requires iOS | **11.0** | 12.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Green Oak Software](https://appshunter.io/developer/355342717) | [Gustav Scholda](https://appshunter.io/developer/1642323227) |

## What reviewers say

### Crystal Synth XT

[App page](https://appshunter.io/ios/app/crystal-synth-xt/id408288370)

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:** macOS Compatibility

**In-app purchases:** none

**What reviewers like**

- 🎶 Fantastic sound quality
- 💡 Innovative breed function
- 🎛️ Deep sound design capabilities
- 🎹 Versatile synth
- ✨ Unique and creative sounds

**What reviewers complain about**

- 🐛 Occasional crashes
- ⚠️ Preset system issues (folders, access)
- 🐌 Outdated interface
- 🔌 Lacks AUv3 support (frequently requested)
- 🔊 Crackling/popping sounds

**Reported bugs**

- App not working, splash screen disappears
- Screen in background
- Envelope points not moving
- Breed fan not working properly
- Crashing on launch

**Requested features**

- AUv3 support
- Update to an AU3 standard
- Newer interface
- Fix breed fan access to all presets
- Fix preset system variations between devices


### GSDSP Quantum Filter

[App page](https://appshunter.io/ios/app/gsdsp-quantum-filter/id6498711920)

This audio effect plugin offers analog-modeled filters with flexible routing and dynamic modulation for creative sound design. It provides extensive control over tone shaping and complex filtering with various filter types and configurations.

**Highlights:** Analog-modelled filters, 11 filter modes, Series and parallel routing, Dynamic modulation support, Stereo and dual mono modes, MIDI control integration

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Crystal Synth XT free?

Crystal Synth XT costs $4.99, with no in-app purchases.

### Is GSDSP Quantum Filter free?

GSDSP Quantum Filter costs $14.99, with no in-app purchases.

### Which has better reviews, Crystal Synth XT or GSDSP Quantum Filter?

GSDSP Quantum Filter is rated higher. Crystal Synth XT averages 4.9 out of 5 from 20 ratings, while GSDSP Quantum Filter averages 5.0 from 3 ratings.

### Do Crystal Synth XT or GSDSP Quantum Filter have ads?

Neither Crystal Synth XT nor GSDSP Quantum Filter shows ads.

### Which is updated more often, Crystal Synth XT or GSDSP Quantum Filter?

Crystal Synth XT ships an update every 4 months, and GSDSP Quantum Filter every 5 weeks. Most recently, Crystal Synth XT was updated on September 21, 2026 and GSDSP Quantum Filter on September 22, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*