Comparison

isxynth vs GSDSP Quantum Delay

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

Head to head
About

isxynth

This music effect plugin allows spectral cross synthesis and morphing between two input signals. It separates noise and tone components, offering controls for blending, freezing, and time-based delays. Gestures on controls can be recorded and played back for dynamic sound shaping.

Highlights
  • Spectral cross synthesis
  • Morphing between two input signals
  • Noise and tone component blending
  • Freeze control for spectral blurring
  • 3-second delay lines per input
  • Gesture recording and playback
Features
Read full description

isxysnth is spectral cross synthesis / morphing plugin it gets two input signals, splits each one into 2 parts containing noise and tone components and then allows morphing between all these elements. Freeze control allows spectral blurring-like effect for both input signals, two 3 second delay lines allow selection of different signal in time and also provide "freeze" effect you can process left and right channels on stereo source or use this effect as multi-input AUv3 - in that case it will use 2 stereo inputs. Standalone mode currently works only in "mono" mode - three XY controls set balance between tone and noise components, amount of freeze and set up morphing - both inputs have 3-second delay line; freeze button ("*") toggles off recording. - gestures on all the main controls (3 xy pads and two sliders) can be recorded and played back when appropriate button with ">" label is toggled on - in current version standalone app supports only mono (L + R as inputs I and II) processing

About

GSDSP Quantum Delay

This app offers a vintage-inspired stereo delay effect with advanced modulation, flexible filtering, and precise timing controls. It allows users to sculpt unique echo textures, from warm analog sounds to complex, evolving soundscapes.

Highlights
  • Vintage-inspired stereo delay
  • Deep modulation system
  • Flexible filtering (LPF, HPF, BPF)
  • Precise timing controls (BPM, ms)
  • Switchable stereo/dual mono modes
  • Advanced modulation sources (LFO, Random, Envelope)
Features
Read full description

A vintage-inspired delay supercharged with deep modulation, flexible filtering, and creative timing that pushes echoes into new dimensions. Classic Delay, Reinvented Quantum Delay takes the charm of a vintage stereo delay and fuses it with our next-level modulation system. Switch between the warm character of Tape mode and the pristine clarity of Fade mode, lock to BPM (including 5-tuplets) or dial in precise times in milliseconds. Use the Fine control for subtle push-and-pull micro-timing — or modulate your delay lines in ways traditional delays could only dream of. Sculpted Echoes Shape your repeats with switchable lowpass, highpass, and bandpass filters placed directly in the feedback path. Add modulation to create evolving tones, gentle movement, or drifting, frequency-shifting echoes. From warm analog-style rolls to shimmering, swirling textures, it’s all there. Feedback with Precision Control your delay tail behavior using either traditional % feedback or our modern dB-per-second decay system — ideal for predictable, musical decay even when the feedback path becomes complex. Enable Crossfeed for classic ping-pong stereo bounce, or push into Over-Feedback to create dense, self-building echoes that drift toward infinity. Stereo or Dual Mono Every section of Quantum Delay — delay, filter, and feedback — can switch between stereo and dual mono modes. Create tight, controlled stereo images or break them apart for wide, offset, unpredictable spaces. Dual mono modulation unlocks complex stereo interplay and beautifully asymmetric echoes. Modulation Without Limits Quantum Delay integrates our advanced modulation system, letting you modulate nearly anything: delay time, filters, feedback parameters, stereo controls, and more. Use LFOs, Random Generators, 2D modulators, Envelope Followers, Macros, and even chaotic systems to push your echoes far beyond traditional delay behavior. Or use our parameter randomisation feature to explore the plugin’s sound at random. Quantum Delay is an AUv3 audio effect plugin compatible with Logic Pro, AUM, Cubasis, GarageBand and many more. A Desktop version is also available for Windows and macOS (VST3 / AU / AAX). More information here: https://gs-dsp.com/products

Screenshots

isxynth3 screens
GSDSP Quantum Delay3 screens

Verdict

The call

The clearest difference is rating: GSDSP Quantum Delay at 4.8 against isxynth's 3.7. GSDSP Quantum Delay also leads on update cadence (every 5 weeks vs every 34 months) and ratings volume (17 vs 3). isxynth's advantage is price ($7.99 vs $14.99). On review sentiment, ads, in-app purchases and monetization model 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

isxynth costs $7.99 and GSDSP Quantum Delay $14.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

GSDSP Quantum Delay holds the better App Store score, 4.8 against 3.7. That said, the two scores are not equally well evidenced: GSDSP Quantum Delay has 17 ratings behind it against 3, so its average is the more settled of the two. Written reviews split almost evenly too, at 100% and 100% positive.

UpkeepUpdate frequency

isxynth ships an update every 34 months, GSDSP Quantum Delay every 5 weeks. The most recent releases landed on September 28, 2026 and September 22, 2026 respectively.

Scorecard4 real differences · 6 level
isxynth versus GSDSP Quantum Delay: the parameters behind the verdict, then further details
ParameterisxynthGSDSP Quantum Delay
Price$7.99 — better$14.99
Rating3.7 (3 ratings)4.8 (17 ratings) — better
Positive reviews100.0% of reviews100.0% of reviews
Number of ratings317 — better
Update frequencyEvery 34 monthsEvery 5 weeks — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidPaid
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS11.0 — better12.0
Further details — not scored
Size8 MB94 MB
Age rating4+4+
DeveloperAlexey NadzharovGustav Scholda

Customer experience

isxynth

All ratings3 ratings
Positive66.7%
Neutral0.0%
Negative33.3%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

GSDSP Quantum Delay

All ratings17 ratings
Positive94.1%
Neutral0.0%
Negative5.9%
Written reviews4 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

isxynth

No in-app purchases

None

GSDSP Quantum Delay

No in-app purchases

Questions

Is isxynth free?
isxynth costs $7.99, with no in-app purchases.
Is GSDSP Quantum Delay free?
GSDSP Quantum Delay costs $14.99, with no in-app purchases.
Which has better reviews, isxynth or GSDSP Quantum Delay?
GSDSP Quantum Delay is rated higher. isxynth averages 3.7 out of 5 from 3 ratings, while GSDSP Quantum Delay averages 4.8 from 17 ratings.
Do isxynth or GSDSP Quantum Delay have ads?
Neither isxynth nor GSDSP Quantum Delay shows ads.
Which is updated more often, isxynth or GSDSP Quantum Delay?
isxynth ships an update every 34 months, and GSDSP Quantum Delay every 5 weeks. Most recently, isxynth was updated on September 28, 2026 and GSDSP Quantum Delay on September 22, 2026.

Other comparisons