# Transfer Function vs D

The clearest difference is price: D at Free against Transfer Function's $49.99. D also leads on in-app purchases (none vs 1) and update cadence (every 2 months vs every 6 months). Transfer Function's advantage is iOS requirement (15.0 vs 17.0). On ads and device support there is nothing between them.

D is free to download; Transfer Function costs $49.99 up front. Transfer Function sells 1 one-off in-app purchase. D asks for nothing beyond the download.

Transfer Function ships an update every 6 months, D every 2 months. The most recent releases landed on September 24, 2026 and September 8, 2026 respectively.

## The numbers

| Metric | Transfer Function | D |
| --- | --- | --- |
| Price | $49.99 | **Free** |
| Rating | **[3.0 (2 ratings)](https://appshunter.io/ios/app/transfer-function/id824037130/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 25.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 6 months | **Every 2 months** |
| Monetization | Paid | — |
| Size | 33 MB | 33 MB |
| Requires iOS | **15.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Andrew Smith](https://appshunter.io/developer/291822462) | [Yamaha Corporation](https://appshunter.io/developer/353469356) |

## What reviewers say

### Transfer Function

[App page](https://appshunter.io/ios/app/transfer-function/id824037130)

This app performs dual-FFT acoustic analysis for sound systems, including music. It offers magnitude, phase, and coherence graphs, a delay finder, and a signal generator. It can operate with internal microphones or external audio interfaces for comprehensive sound system monitoring and equalization.

**Highlights:** Dual-FFT acoustic analysis, Magnitude, Phase, Coherence graphs, Delay Finder, Signal Generator, Music as signal source, Internal microphone support, Two-channel audio interface compatibility

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Reference Curves Option | $14.99 | one-time |


### D

[App page](https://appshunter.io/ios/app/d-remote/id6745768913)

**In-app purchases:** none


## Frequently asked questions

### Is Transfer Function free?

Transfer Function costs $49.99, and also offers in-app purchases.

### Is D free?

D is free to download, with no in-app purchases.

### Do Transfer Function or D have ads?

Neither Transfer Function nor D shows ads.

### Which is updated more often, Transfer Function or D?

Transfer Function ships an update every 6 months, and D every 2 months. Most recently, Transfer Function was updated on September 24, 2026 and D on September 8, 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.*