Comparison

Transfer Function vs ToneGen PlusMinus

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

Head to head
About

Transfer Function

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
Read full description

Transfer Function is a dual-FFT acoustic analysis app that is used for sound system audio analysis. Since it can operate with music as the signal source, it can be used during a musical performance to monitor and turn the system equalization during the show. Transfer function includes: -- Magnitude Graph -- Phase Graph -- Coherence Plot -- Delay Finder -- Signal Generator Normally a transfer function requires a two-channel interface, and that is true with this one, also, if you want to use it with program material (music). However, you can use our Transfer Funciton with the internal iOS microphone, if you can send the pink noise generator output to the sound system input. In this configuration, the internal generator is routed back to the input as the reference channel. You can measure delay, magnitude, and phase using this setup. When you use Transfer Function with a two-channel audio interface to run, such as the Studio Six Digital iAudioInterface2, then you can also use any audio source as the test signal, including music. See our website for more information.

About

ToneGen PlusMinus

Features
Read full description

Signal generator for identifying audio frequencies by manually matching the pitch. Identifying feedback frequencies rapidly and precisely as an audio tech in a concert situation is a crucial function. Sometimes the feedback is intermittent, or only happens for an instant. For decades I and others have used the procedure of holding a heard pitch in my head and them matching it with some sort of tone generator. There are several iPhone apps that I have used, holding the phone up to my ear to hear the tone. They all have either a dial or a slider to set the pitch. An endless dial can be very precise, but is difficult to operate without looking at the screen. A slider is resolution limited by the length on the screen and so can't be precise. ToneGen PlusMinus uses a novel pitch setting UI which I invented 20 years ago for a Palm III app I wrote. It is very easy to rapidly and precisely match a frequency across it's range of 30 Hz to 10 kHz, without looking at the screen at all. The farther up or down from center your touch slides, the faster the pitch changes. Slide back to center and it stays stable.

Screenshots

Transfer Function3 screens
ToneGen PlusMinus1 screens

Verdict

The call

The clearest difference is price: ToneGen PlusMinus at Free against Transfer Function's $49.99. ToneGen PlusMinus also leads on in-app purchases (none vs 1). On update cadence, 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

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

UpkeepUpdate frequency

Transfer Function ships an update every 6 months, ToneGen PlusMinus every 3 months. The most recent releases landed on September 24, 2026 and September 14, 2026 respectively.

Scorecard2 real differences · 8 level
Transfer Function versus ToneGen PlusMinus: the parameters behind the verdict, then further details
ParameterTransfer FunctionToneGen PlusMinus
Price$49.99Free — better
Rating3.0 (2 ratings) — better—
Positive reviews25.0% of reviews—
Number of ratings2 — better—
Update frequencyEvery 6 monthsEvery 3 months — better
AdsNoNo
In-app purchasesYesNo — better
MonetizationPaid—
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.0 — better15.1
Further details — not scored
Size33 MB39 MB
Age rating4+4+
DeveloperAndrew SmithDan Richardson

In-app purchases

1 purchases

Transfer Function

One-time1
  • Reference Curves Option$14.99
None

ToneGen PlusMinus

No in-app purchases

Questions

Is Transfer Function free?
Transfer Function costs $49.99, and also offers in-app purchases.
Is ToneGen PlusMinus free?
ToneGen PlusMinus is free to download, with no in-app purchases.
Do Transfer Function or ToneGen PlusMinus have ads?
Neither Transfer Function nor ToneGen PlusMinus shows ads.
Which is updated more often, Transfer Function or ToneGen PlusMinus?
Transfer Function ships an update every 6 months, and ToneGen PlusMinus every 3 months. Most recently, Transfer Function was updated on September 24, 2026 and ToneGen PlusMinus on September 14, 2026.

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