Phase Modulator vs BitDecay
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Phase Modulator
This app generates complex audio textures and tones by manipulating the phase of a carrier oscillator with a modulating signal. It offers two distinct modes: internal oscillator-to-oscillator modulation or using your audio input as the modulation source. Explore a wide range of sonic possibilities from shimmering harmonics to dense, inharmonic spectra.
- Phase modulation synthesis
- Internal carrier and modulator oscillators
- Audio input as modulation source
- Adjustable carrier and modulator frequencies
- Modulation index control
- Selectable oscillator waveforms
- Amplitude tracking of input audio
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PHASE MODULATOR Phase modulation perturbs the running phase of a carrier oscillator with a modulating signal. Sweeping the phase back and forth generates a series of sidebands above and below the carrier, spaced by the modulator frequency, whose number and strength grow with the Index. This is the same technique behind classic FM synthesis: small index values add a little harmonic shimmer; large values produce dense, clangorous, often inharmonic spectra. The carrier you hear is always an internal oscillator. What changes between modes is where its phase modulation comes from. ------ CONTROLS: CAR FREQ Frequency of the carrier oscillator, 20 Hz to 20 kHz. This is the audible tone in both modes. CAR AMP Level of the carrier oscillator before the Output gain. MOD FREQ Frequency of the internal modulator oscillator, 20 Hz to 20 kHz. Active in Osc + Osc only. The carrier-to-modulator frequency ratio sets the harmonic character: integer ratios give harmonic, pitched tones; non-integer ratios give bells and metallic, inharmonic results. In Input + Osc the modulator comes from your audio instead, so this control is inactive. MOD AMP Level of the modulation source before it reaches the phase. Together with Index it sets how far the carrier phase is pushed; think of it as a trim ahead of the Index multiplier. INDEX Modulation index, 0 to 10. The headline control: peak phase deviation in radians equals Index times the modulation signal. At 0 the carrier passes clean; raising it brings in progressively more sidebands and brightness. OUTPUT Makeup gain after the effect, -24 dB to +36 dB. No limiter follows this stage, so watch your meters when boosting. WAVEFORM Carrier oscillator shape: Sine, Saw, Triangle, or Square. Sine is the classic FM voice. The richer shapes already contain harmonics, so phase modulating them produces denser spectra and reacts more aggressively to Index. MOD WAVE Modulator oscillator shape (Osc + Osc mode only): Sine, Saw, Triangle, or Square. Changes the harmonic character of the modulation itself. In Input + Osc mode the modulation comes from your audio, so this picker is inactive. FOLLOW Input + Osc only. With Follow On (the default) the carrier tracks the amplitude of your incoming audio: it speaks only while signal is present and falls silent when the input does, so the plugin behaves like an effect rather than a constant tone. With Follow Off the carrier runs continuously at its set level regardless of input, which suits drones and sustained textures. In Osc + Osc there is no input to follow, so this control is inactive. ----- MODES: OSC + OSC Both carrier and modulator are internal oscillators, set by Car Freq and Mod Freq. Classic two-operator FM with no input required, good for bells, electric pianos, and metallic drones. INPUT + OSC Your track's audio becomes the modulation source, perturbing the phase of the internal carrier oscillator. Note that what you hear is the carrier shaped by your audio, not the audio itself passed through; the input controls the timbre rather than being processed in place. Mod Freq does not apply in this mode. This is the default mode. ------ A NOTE ON ALIASING Phase modulation can scatter energy well above Nyquist, so the effect runs internally at four times the host sample rate and filters on the way back down. At extreme Index settings with the saw or square carrier some residual aliasing can remain; lower the Index or the carrier frequency if you hear gritty, detuned overtones.
BitDecay
This creative audio effect simulates the character of aging hardware, unstable digital systems, and worn media. It introduces dynamic instability and evolving imperfections to transform pristine audio into lo-fi textures, degraded samplers, or entirely new sound design landscapes.
- Creative digital degradation processor
- Bit crushing and sample rate reduction
- Dynamic instability and clock imperfections
- Musical tone shaping
- Progressive signal erosion controls
- AUv3 support
- Single-page interface
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Some digital processors sound broken. Bit Decay sounds like they're breaking. Bit Decay is a creative degradation effect that recreates the character of aging hardware, unstable clocks, failing digital systems, worn media, and collapsing fidelity. Instead of simply reducing bit depth and sample rate, Bit Decay introduces movement, instability, and evolving imperfections that bring static digital destruction to life. Shape classic lo-fi textures, degraded samplers, damaged tape transfers, corrupted audio artifacts, and entirely new sound design landscapes. From subtle vintage coloration to complete digital collapse, Bit Decay gives you precise control over how pristine audio slowly falls apart. Whether you're producing electronic music, processing drums, designing cinematic textures, mangling synths, or adding character to vocals, Bit Decay delivers degradation with personality. Features • Creative digital degradation processor • Bit crushing and sample rate reduction • Dynamic instability and clock-style imperfections • Musical tone shaping • Progressive signal erosion controls • AUv3 support for iPad and Mac hosts • Fast workflow with a simple single-page interface
Screenshots
Verdict
The clearest difference is device support: BitDecay at 4 against Phase Modulator's 2. BitDecay also leads on iOS requirement (12.0 vs 17.0). Phase Modulator's advantage is price ($1.99 vs $2.99). On rating, ratings volume, 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
Phase Modulator costs $1.99 and BitDecay $2.99 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 — 5.0 for Phase Modulator against 5.0 for BitDecay. Both are backed by a comparable volume of ratings — 2 and 1 respectively.
| Parameter | Phase Modulator | BitDecay |
|---|---|---|
| Price | $1.99 — better | $2.99 |
| Rating | 5.0 (2 ratings) | 5.0 (1 ratings) |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | 2 — better | 1 |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad | iPhone, iPad, iPod, Mac — better |
| Requires iOS | 17.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 8 MB | 17 MB |
| Age rating | 4+ | 4+ |
| Developer | Callback Audio, LLC | Jeremy Phillips |
Customer experience
Phase Modulator
BitDecay
In-app purchases
Phase Modulator
No in-app purchases
BitDecay
No in-app purchases









