# FD-1 Filter Delay

> Semi-modular audio effect plugin with filter, delay, and modulation. (iPhone/iPad app by Kai Aras.)

- Source: https://appshunter.io/ios/app/fd-1-filter-delay/id1448696965 (this page in markdown: same URL + `.md`)
- Developer: [Kai Aras](https://appshunter.io/developer/370820899)
- Category: Music
- Price: $9.99
- Rating: 4.60/5 from 32 App Store ratings · 9 written reviews indexed
- Age rating: 4+
- Requires: iOS 9.0 · 61 MB
- Languages: American English
- Released: 2019-11-07
- Data updated: 2026-09-12
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/fd-1-filter-delay/id1448696965/reviews.md

## What is FD?

FD-1 is a Semi-Modular Effect Plugin including dedicated Filter, Delay and Modulation sections. 

At it's core, FD-1 is designed to create filter rythms and grooves by first sending the signal through a modulated filter section before feeding it to a delay stage but it goes much further than that. 

Built-in Step Sequencer and Low Frequency Oscillator serve as modulation sources and are ideal for creating rythmic filter sequences either free running or tempo-synced to a host application. 

However, due it's semi modular nature, not just filter cutoff but every control within FD-1 can be a modulation target allowing for an increased range effects and combinations ranging from Chorus and Flanger type effects over Analog and Tape Style echos to complex Stutter and Repeat effects. 


Overview:
- VA Multi Mode Filter with 2 & 4 Pole options
- Digital Stereo Delay with Tempo Sync and Time Range Control
- Analog Style Step Sequencer 
- Low Frequency Oscillator 
- Easy to use Mod Matrix 
- Input Low-Cut and Drive Controls
- Individual Return Levels for Filter and Delay

Connectivity:
- Standalone
- AUv3
- IAA
- AudioBus (Filter)

MIDI:
- Tempo Sync
- CC Control

Requirements:
- iOS9+ 
- iPad 4th generation or newer

## Key features

- Semi-modular effect plugin
- Modulated filter section
- Delay stage
- Step sequencer
- Low Frequency Oscillator
- Mod matrix
- Tempo sync

## Recent user reviews (9 of 9)

All indexed reviews: https://appshunter.io/ios/app/fd-1-filter-delay/id1448696965/reviews.md

### 5/5 — Love this effect

*2025-08-27*

Great app. 5 out of 5, with one exception. When loading in AUM it won’t. The icon goes red, everytime, even when reloaded. Maybe just me?

### 5/5 — Fantastic

*2024-12-10, version 1.1.2*

I’ve had this for years and has been rock solid. One of my go to effects.

### 1/5 — abandonware :(

*2024-05-28*

many unanswered emails later i am pretty sure this app is not being maintained. if it doesnt work in aum or loopy pro it doesnt work dudes.

### 2/5 — Unusable in Nanostudio

*2021-10-03*

Not because it doesn’t work, but the interface isn’t scaled correctly, so the knobs overlap each other making them very hard to tweak. Don’t know if this is the case for every daw, I only tried Nanostudio.

### 5/5 — Big knob issue

*2020-06-02, version 1.1*

Unnecessarily big knobs in the middle dwarf the sequencer and even crowd out the section headings at the top of the interface making it look like a badly cropped screenshot.  
Effete concerns aside, it sounds fantastic, hence the 5 stars (and I will probably be equally generous if I ever get around to reviewing the other apps of his I own).  Wide range of sound shaping capabilities that can either utterly dominate and warp your sound or just complement it by dancing like a drowsy winged herd of fireflies in a yonder glade.   Well that’s how I use it anyway...

### 1/5 — Very Buggy

*2020-04-22*

This app is infested with bugs.  Virtually unplayable.  The knobs either don’t turn at all, or they swing wildly to and fro like they have a mind of their own. I’ve tried unloading and reloading, no change.  I am using this in AUM.  This is so incredibly frustrating, to spend money on an app that clearly is having major performance issues.  Hello, developer??? Please fix your app, or give it away free!

### 4/5 — please update with the same love as for ShockWave.

*2020-02-01*

Absolutely fanatical app. And now please update with the same love as for ShockWave. Thank you very much.

### 5/5 — Blue Beauty

*2019-11-14, version 1.0.1*

Alike all of Kai's apps, this is a real beauty both inside and out. I love it especially on drums and other percussive sounds... gives them an instant change in character. Super easy to create and save your own presets, so I've been at it ✊🏽 Gonna be a go-to 😎

### 5/5 — An excellent effect for sound designers and groove manipulators

*2019-11-08*

Really well thought out plug-in from Numerical.  It took me a minute to realize all that I could achieve with this effect once you wrap your head around it it’s super powerful.  I still don’t fully understand the sequencer portion but I’m having fun figuring it out.  Some of the knobs are a little sticky in auv3 but that’s a simple bug fix.  Well done on another dynamic effect, Kai.

## Frequently asked questions about FD

### What is FD-1?

FD-1 is a semi-modular audio effect plugin for iOS that combines filter, delay, and modulation sections. It's designed to create rhythmic filter sequences and a wide array of complex audio effects.

### What devices does FD-1 support?

FD-1 is compatible with iPhone, iPad, and iPod touch devices running iOS 9 or newer. It requires at least an iPad 4th generation or newer.

### How much does FD-1 cost?

FD-1 is a paid application, available for $4.99. There are no in-app purchases or subscriptions associated with this app.

### Does FD-1 have ads?

No, FD-1 does not contain advertisements. It is a premium application that offers an ad-free experience.

### What are the main modulation sources in FD-1?

FD-1 features a built-in Step Sequencer and a Low Frequency Oscillator (LFO) as its primary modulation sources. These can be used to create rhythmic filter sequences or tempo-synced effects.

### Can FD-1 sync to a host application's tempo?

Yes, FD-1 supports tempo sync for its step sequencer and delay. This allows it to align rhythmically with your host application, making it ideal for music production workflows.

### What kind of audio connectivity does FD-1 offer?

FD-1 offers multiple connectivity options, including standalone operation, AUv3, Inter-App Audio (IAA), and AudioBus. This flexibility allows it to be integrated into various iOS music production setups.

### How often is FD-1 updated?

FD-1 was last updated on September 24, 2020, with version 1.1.2. While the last update was in 2020, the app has maintained a high user rating of 4.7 stars.

## Version history (last 4 releases)

### 1.1.2 — 2020-09-24

- Fixed an issue where presets would not load when running on iOS14

### 1.1 — 2020-03-23

- Added iPhone support
- Added iOS9 support
- Added X-Ray mode
- Minor visual tweaks
- Sequencer controls can now be midi mapped
- Fixed an issue where the plugin could crash when modulating delay time in tempo sync mode
- Fixed an issue where it wasn't possible to connect BLE MIDI devices when running standalone
- Fixed an issue where modulating delay time with tempo sync active could generate glitches 
- Fixed an issue where mod routing popover would not work properly in some cases
- Fixed an issue where lfo frequency and delay time would not restore properly when using tempo sync

### 1.0.1 — 2019-11-14

- Redesigned the routing menu for easier access (remember you can tap and hold a control to get a routing menu)
- Changed the master output level to filter level to allow for additional control of the final effect mix 
- Fixed AudioBus/IAA support
- Fixed Audio Glitches in NanoStudio 2
- Fixed an issue where playing back recored parameter automation would not update the UI 
- Fixed an issue where the sequencer would not resume properly after pausing host transport
- Fixed an issue where lfo square waveform could generate glitches in some cases 
- Fixed an issue where modulating very short delay times could genrate glitches in some cases

### 1.0 — 2019-11-07

No release notes.

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## More apps by Kai Aras

- [MIDIBrute](https://appshunter.io/ios/app/midibrute/id1010753735)
- [RP-1 Delay](https://appshunter.io/ios/app/rp-1-delay/id1079530569)
- [RF-1 Reverb](https://appshunter.io/ios/app/rf-1-reverb/id1097763239)
- [VC-1 Chorus](https://appshunter.io/ios/app/vc-1-chorus/id1130683829)
- [Italizer](https://appshunter.io/ios/app/italizer/id1133091743)
- [VOLT Synth](https://appshunter.io/ios/app/volt-synth/id1185984394)

All apps by Kai Aras: https://appshunter.io/developer/370820899

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-12.*