M2DX vs Callback Freeverb

M2DX is a 6-operator, 32-algorithm FM synthesizer for iPhone, built from the ground up in pure Swift 6. Open it and play immediately — tap the built-in on-screen keyboard and start making sound with M2DX's own hand-crafted presets. No external hardware or MIDI controller is required. The FM engine is a bit-exact port of the open-source Dexed / msfa DSP, verified sample-for-sample against the reference. It is also compatible with the classic DX7 patch format: bring your own DX7-format .syx banks and play them alongside M2DX's originals. KEY FEATURES - Built-in on-screen keyboard with velocity and octave control — play standalone, no hardware needed - 6-operator, 32-algorithm DX7-style FM synthesis - M2DX's own original FM presets, plus DX7-format .syx bank import (bring your own) - A 6-stage FX chain: EQ, Drive, Chorus, Reverb, Stereo, Maximizer - Low-latency audio with AVAudioSourceNode direct rendering - AUv3 plug-in — use M2DX as an Audio Unit (AUv3) in compatible hosts OPTIONAL MIDI (not required to use the app) - Connect any MIDI controller over Bluetooth or USB if you have one - Native MIDI 2.0 — UMP with 16-bit velocity and 32-bit controllers - MIDI-CI Property Exchange — patch names appear on compatible controllers (for example, KORG KeyStage) - MIDI Learn for hands-on control MIDI 2.0 done natively, classic FM done faithfully. The FM engine is built on Dexed / msfa (Apache License 2.0). M2DX is an independent product and is not affiliated with, endorsed by, or sponsored by Yamaha Corporation. DX7 and Yamaha are trademarks of Yamaha Corporation. iOS 18 or later.

A classic algorithmic reverb effect based on the Freeverb algorithm by Jezar at Dreampoint. A Freeverb-style Schroeder/Moorer reverb based on the classic 8-comb + 4-allpass topology, with simplified controls and no stereo spread. This reverb creates lush, spacious ambience through a network of comb and allpass filters. Freeverb is widely used in electronic music production, ambient music, and sound design to add depth, space, and atmosphere to audio sources. The algorithm provides a smooth, musical reverb tail that works well on everything from vocals to synthesizers. This reverb only functions in mono and provides no stereo imaging, and the user can expect the same behavior as a classic Freeverb implementation otherwise.