OPx-4

Name: OPx-4
Price: 149 USD
Author: AIR Music Technology

by AIR Music Technology · Synth · Four-operator FM synth

Not rated yet

OPx-4 is a four-operator FM synth with a 4x4 FM matrix, a 32-slot modulation matrix and 23 filter types.

It includes AIR's effects and a 10-day trial, and costs $149.

Best for: Keys & Synths, Bass, Sound Design. Genres: Electronic & EDM, Pop, Ambient & Cinematic.

Keywords: FM, drum machine, modulation matrix, airy, basses, electric piano, metallic, plucks, sound design, subtractive, cinematic, evolving, pads, tempo-synced.

What it does

OPx-4 is AIR's four-operator FM synth. The developer's aim is to make FM synthesis approachable for people without deep FM knowledge, through an "easy-to-understand control layout" and subtractive-style filters after the FM engine.

FM engine: four operators routed through a 4x4 FM matrix for setting how the operators modulate each other.
Per-operator shaping: each operator has its own ADSR envelope plus pulse width, formant, FM filtering and FM shaping controls for moving beyond plain sine tones.
Filters: a dual-mode filter path with 23 filter types, which lets you treat FM tones like a subtractive synth.
Envelopes and LFOs: six envelopes with tempo-synced looping, two LFOs and two ramps.
Modulation matrix: 32 slots for routing envelopes, LFOs and controllers to FM amounts and other parameters.
Effects: three insert and two global effects slots, drawing on 27 AIR effects including reverb, delay, distortion, modulation, EQ and amp simulation.
MPC and Force: runs on Akai MPC (2.11+) and Force (3.2+) hardware as well as in desktop hosts.

The current version is 1.2.0.8, and a 10-day free trial is available.

Source: AIR Music Technology product page

When to use it

OPx-4 is a dedicated FM instrument: four operators, a full matrix and a filter section, with a layout meant to make FM less abstract. Unlike Phase Plant and Pigments 7, which offer FM as one engine among many, or Serum 2, which can apply FM between its wavetable oscillators, it puts FM first. That focus suits bells, electric pianos, plucks and metallic basses, where FM is at its best. Its other selling point is MPC and Force support, which the big desktop synths don't have. If you mainly want wavetable or hybrid sound design with some FM on the side, Serum 2 or Vital (free) cover more ground.

Best for: FM bells, electric pianos, plucks, metallic basses and evolving pads, especially on MPC or Force.
Genres: electronic, synth-pop, hip-hop and cinematic.
Look elsewhere if: you want a strict six-operator DX7-style instrument, or broad hybrid synthesis (Phase Plant, Pigments 7, Serum 2).

What producers say

There is very little published user feedback on OPx-4, and the one KVR user review is strongly negative about the workflow rather than the sound engine.

KVR users rate it 1 out of 5 from a single review (version 1.2.0.8), calling it the most disappointing synth purchase the reviewer had made.
Criticisms: that reviewer found programming tedious, reported labelling errors and confusing unipolar/bipolar behaviour in the modulation matrix, and noted presets can't be switched by MIDI Program Change.
Sweetwater lists it but has no customer reviews yet.

Where to buy

Best Service: $149
AIR Music Technology: $149 (list price from KVR Audio; airmusictech.com shows prices only in its shop)
PluginFox: $149
AudioDeluxe: $149
Plugin Boutique: $149

Tutorials and reviews

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