Review: SynthMaster

Review: SynthMaster

SynthMaster from KV331 Audio is an all-around semi-modular synthesizers with a very good sound and near endless possibilities for sound design.

It consists of two independent synth layers - each layer contains 2 oscillators, 4 modulators, 2 filters, 2 LFO's, 4 ADSR Envelopes, 2 MultiStage Envelopes, 2 2D Envelopes and 4 Keyscalers. KV331 Audio has been around since 2004 and continuously improved on functionality. I am very impressed by how often this synth is updated - not many competitors is up to speed here!


Comes with 1250 very impressive presets but you can buy preset bundles with even more presets - the Synthmaster Everything Bundle contains 29 preset banks with a total of 1800 presets.

The preset browser has search criteria for instrument type, preset attributes, music style or preset author. You will find all kinds of instruments here from warm bass to airy pads and screaming leads. Not to mention all the amazing arpeggiated and/or sequenced sounds.


Each layer has contains 2 oscillators and 4 modulators that can modulate the frequency, phase, amplitude or pulse width of the oscillators. However you can only see one at a time, you need to switch tabs to see the other oscillator/modulators.

SynthMaster supports several synthesis methods:

  • VA - Virtual Analog (subtractive)
  • Additive
  • Wavetable
  • Wavescanning
  • PM - Phase Modulation
  • FM - Frequency Modulation
  • PWM - Pulse Width Modulation
  • Ring Modulation
  • AM - Amplitude Modulation
  • Physical Modeling
  • SFZ Sample Playback synthesis

Each oscillator can have up to 8 voices that can be spread across the stereo spectrum and detuned to get a nice rich sound.

The Basic oscillator type support the usual Sawtooth, Sine, Triangle, Sawtooth, Pulse and Noise patterns but also Single Cycle Waveforms and SFZ instruments. You can even import your own WAV files and convert to SFZ to be used for oscillators.

The Additive oscillator type consist of eight basic oscillator types, where each can be set to different waveforms and can of course also be panned and detuned individually.

The Wavetable oscillator type contains up to 16 waveforms that are scanned in sequence either manually or by using one of the modulation sources

The Vector oscillator consist of four basic oscillator types, where you can mix between them using a XY-control.

Finally there is also an AudioIn "oscillator" type that turns SynthMaster into an FX processor or Vocoder.

The oscillators can be subjected to Amplitude Modulation, Phase Modulation or Frequency Modulation. There are four modulaters which are basicly four extra oscillators that can act as supercharged sub-oscillators, FM/PM modulation or they can modulate each other.


SynthMaster has a plenty of filters to select from:

  • Virtual Analog: LP, HP, BP, BS, LS, HS, PK, Multi and Dual.
  • Digital: The same as the Virtual Analog filter + Comb filter.
  • Moog style self-oscillating Ladder Filter: LP, HP, BP and BS.
  • Roland TB-303 style Diode Ladder Filter: LP.
  • SEM style State Variable Filter (SVF): LP, HP, BP, BS and Multi.
  • Korg MS20 style Bite Filter: LP and HP.

The digital filters support 12 and 24 db/octave slopes.

Each layer have two filters - again they are located on separate tabs.


SynthMaster has 6 global effects: Vocoder, Compressor, Chorus, Tremolo, Echo and Reverb.
Each layer has 5 insert effects: Distortion, Lo-Fi, Ensemble, Phaser and EQ.SynthMaster can also be used as effect plug-in.


SynthMaster has an impressive modulation architecture with 95 modulation sources and 650+ modulation targets! The modulation sources include:

  • ADSR Envelopes
  • LFO's
  • Pitch Bend
  • Aftertouch
  • MIDI Velocity
  • Easy Parameters
  • 2D Envelopes
  • Multistage Envelopes
  • KeyScalers
  • Vocoder Band

The LFO's support traditional waveforms like Sine, Triangle, Square, Saw. But the LFO's also support  Step and Glide with up to 32 Steps. SynthMaster will even let you modify/round the shape of the steps! Glide is similar to Step but does not snap directly to the step but instead glides up or down. The LFO's can be synced or free running.

The 2D Envelopes generate two outputs which is useful for mixing Vector oscillator levels.

With two independent synth layers it is obvious to use a keyboard split and have e.g. pad or strings in lower part and a lead in upper part. Unfortunately SynthMaster do have a traditional keyboard split function. However, you can use a Keyscaler modulator to implement keyboard splits. In general the KeyScalers can modify parameters depending on which part of the keyboard you are playing so you can use it for more than just a simple keyboard split.

The Easy Parameters consist of eight knobs and two XY pads. These parameters can be used to control the most important parts of the synth engine e.g. filter sweep and can also be modified using the scaled down SynthMaster Player. This way all the knobs and buttons of the synth engine can be hidden away for the live player, who can just focus of the Easy Parameters instead.

Each modulation target can have up to 4 modulation sources. The modulation matrix has 64 modulation slots, which can be filtered to get a better overview of the settings for a specific source or target. You can assign modulation by right-clicking a control and hope to find the right source or target in the deep popup menu - or you can assign it directly in the modulation matrix. SynthMaster 2.8 introduced drag-and-drop modulation where you simply drag a modulation source onto a modulation target. This makes it much more intuitive to set up modulation. If you are used to working with Native Instruments Massive, you will recognize and appreciate this workflow.


The arpeggiator has several modes: Up, Down, UpDown, DownUp, UpDown2, DownUp2, AsPlayed, Sequence, Chord, Arpeggiate.The arpeggiator has 32 steps. You can define Velocity, Note Number, Note Length, Slide and Hold parameters for each step.You can import your own MIDI patterns into the arpeggiator. You can simply drag one of your MIDI files and drop it on the arpeggiator view - nice and easy! The arpeggiator can import both monophonic and polyphonic MIDI patterns. SettingsOther FeaturesSynthMaster support Multidimensional Polyphonic Expression (MPE) which allow advanced MIDI keyboard controllers like ROLI Seaboard to generate MIDI events for each key pressed on different MIDI channels and thereby control modwheel, pitch bend etc. individually for each note.SynthMaster has 8 knobs and 2 XY pads available as "Easy Parameters" that can be assigned as modulation sources and used to hide away the complexity of the synth engine and just let the live player edit these easy parameters. Of course the Easy Parameters can also be connected to your MIDI controller.



  • Very high sound quality
  • A sound designers dream with endless possibilities and a huge sonic range
  • Very flexible modulation architecture
  • Drag-and-drop modulation
  • Flexible Arpeggiator/Step sequencer with drag-and-drop MIDI import capability
  • Continuously updated with new improvements


  • The UI has a lot of tabs which makes it difficult to get an overview and there is a lot of tab switching going on.
  • It can be difficult to get an overview of all the modulations - here Massive is much more intuitive.
  • Would have liked a keyboard split function for the two synth layers.

This is the Swiss army knife of synths... One synth to rule them all...  Highly recommended! When it comes to sound quality and versatility this is really is a 5-star synth though. However, due to the UI issues I can only give it 4,5 stars.


These prices are the MSRP. However KV331 Audio often has special offers e.g. seasonal discounts or discounts to all who subscribe to the newsletter. 

MSRP for SynthMaster is only $99 - that is a bargain for a synthesizer as powerful and flexible as this!

You may also consider the Standard bundle for $129 with 150 expansion presets or the Everything bundle for $279 with all 1800 expansion presets.

If you are a sound designer SynthMaster is a must-have. If you are only interested in using the presets and want to save some money you can check out SynthMaster Player instead. This is a lite version with limited editing capabilities - only the Easy Parameters may be modified. It comes with 1100 factory presets. MSRP for SynthMaster Player. There is also a SynthMaster Free Player which is free but only contains 350 factory presets.

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