Review – Synthmaster One from KV331 Audio

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Synthmaster One is a new wavetable synth from KV331 Audio – it’s certainly worth a look if you’re a fan of KV331, and if you’re not a fan, you may become one.


by David Baer, May 2017


Big Picture

In this review we’ll take a close-up look at Synthmaster One from KV331 Audio.  Regular readers of SoundBytes Magazine will know that I’m an enthusiastic fan of KV331’s flagship synth, Synthmaster (which is now at version 2.8), not only for its many competencies but also for its reasonable price and resultant excellent value.  KV331 has unequivocally stated that there is a Synthmaster 3 in the pipeline, estimated to be released in 2018.  So, where does Synthmaster One fit into this story?

Synthmaster One is, on the one hand, a scaled down version of Synthmaster.  On the other hand, it does something that Synthmaster only does in a somewhat limited fashion: wavetable sound production.  In this context, “wavetable” means there is an array of single-cycle waveforms available to an oscillator.  These may be traversed with seamless morphing between adjacent entries, and the traversal of the table can be controlled manually or modulated with an LFO, envelope or other modulation source.  Synthmaster supports a wavetable size of sixteen.  Synthmaster One allows unlimited entries in theory; in practice it’s probably wise to try to limit the number to no more than 128.  But even with an upper bound of 128 entries, this opens up some expanded possibilities in sound design compared to Synthmaster’s table size upper limit of sixteen.

Let’s nail down one point before going any further: Synthmaster One is not to be confused with Synthmaster 1, which was the predecessor to Synthmaster 2.  Are we all clear on that now?   🙂 

At present, Synthmaster One does not offer an integrated wavetable editor.   The factory wavetables included are said to have been produced with KV331’s in-house wavetable editor, a feature that KV331 has promised will be included in Synthmaster 3.  So, an obvious question is: do the paths of Synthmaster One and Synthmaster 2.8 converge in Synthmaster 3?  The answer is that they will, somewhat.  Synthmaster 3 is intended to be able to load Synthmaster One presets, so there will be an upgrade path for current Synthmaster One users.  However, Synthmaster One will remain a separate instrument with a planned upgrade path that includes a multitimbral (four-voice) capability.  KV331 Audio has an even more ambitious plan for it: a hardware version.

Before we go any further, though, let’s get some basics out of the way.  Synthmaster One is available as 32-bit and 64-bit for PC and Mac.  Formats are VST, AU and AAX (AAX Mac-only).  A standalone version is also supplied on both PC and Mac.  An iOS version is said to be forthcoming, but we will disregard that one in this review.  List price is $79 USD, but KV331 always seems to have some kind of sale going on, so check the web site (URL at end of article).  A very attractive cross grade price of $29 USD is available for owners of Synthmaster, discounted to $23 as of the date of this writing.  Also, another attractively-priced option is a bundle of Synthmaster and Synthmaster One for $99 USD (this is the current sale price; again, check web site for up-to-date pricing).  Those who have purchased the Synthmaster Everything Bundle can get Synthmaster One for free.


Synthmaster One Architecture

Synthmaster One implements a clean and straightforward overall design that those already familiar with Synthmaster will require little effort to learn.  But even those new to KV331 should not face a substantial learning curve.  Most of the signal flow can be understood intuitively from the organization and presentation of the UI.  But a few things will require a read through the manual.  Hopefully I can illuminate those murky areas as we go.

Synthmaster One supplies two identical oscillator units which feed two filters that can be configured in several ways (more on this shortly).  The oscillators are the most complex aspect of the instrument.  Everything that comes later in the signal chain is fairly standard fare.  We have two identical filters offering a nice variety of analog models.  We have two LFOs, two general-purpose envelope modulators that augment two dedicated amp envelopes and a dedicated vibrato module.  Finally, we have an FX section with a serviceable collection of effect unit types from which to choose.

All in all, this is a far easier instrument to understand than Synthmaster.  Upon first encounter, the first thing that is immediately obvious is that it looks nothing like Synthmaster.  When it comes to UIs, we are definitely in “eye of the beholder” territory.  Some will no doubt find objection to the Synthmaster One UI, but for me it’s much superior to the UI of Synthmaster, which has light lines and letters on dark background and too-small windows.  For me, the new look is a significant improvement.


The Oscillators

The most interesting aspect to the Synthmaster One story is the oscillator units.  By “oscillator unit”, I mean a module consisting of two actual oscillators that can interact in several ways.  The resultant sound produced by the two oscillators can be duplicated producing up to sixteen total voices for a unison sound.

The first of these oscillators can load a single-cycle waveform or a wavetable.  A wave-shaper algorithm can be applied (in both single-cycle and wavetable mode).  A small (too small for practical use in my opinion) image of the current waveform is shown graphically.  We have no way of knowing from this image whether we currently have a single-cycle waveform or wavetable loaded.  The clue as to which is the case is the label on the leftmost knob below the “Algorithm” label.  If it is “Index”, we are in wavetable mode.  Otherwise the knob is labelled “Tone”, meaning we are in single-cycle waveform mode.

The second oscillator can just load a single-cycle waveform (however, any waveform that the first oscillator can load is available).  The subpanel that presents the second oscillator is labelled “Sub” (for “sub-oscillator”), but there are actually five ways in which it can be employed.  In addition to being a second oscillator whose output is added to that of the first, it can alternatively take on several possible modulator roles: it can be used to frequency or phase-modulate the first oscillator, it can modulate the amplitude of the first oscillator, and finally, it can do ring modulation with the first oscillator.  Since it has a semitone adjustment range of +/-48, in sub-oscillator mode it can be used to add higher-frequency content as readily as supplying a conventional sub-oscillator augmentation.

Synthmaster One ships with a splendid collection of both single-cycle waveforms (many from classic analog synth sources) and an extensive collection of files containing wavetables.  KV331 did a first rate job on this part of the product.  Wavetables compatible with the Serum wavetable synth may also be loaded, and there seems to be an abundance of these freely available on the web.

But back to the oscillators themselves – the controls for pitch, pan, various unison parameters, portamento, etc. are nothing unusual, so we’ll not spend any time on them here.  Likewise, vibrato (lower corner of the UI) offers no mysteries.  Off screen (i.e., not visible when the keyboard sub-tab is shown at the bottom) are two controls that can be used to add analog-like drift to the oscillator pitches.  The manual designates the oscillators as “stereo”.  However, they will only play back mono wave data.  The “stereo” comes from the ability to pan and/or to spread unison voices across the left-right panorama.

There are two aspects of the oscillator units that are non-obvious.  The first is that of importing one’s own waveforms and wavetables.  Users may import their own files, either single-cycle waveforms or wavetables.  For wavetables, the length of each entry in the table must be 2048 samples.  Since Serum has an identical requirement, Serum wavetable files are candidates for importation.

File names for both single-cycle and wavetable data may include a root note designation and multiple versions of both types can be imported.  When played, the oscillator interpolates between the nearest lower and higher waveforms or wavetable entries based upon MIDI note number – a very powerful feature especially when it comes to wavetables.

The second non-obvious aspect is the wave-shaper processing.  Wave shaping is available for both single-cycle waveforms and wavetables.  We could devote an entire article to this feature, but we’ll have to summarize and suggest the interested reader explore further in the manual.  The wave shaper offers algorithms of five types: spectral (basically, this is filtering), bend (stretching a waveform in one place and compacting it in another), sync (similar to sync-slaved oscillators in classic subtractive synthesis), pulse-width modification (another stretch/compact type of alteration), and bit reduction.  The operation is done on the waveform (a single-cycle waveform or the current waveform from the wavetable if we’re in that mode).

Before we go any further, let’s dispense with an explanation of the Index/Tone control.  In wavetable mode, the Index control dictates the position in the wavetable – simple enough.  In single-cycle mode, however, the control is called Tone and its function depends upon the wave-shaper algorithm currently selected.  For most algorithms, the Tone control is used to specify the cutoff frequency of a high-cut filter.  For the spectral algorithms (ones that are actually filtering functions like high-pass or low-shelf), it always specifies a frequency, but might be other than the cutoff frequency of the high-cut (low-pass) filter.

We get just one wave-shaper parameter control in wave-table mode, the Tone control being preempted by Index, which has nothing to do with the wave-shaper.  But we get the Phase control in both modes.  OK – time for more explanation.  Phase only actually affects signal phase for two of the seventeen wave-shaper options.  What phase controls is properly explained in the manual, and it’s usually the thing you’d most expect it to affect.  For example, the sync algorithms turn the current waveform into a shorter repeated version of the original waveform.  In this case the Phase control dictates the frequency of the slaved (synced) oscillator.

All this leads to wanting to mention two enhancements that are highest on my Synthmaster One wish list.  One would be for an expanded display of the waveform that could show what the effect of the wave-shaper is (and do so in far greater detail than the tiny waveform image above).  The second is for labels on the Phase control that actually say what is really being controlled, even if it was something vague.  For bend or sync algorithms, “Amount” might not be very specific, but it’s better than “Phase” which is downright misleading.


The Filters

We could easily go on at some length about the oscillators, but it’s time to move on, and the next logical subject is the filters.  There are two identical filters which according to the documentation are of the zero-delay-feedback variety.  So what’s up with that?  Analog filters are inherently zero-delay; digital filters are not.  Getting the most analog-like mojo from a digitally modelled version of an analog filter is regarded as one of the key problems to solve by savvy synth designers.  This gets into some very hairy territory very quickly – unless you design digital sound processing devices, you’re probably better off not worrying about the gory details.  At the end of the day, the proof of the pudding is in the eating.  Synthmaster One filters sound great.  That’s really all that matters.

The available filter types are:

  • Ladder – modelled on the Moog, with low-pass, high-pass, band-pass and band-reject, each with both 12-dB/octave and 24-dB/octave slopes.
  • Diode Ladder – modelled on the filter in the Roland TB-303, with just one option, low-pass 24-dB/octave.
  • State Variable – modelled on the state variable filter found on the Oberheim SEM, with low-pass, high-pass, band-pass and band-reject, all 12-dB/octave.
  • Bite – modelled on the filter in the Korg MS-20, with low-pass 12-dB/octave and high-pass 6-dB/octave.

This all makes for quite a wonderful collection of useful and characterful filters.  The Acid key adds behavior such that resonance is lowered as cutoff frequency is lowered.  The Boost key restores some volume due to its reduction when higher levels of resonance are set.  The other controls are familiar filter fare.

The configuration of oscillators and filters is set in the panel shown to the right.  We have three choices:

Split Mode – oscillator unit 1 outputs to filter 1 which outputs to amp envelope 1, oscillator unit 2 outputs to filter 2 which outputs to amp envelope 2.

Parallel Mode – outputs of the oscillator units are combined and sent to filter 1 and filter 2 which are running in parallel independently of one another; filter 1 then outputs to amp envelope 1 and filter 2 to amp envelope 2.

Series Mode – Like parallel, except that filter 1 outputs to filter 2 which outputs to amp envelope 1 (amp envelope 2 can be used for other modulation in this case without affecting oscillator/filter sound production).

The routing picture also reflects the sub-oscillator mode of each oscillator unit.  In the above example, oscillator unit 1 uses the second oscillator as a sub-oscillator (first and second oscillator outputs are mixed), and oscillator unit 2 has the second oscillator (the “sub” oscillator) modulating the amplitude of the first oscillator.


FX, Modulation, and the Rest

In the routing subpanel seen in the previous section, you can also see the FX section.  We have six slots into which effects may be inserted.  The FX section processes the output of both amp envelopes (or just amp envelope 1 in Series mode).  The available effects are Distortion, LoFi, Ensemble, Phaser, EQ, Vocodor (yes, Vocodor, but more on this momentarily), Delay, Chorus, Tremolo, Reverb and Compressor.  The effects may be inserted in any order.

All the on-board FX types are straightforward enough that we won’t devote any more time to them here, except for Vocodor.  When using the Vocodor effect, Synthmaster One needs to be loaded into a DAW project as an effect with MIDI input (how this is done will depend upon which DAW you are using – easier in some than in others).


The two LFOs and four envelopes (two general purpose envelopes and two amp envelopes) are once again quite straightforward, and we need not spend any time in discussion.  One thing is worth noting, though, and that’s that the LFOs have access to every single-cycle waveform that the oscillators can use.  That means not only that there is a huge and very diverse collection on hand, but that imported waveforms are also a possibility.

The modulation matrix is found as a tab of the area occupied by the keyboard in the full screen image above.  A single slot, one of twelve in total, is seen to the right.  Each slot has one originating source, one “via” source and two destinations.  The more commonly used modulations, like LFO, can be directly assigned outside the mod matrix by dragging and dropping (e.g., dragging the LFO1 label and dropping it on Cutoff in Filter 1).  Assignments made this way will be also seen in the mod matrix. 

Assignments in the mod matrix must be explicitly made for everything else.  The usual sources you would expect are available: direct MIDI control (e.g., mod wheel movement), indirect MIDI data (MIDI note number from a note-on event), and random values generated per note-on.  The “via” source is simply a secondary control governing the amount of the main source that is “let through”.  The main source might be an LFO.  If the “via” source is the mod wheel, then the mod wheel can be used to control the depth of the LFO affect in real time.

There’s more, of course.  I haven’t discussed the nifty arp/sequencer at all, to which the manual devotes about eight of its (currently) 49 pages.  But one more thing merits mention: the factory content.  It’s good in many ways.  As stated earlier, there are a wealth of single-cycle waveforms included in the factory content as well as a healthy selection of wavetable files.  The frosting on this cake is the hundreds of presets created by A-list sound designers (with more presets to come, if I’m not mistaken).  Top all this off with an excellent browser to make finding what you’re looking for a breeze, and it’s all good.


Is Synthmaster One for You?

Synthmaster One has a number of demo videos made by its creator, Bulent Biyikoglu, which can be found at the KV331 web page (URL below).  Plus you will find some fine demo tracks that ably show the range and fine sound quality of this instrument.  To my ears, this is a marvelous-sounding synth that comes loaded with great presets.  But if rolling your own sounds is your thing, Synthmaster One is about as easily programmed as anything I’ve seen of comparable sophistication, and programming it is substantially easier than programming Synthmaster.  Part of the reason for that is because there are not as many component parts, of course, but I quite believe part of it is due to a well-considered design that resulted from the experience gained with Synthmaster over the years.

KV331 is known for offering considerable value for the prices being asked, and Synthmaster One seems to keep with that tradition.  The cross-grade available to owners of Synthmaster is a total no-brainer to my way of thinking.  Other options, straight-up purchase or bundle with Synthmaster are good deals as well, especially since KV331 always seems to have some kind of sale happening.

Synthmaster One is a real winner and an instrument I can heartily recommend.  It gives me a very positive feeling about what we can expect in Synthmaster 3, to which I look forward with considerable anticipation.

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