Review – Thorn by DS Audio Software

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There’s a new synth in town and it will capture your imagination with its spectral synthesis prowess, power and ease of use – but it’s not your garden-variety virtual instrument.


by Rob Mitchell, Jan. 2018


If you haven’t heard of Thorn yet, the new synth plugin by DS Audio Software, then maybe you’ve heard of Diversion or their effect plugin Tantra. Both Diversion and Tantra are top-notch music software plugins, so it’s no wonder when a new synth plugin named Thorn was announced, many people took notice and the word spread quickly. So what is Thorn exactly? It is a three oscillator synth plugin that isn’t your garden variety VA synth. It uses spectral synthesis, along with PWM, RM (ring modulation) and FM, and hard sync is available too. Dual multi-mode filters, multistage envelopes, LFOs, several effects and its Glitch Sequencer gets the audio shaped up in no time.

The system requirements are a modern CPU with SSE3 support, Windows Vista (or higher) or OS X 10.9.x (or higher). Thorn is available in VST, VST3 and AAX formats (32-bit and 64-bit). The install is very easy and a display appears to select whichever format(s) you’d like. It uses a serial number for authorization.

After you start Thorn in your host, you will see its user interface which has the advantage of being basically all on one screen. You don’t have to switch between many tabs to get where you want. The other parts of the synth where you do have to click on a button to get another view are for the Glitch Sequencer, arpeggiator, effects and modulation matrix. Nearly everything else is on one display at the same time.


The Oscillators

Thorn includes three oscillators with standard tuning controls including octave, semitone, and cents. They also have panning and volume controls. The Phase control of each oscillator let you choose from three settings: Gate (resets each voice when it starts), Random (random setting for the phase when a voice starts) or Free (free running). The unison has up to 8 voices with detune and stereo spread controls. Each oscillator also has its own sub-oscillator that is one octave below the main oscillator’s pitch. The sub-osc has three different waveforms to choose from; the first is a square wave while the other two are variations on a pulse waveform. The oscillators can be output to either (or both) of the two filters.

If you want to get that vintage virtual analog sound, the oscillators have those types of waveforms available: sawtooth, sine, square and triangle. You can also select from many spectrum tables in the dropdown menus. Thorn uses sixteen frames of spectrum tables, and you are able to smoothly morph between them using the POS control. Clicking on the display of the waveform will open up the Harmonic Editor. There are 128 harmonics in sixteen tables that are at the bottom of the display. Drawing in the upper part of the display changes the amplitude and phase for the selected table. Drawing tools are located in the lower-right that allow you draw in a free-form manner, or you can adjust the odd or even harmonics. The last choice will add organ-like harmonics. A right-click on the display will bring up a new menu will several more choices for editing the frames. Some of the choices include copying/pasting frame contents, boosting the higher or lower harmonics, randomization of phase and amplitude, and importing of a WAV file.

The OscFX menu for each of the three oscillators has several types of spectral effects (Phaser, Wah, Comb, and others) which let you manipulate the sound and venture into new territories. This is also the same menu where you can select from other modulation choices such as FM, RM, PWM and Sync. FM and RM use another oscillator for the modulation to work, but the Sync function uses an internal oscillator.

Besides the three oscillators, there is an additional noise oscillator. It includes many short samples you can use as the attack part of the preset you’re designing. You can also use it as a regular noise generator to add another layer to your sound. The included samples can repeat endlessly by enabling the Loop button, and there is key tracking available as well. Other controls include pitch, offset (start position), panning and volume. You can also direct its output to either (or both) of the two filters.


Filters, Envelopes and LFOs

To the right of the noise oscillator is the Harmonic Filter. It allows you to edit a spectrum curve that’s made up of 8,192 harmonics. In a way, it can be thought of as large-scale EQ for the oscillators. It is very similar to the oscillator’s editor in the way you edit, and has the same drawing tools in the lower-right. It has a large number of presets ready to go, but of course you can design your own. The Shape control will adjust the shape/curve inside the display to the left or right, and the Balance control changes the low or high frequencies. There is a menu where you can select from many functions used for editing the spectrum tables. Some of these functions include smoothing or sharpening the blend between the harmonics, maximizing the amplitude, shifting the entire spectrum up or down by one harmonic, randomize phase, boost highs or lows, and much more. These commands can be easily repeated (if needed) by using the left/right arrows in the upper-right. This makes it easy to re-apply the same function you just chose and you won’t have to use the command menu over and over.

Thorn also has two analog-modeled filters with several modes available: Clean (24 dB per octave slope), Dirty (12 dB per octave slope), and Fat (12 dB or 24 dB per octave slope) low pass, high pass and band pass, Crisp and Subtle low pass (recommended for pads), Bandpass (48 dB per octave slope) and Hypercomb types rounding out the bunch. Several of those I mentioned are of the zero delay feedback type. A drive control is included to increase the signal pre-filter. Standard cutoff and resonance controls are here, and there are key and velocity tracking settings you can adjust. The two filters can run in serial or parallel modes. I won’t go into all the differences in sound between the filter types that I noticed, but suffice it to say there should be plenty here to keep you happily tweaking and designing your presets.

There are three analog-modeled envelopes (ADSR) included in Thorn. Each of the envelopes has its own key and velocity tracking settings. AMP ENV is for the amplitude, ENV1 is normally assigned to the cutoff for the two filters, and ENV2 can be used for nearly anything you’d like. Alternatively, you can use ENV1 on one filter and ENV2 on the other. Using the modulation matrix (more on the matrix later) you can assign any of the envelopes to nearly anything you want. They’ve also given Thorn two multi-stage envelopes. They each have their own rate control and can be synced to the host. These MSEGs can be set to either a curve or step mode. The Curve setting uses nodes to build slopes and/or curved shapes, and the Step setting uses block-shaped steps. The step’s width and height can be adjusted, and can use up to sixteen steps. The Shuffle control will add an amount of swing to the pattern, and the Gate setting will change the length of all steps at once. The MSEGs can also be set to Loop mode or One-shot.

Two LFOs are available in Thorn, and there is an additional Vibrato function. There are three main controls for each LFO: Speed, Shape and Phase. They can be synced to the host, and there are several shapes to choose for the LFOs. There is a fade-in amount and there are three operating modes: Poly (per-voice), Mono (same for all voices) and Mono Sync (similar to Mono, but the LFO phase follows the host). Amount Control lets you choose what will affect the LFO amount. The Vibrato has nearly the same controls as the LFOs, but they’re slightly different: Rate, Fade In, Velocity Scale and a menu for the Amount Control selection.


Glitch Sequencer and Apreggiator

Thorn includes a sixteen-step Glitch Sequencer that allows you to add several effects in a step-based format. As each step of a sequence rolls along, a couple of the ways it can affect Thorn’s sound is to have an increase or decrease in the filtering amount or a sputtering/repeating sound to it. You can select from a Repeater, Low and High pass filters, Bit crusher, Sample rate reduction and a Gate. Setting the amount for each effect is accomplished by changing its level in each cell of a sequence. Each effect is enabled with a button along the left side, and several presets are included. They’ve also added a randomize button on the right side for each effect. Additional controls include a speed control, step amount (up to sixteen steps), sync (to a key press or envelope), mix level, and these can be set to occur before or after the main Effects section. The sequencer works well and sounds great when used with certain types of presets. I like the randomize feature, but I thought it could use a Randomize All button as well. Clicking on each of the six buttons is bit much if you want all of them randomized, whereas a single click would be much more efficient.


The Arpeggiator lets you set up a one to sixteen note pattern. The notes are selected by setting each step to the number value you’d like to use. A slider bar adjusts the velocity amount for each step, and the gate amount can be adjusted per step as well. Octave, Tie and Shuffle/Swing controls are also here, and there are seven play modes (Up, Down, Up/Down, Random, etc.) from which to choose. There is also an overall Gate control to dial in the setting you’d like for all steps. Once you have it set the way you want, you can easily save your arp settings. One thing I’d like to see added is a way to set all step values back to the default value again. For instance, a click on the Gate label could put all the steps gate levels to the same value at once. You can reset everything all at once from the preset menu, just not one of the settings (such as Gate) at a time. MIDI import would also be a welcome feature.


Effects and Modulation Matrix

There are many effects in Thorn. All the standard ones are covered here, including Distortion (six different modes), Lo-Fi (a bit crusher), Chorus, Phaser (with four different modes), Flanger, Delay, Reverb, EQ and Compression. They can be sorted in the order you’d like with a simple drag-and-drop. All of these sound good and get the job done nicely. Each of the effects have at least four or five presets you can select from (the reverb has 21 presets) and you can save your own. You might already know this from reading some of my previous reviews, but one of my favorite features in a synth these days is the ability for the effects to be set up as target for modulation. Thorn excels at this, as basically every effect parameter is available as a target in the modulation matrix.

The Modulation Matrix has a standard configuration with columns for Sources, Controllers, Depth/Amount and Targets. The sources include several areas of Thorn; Envelopes, LFOs, MSEGS, Mod and Pitch wheel, Vibrato, Sustain, Velocity, Gate, Random, etc. The targets include nearly every single part of Thorn, and this is where a good amount of its strength lies. As I mentioned earlier, besides the effects, you can choose from such items as Oscillator and Filter controls, Envelope stages, LFO controls, MSEG settings, each of the sixteen steps in the Arpeggiator and Glitch sequencers, and more. Controllers can be the typical suspects such as modulation wheel, aftertouch or velocity, but they can also be anything else that the Source list has in it. Thorn also provides drag-and-drop modulation for quick and easy modulation assignments.


Wrapping Up

Wavetable synths seem to be all the rage these days, but Thorn takes a different route and that’s what makes it special. It is one to be reckoned with, and stands up on its own merits with a unique sound. Since it is still in the earlier stages of development, I expect that the few small issues I ran into will be ironed out in no time. I asked the developer if microtuning might be added at some point, and the answer was “Yes”, so you may see Scala file support soon.

The spectral synthesis, filters and Glitch sequencer can yield so many combinations of sounds that you really have to check Thorn out it for yourself. The layout is just about perfect, it’s easy to understand, the price is right and, more importantly, it just sounds great. Since it’s still a new synth plugin, there is room to grow and a few new features will probably be added along the way. Thorn was introduced with an intro price of $69 USD and went to its standard price of $119 USD after December 31st. You can get more info and a demo version here:




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