Review – ArcSyn by SPC Plugins

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Do you need a creative/useful synth plugin with a great sound? ArcSyn from SPC Plugins just may be the synth for you.


by Rob Mitchell, Mar. 2017


SPC Plugins are the makers of some high quality music software plugins. A few of those include Gater-Pro (a stereo trance gate), Freek (a stereo frequency shifter) and Wobbulator (a ring modulator). All of the plugins have modest prices and a low CPU usage. ArcSyn is their latest product. I have heard many good things about it, so I thought I should check it out for this issue of SoundBytes.

OK, so what is ArcSyn? It is a virtual analog subtractive synthesizer plugin with over 450 presets. All of its waveforms are generated internally. No single-cycle waveforms or wavetables here – this is straight-ahead synthesis. Wave-sequencing can be used in the LFOs, and there are many types of waveform shapes to choose from. The oscillators and filters are 4-times oversampled and yield an excellent sound.

For PC users, you’ll need Windows XP (or higher) with an SSE2-capable CPU, and a VST 2.4 compatible DAW/sequencer host application. For Mac users, you’ll need an Intel Mac running OS X 10.6 (Snow Leopard or higher) and a host application. ArcSyn is available in 32/64bit VST and AU formats.

After purchasing ArcSyn, the buyer receives an automated email with their name and serial code. Using this info, they unlock the demo version of ArcSyn and it becomes the full version. You don’t have to be connected to the internet when loading ArcSyn, it just checks for the saved serial code. Mac and PC versions use the same code, so you can run both if you want. 

Once you have it unlocked, you can check out all of its features and listen to some of the many included presets. You can see nearly everything on its main screen, so you won’t have to switch between tabbed displays. It has its three oscillators towards the left side, two filters in the middle, modulation matrix in the upper-right, with the effects and envelopes on the right side. At the bottom left is the LFO section. There is more to it than that, but I just wanted to give you a general overview of where things were located. Now we will look at it in more detail.


The Oscillators

Three oscillators are included in ArcSyn, and there are many waveforms to choose from. In fact, there are 71 of them available. As I mentioned earlier, these aren’t samples; they are all generated from scratch. Some of these waveforms are not the usual types you’d find in most other synth plugins on the market.  Of course, the usual suspects are here for that classic sound: Saw, Pulse, Sine, and Triangle. It also has Super Saw, Super Square, and Super Triangle. Each of those “Super” types use eight waveforms that can be detuned to give it a huge/lush sound. Many of the others are interesting additions which I happen to really like. Some of those are the Quad Xor, 1-Bit Noise, FM and Harmonic Sweep. There are 12 different types of noise available. I won’t go into much detail on all of these as the manual already has in-depth descriptions.

Each oscillator has a Shape and Level control. Shape will adjust different qualities of the sound depending on which waveform you select. If you choose the “SuperSaw”, it adjusts the detune amount of the eight waveforms. If you select the “Saw Chords”, the Shape control will cycle through 32 choices of 4-voice chords using either a saw or square waveform. You want a C7sus4 or C diminished? No problem. It shows “C” as the base note for every chord, but it is actually just relative to whatever note you are playing. In other words, the intervals are worked out for you. The “Level” control is simply the level of output for the selected oscillator. The usual Octave and Semitone tuning controls are available, and they’ve also included EXP and LIN detune controls. EXP (exponential) will cause a gradual increase in speed for the beat rate you hear as you play higher notes on the keyboard, and LIN (linear) has a constant rate across the entire keyboard. Phase Reset is also available. It causes the phase to go zero each time a note is played, which can be desirable for certain types of presets. Last but not least, there is a mix level slider to adjust the output to either (or both) of the two filters.



The two filters can be configured in Series or Parallel using the Routing button. Each filter has 37 filter types, including choices of 1, 2, 3 and 4-pole Low pass, 1, 2, 3 and 4-pole High pass types. Others include two Band pass types, four different Notch types, five SVF (State Variable Filter) types, 4, 8, 12 and 16-pole Phaser types, and there are many others. Below the filter cutoff control is a button which links the two cutoff controls when it is enabled.

Besides the standard cutoff and resonance controls, there are eight different types of Drive available. This gives you several types of distortion to choose from, such as Soft and Hard Clip, Quantize, Tube, etc.  The ENV1 and NOTE are controls to adjust the amount of the envelope’s influence over the cutoff and for the key tracking.  Other controls include panning, a mix control for the balance of the two filters, and the output level. On top of all these nice features, they can self-oscillate as well. They mention on their website that they were modeled after the filters in the Oberheim Matrix 12. I can’t say if they are zero-delay filters or not, but I don’t care too much about that since they sound great anyway.



The LFO section of ArcSyn is complex (which I like!), and you can put together some interesting settings with it. There are eight separate LFOs, and each of them has a standard rate control which can be synced to the host if you like. The rate can be cranked up to a speedy 100 Hz when needed. The LFOs can also be used with up to sixteen varied waveforms in a sequence. The Offset for each step/shape can be adjusted, and Delay will fade-in the effect of the waveform on the audio. If you’ve set it up with more than just one sequence step, you can select from different modes for the way it will play through the steps you’ve configured. These choices include Forward, Reverse, Forward/Reverse, Random, Random Forward/Reverse, and Single-Shot.

Below each of the slots for the shapes is a slider control to change whichever waveform you’ve selected. If you select Pulse for instance, it will change the width. If you select the Tri/Ramp, it adjusts the shape from a triangle to more of an up-ramp, or down-ramp, or anywhere in-between. When using the Slope/Step shape, the slider will adjust it between two to sixteen steps. Anyway, you get the idea. Below that slide control are the Wave (adjusts semitone) and Step Level amounts. With or without a waveform in each slot, the Wave Level amount adjusts the LFO output in a semitone amount (0-127). Here’s what happens.  If you leave all the slots empty (no waveforms loaded in any of them) and just make adjustments to each Wave Level setting and assign the LFO to the Oscillator pitch in the modulation matrix, you will hear it play back a melody of some sort. If you load up waveforms into the slots, it will do the same thing, but the pitch follows whatever shape is loaded for each step.

One very handy feature is the button to the right of each label, such as the one next to the numerals above the waveforms. For example, say you setup a sequence with sixteen steps. It will be a blank slate, except for the first step which has the default waveform in it (Sine), or maybe you changed it to something else. If you click the button to the right of the number “1” above the shape, it will copy that waveform shape across all of the steps for you. It works in the same manner for the Wave and Step level settings. What a time saver! Now imagine all those settings I mentioned above, but multiplied by eight LFOs – very powerful to say the least.  All of these can be connected to other parts of the synth using the modulation matrix.


Envelopes, Modulation Matrix, and Effects

ArcSyn has four AHDSR (attack/hold/decay/sustain/release) envelopes. The first envelope is tied to the cutoff for the two filters, and the fourth envelope is for the amplitude. There are adjustable slope settings for the ADR stages of the envelopes. The slider’s center position is a linear setting, and it works in an exponential manner if you move the slider to the left or right. Even though the first and fourth envelopes are hard-wired for the filters and amplitude, any of the four envelopes can be used as sources for additional modulation targets.

The Modulation Matrix allows up to sixteen slots for modulation. Each of these can have up to two sources, and these can be combined in many different ways using the Modifiers. Some of these include Smooth, Quantize, Curve, Divide, Difference, and there are many others. Some of them are musical, as the two sources can be combined and then quantized to various music scales, such as major, minor, harmonic minor, etc. The manual explains the details on how each of these operate, so I won’t take time going over them. They all work well, but I’d like to see a few more destinations added. It would great to have the addition of the separate envelope stages, and it would be useful to be able to modulate the effects.

ArcSyn has three effects available per preset, and you can put them in whichever order that you want. These cover nearly everything you’d like (32 in all), including chorus, EQ, flangers, delays, autopan, limiting, phasers, and a reverb.  The reverb could be improved a bit (maybe some type of modulation?), but it gets the job done.

Here is a short explanation about the effect routing: If you choose the Series setting, the first effect gets its feed from the effect busses in stereo. The first effect then goes to effect two, and then on to the third effect. If you use Parallel mode however, the left signal goes to effect one, and the right signal goes to effect three. Effect two will then get the combination of the signals from effects one and three.

A couple of small items I wanted to mention before I close this out are the Init and Random functions. In some synth plugins, I have to figure out where an Init preset is hidden away so I can start my own. Sometimes they don’t even have one to use, and you must create one yourself. Not so with ArcSyn, as there is an easily accessible INIT button in the lower part of the screen. To the right of that button is the RND (Randomize) button. Getting a little short on your own creativity, or just want to try your luck? Hit the RND button, and a new preset is generated. The cool thing about it is that it uses the preset you’ve loaded in to make the new preset. It works best if you start out with a more complex preset.



I appreciate having the Supersaw choices for the oscillators within ArcSyn (and all the other types), but I’d still like to see unison added. While I’m making requests, if they end up adding unison, maybe they could add a stereo spread control for it too.  Also, a “Favorite” function for the presets in the browser would be nice.

Besides my few small quibbles, this synth is really a joy to use. With so many useful and varied waveforms, and an awesome LFO section tacked on, it might just become your new preset-designing workhorse. If you just love synthesis in general, you really should check out the demo and give it a try. There are so many possibilities available for sound design that you will probably get hooked (like I did) in no time.

ArcSyn retails for $89 USD, and there is a demo version you can download from their website here:




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