Synapse Audio’s Antidote Synthesizer Reviewed


Synapse Audio’s Antidote was one of the first Rack Extension synths to make it to the PropShop and, despite being one of the most expensive, remains one of the most frequently recommended REs in Propellerhead’s own forum. What’s all the fuss about?

Architecture Overview

Antidote is a pre-patched subtractive synthesizer with, by contemporary standards, a fairly rudimentary architecture. So rudimentary, even, that it lacks several of Subtractor’s key features. Unlike most well-thought-of synthesizers, Antidote’s reputation is earned not by doing many things but by doing a few things, very, very well.

Antidote’s audio path is as follows: oscillators > multi-mode filter > EQ > distortion > phaser > chorus > delay > reverb > compression. Modulation is on the flexible side for a pre-patch synthesizer. Two reasonably featured LFOs and a mod envelope can be routed to most parameters and a five-row mod matrix adds performance controls and external CV.

For bonus points, Antidote includes an arpeggiator that I prefer to RPG-8 and the effects chain accepts external audio.

Oscillator Banks

One of Antidote’s defining features is that it doesn’t just have oscillators, it has oscillator banks. Two stereo (!) multi-oscillators with modifiable waveforms can be stacked up to twelve high, each, not including dyads, which can be 3, 4, 5, 7, 12, 19, or 24 semitones above the set pitch. The modifiable waveforms cover most of the analog bases, mostly making up for the lack of cross modulation. e.g, The Analog Saw waveform’s modifier is a hidden oscillator which performs oscillator sync.

Adding some variety are an oscillator called Ringwave, actually a pair of ring modulated oscillators, and ten wavetables. In what I can only describe as a stunning achievement in the field of overkill, Antidote also has not one but two sub oscillators, one sawtooth and one square wave. The levels of the two banks and two sub oscillators are controlled via individual faders. A fifth fader in the mixer controls pitch drift.

Icing on top of the icing on top of the oscillator cake, the oscillator banks can be free-running or be set to a specific phase relationship (or have one be free running and the other be resetting, because why the hell not?).


Much like the oscillator section, Antidote seeks to do much with its one filter, giving it eight modes: one, two, three, and four-pole low pass; two-pole band and high pass; diode ladder low pass; and Sallen-Key low pass. Though having just one filter can be a bit limiting, the many modes and CV modulation options do much to make up for that.


Two LFOs are provided. In free-running mode, they are global; key synced, they are per-voice. You have the standard analog waveforms to choose from, with one modulation target each (though this can be augmented using the matrix), and the option of tempo sync. In tempo synced mode, cycles can be as long as six measures or as short as a 64th note triplet, with many musically useful values between; when unsynced, rates ranged from .01hz to 100hz.


As is standard for this age, three ADSR envelopes are available. Times range from zero to ten seconds for the attack stages, zero to twenty seconds for the decay stages. and – interestingly – two milliseconds to twenty seconds for the release stages (the portamento time also uses two milliseconds as the minimum). I did not test this but, according to the manual, the amp and mod envelopes have a linear attack stage and the filter envelope, a logarithmic attack stage.

Mod Matrix

Five rows of modulations are possible in Antidote’s Mod Matrix. The only columns are source, amount (bipolar), and destination.  LFOs can additionally be scaled by the mod wheel and aftertouch to a limited degree. Helpfully, sources include constant and random values and the list of destinations, is comprehensive. (Interestingly, it includes LFO2’s phase.)


The arp has twenty patterns, the same range of synced rates as the LFOs, up to four octaves, all of the usual modes, and variable gate length. I like it.


As stated above, Antidote includes: EQ (with bass enhancement), distortion, phaser, chorus, delay, reverb, and compression, in that order. The effects are based on other Synapse products and better featured than most on-board synthesizer effects (not to mention, most synthesizers don’t have so many). For example, the delay includes three modes, modulation, and separate L/R times. It’s worth mentioning again that you can use the effects with external audio but keep in mind, the effect order is fixed.

It’s worth noting that the phaser’s LFO can only be tempo synced and that the chorus’s cannot be tempo synced.

Synapse Antidote Rack Extension - Back Panel


Four CV inputs for use via the mod matrix; dedicated sequencer, mod wheel, pitch wheel, and amp ins. Dedicated outs for the arpeggiator and each LFO and envelope.


The best description for Antidote’s sound is probably big and warm. I think of it as my Prophet, because is has a similar “oomph” to it. In my opinion, this is a synth for people who think Subtractor or Thor lack weight. Though its architecture can be limiting, Antidote makes up for it by including many high-quality sound shaping tools that complement each other greatly.

The oscillator banks alone can create many interesting timbres, from fat to piercing to atmospheric to sterile to organic. Though cross-modulation would be nice, I don’t blame Synapse for not including it; cross modulation would have made the synth CPU hungry and Antidote does just fine without it. My one complaint about this section is that the wavetables, though adding breadth to Antidote’s capabilities, are not as varied as they should be. For example, Fat Saw sounds quite similar to the default waveform,  Analog Saw.

The filter’s generic modes are transparent and I like them for most sounds. When more character is needed, the diode ladder gives grit and the (gain-compensated) Sallen-Key gives punch. I do find having just one filter a little limiting but this is one hell of a filter to have just one of.

The effects section is much more generously featured than I’d ever expect from a synth. All of the effects are very high quality. Though none have become favorites of mine, the only complaint I have is that the reverb is incapable of decay times less than one second. It’s a quite good long decay reverb but for the relatively subtle ambiance that a synthesizer can best benefit from, the built-in reverb comes up… paradoxically short.

(But fear not of forever being lost without a reverb. I brought this up on the Synapse forum and Richard acknowledged this as a deficit and indicated that he was considering including more algorithms in an update. Also, there are, you know… standalone reverbs.)

Ease of Use

Antidote was designed to be accessible to synthesizer noobs and is successful in making the main functions of a subtractive synthesizer relatively easy to use. However, for some more advanced bits of programming, you have to work harder than you would on certain other synths. Occasionally, you’ll have to trick Antidote into doing what you want. For instance, if the filter is fully tracking the keyboard and you need the cutoff sweep to start below the fundamental (I’m thinking of the Blade Runner Lead), you have to sacrifice a mod matrix row, negatively applying a constant to the filter.

There are other little things that bother me, as well. The envelope stage times are bottom weighted and the filter cutoff tool tip shows values from zero to one hundred percent, which don’t find useful (also, a disappointing resolution). Worse, key controls (pitch bend range and velocity trims) were placed on the back panel, as a space saving measure.


Antidote brings a new and distinct voice to the Reason rack but lacks Thor’s depth and Subtractor’s balance of simplicity and versatility (granted, I’m more fond of Subtractor than most). If you are looking to add variety to your rack without leaving the virtual analog/subtractive realm – especially if you think Reason’s native synths aren’t as beefy sounding as they could be – Antidote is the first RE I would think to recommend. However, the limitations of pre-patched synths must be kept in mind, especially for those of us who have been spoilt by Thor. If you never touch Thor’s mod matrix, this is not an issue, but for some, the decision of whether Antidote’s glorious oscillator banks and multi-mode filter are worth the trouble could be difficult.

Preset users should just go ahead and buy it. The patches that come with the synth are very nice and there are a good number of free and commercial refills available.

Example Patches

The patches below highlight a few observations I’ve made.

Blade Runner Lead: Tricking Antidote into behavior normal for other synths.

Analog Style Trumpet: Antidote sounds fat, even set to a solo brass sound.

Synth Marimba: The oscillators’ modifiers and subtractive synthesis, hand in hand.
Excellent sound, limited flexibility, high price.

For reference, I would give Thor 4.9 stars and Subtractor, 4.8.

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colcifer is a multi-instrumentalist with a weakness for harmonies and waltzes. You are likely to find him trolling the Propellerhead forums, pretending to be a synthesizer expert.