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Synth (Analogue / Subtractive) Plugin by Smart Electronix
Free (Donationware)
ASynth by Smart Electronix is a Virtual Instrument Audio Plugin for Windows. It functions as a VST Plugin.
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Overall: 2007   1947

30-Day: 1973; 7-Day: 1438; Yesterday: 3484

by Antti of Smart Electronix

ASynth is a six voice virtual analog synthesizer featuring two oscillators and three circuit modelled filters.


  • 6 Voice polyphony.
  • 2x/4x/8x selectable oversampling.
  • MIDI CC automation.
  • Two oscillators:
    • Osc 1 with sawtooth and square waveforms.
    • Osc 2 with sawtooth and pulse waveforms.
  • Three circuit modelled filters:
    • MS20: 12 dB/oct lowpass filter with signal level dependent resonance.
    • Mini: 24 dB/oct lowpass filter from the 60's.
    • XPander: Multimode 24 dB/oct filter with 16 different responses.
  • Two ADSR envelopes (VCF and VCA).
  • One LFO with 6 waveforms.

Latest User Reviews

Average user rating of 4.00 from 5 reviews

Reviewed By The Chase
December 29th, 2015

This is one of the first/oldest VSTs that blew my socks off with its sound quality. I don't have as much use for it now, but it still sounds as good as anything out there and would be perfectly adequate for a bread-and-butter subtractive synthesizer. Antti never got enough credit for this.

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Reviewed By mhemnarch
January 28th, 2008

Straightforward, pleasant, and very useable. Much like the rest of the synth.

This thing is a vintage-analog beast! At its core is a multimode filter that not only covers the usual options - bandpass, allpass, bandreject, hipass, lopass, most with several different amounts of poles allowed - but also can be toggled between Minimoog, Xpander, and MS-20 imitations. The versatility this gives the synth can't be overestimated. It can go from crushing, dark resonant basses to pristine keyboards to outrageous self-oscillation (which is actually outrageously usable, more than any other freeware synth that I've tried).

This thing has two oscs, a filter, and an LFO. I'd give it a lower rating for being so barebones, but the filter - what a filter! - elevates it at least to an 8. I've seen plenty of much more complicated synths that can't produce nearly such a range of sweet sounds.

Lots of vintage analog-y sounds, as you'd expect. All of them sound great, and they do a great job of showing off the synth's capabilities, though the synth begs to be manually tweaked.

I've never had any trouble with this synth crashing and don't expect to any time in the future. Solidly programmed.
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Reviewed By bongodrums
February 19th, 2006

Up until I found ASynth, I was using MiniMogue as my source of moog sounds. Well, this thing has better (cleaner, bitier) filters and I prefer it's interface. It has 3 filter models (based on three different synths), and they do sound different. All the usual moog sounds are here; they just sound really nice, especially when linked with delay. My only gripe is that the filter envelope doesn't seem to be able to handle full sweeps from a fully closed to a fully open state :( No matter what you do, you can always open the filter up more manually, which is a bit sucky, as the filter is so very nice on this one.
The GUI is clean, if a bit simple, but it does allow you to quickly do what you want in an unobtrusive manner. Like others, I find the filter button a bit hard to determine what option is selected, but other than that there are no other UI issues. It has portamento mode, which is great for those classic note slides, and a good bottom end.
Overall, one of the best free vsts out there, IMO the best free moog softsynth. Lovely.
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Reviewed By abi
November 13th, 2005

this synth sounds great. it´s my number one synth for fat synth basses, though i always plug some compressor plug into its strip to fatten it up a little more. i also like to sample a sound with some filter mod involved and use it in a sampler. the oscillators and filters sound really nice to my ears. i especially like the oberheim filter models, which have a unique character that i haven´t come across in any other synth or fx plugin. the gui could be tweaked a little bit ( as mentioned in the first review, it´s rather difficult to see whether a switch is turned on or off). featurewise, i would like to have another lfo, more options for the oscillators like sync and so on. i like the fact that it doesn´t provide any fx, cause in most cases i prefer dedicated plugins over internal synth fx anyway. what i really would like to see though would be a plugin using the filter models provided by asynth, combined with some lfo/env-modulation options. this would be really nice. well, i urge everyone in search for fat analog sounding basses to try this one out!
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Reviewed By pummel
January 28th, 2005

Summary: This is one of the best sounding synths around. Even without
effects, it sounds great. And, its CPU load is less than most. It is a
bit lite on options, but that is easily overlooked.

The interface is cleanly designed; however, it takes a while to get used
to the rocker switches. It is not obvious at first which position is 'on'
and which is 'off'. Small nit, though.

This is what it is all about. I cannot say that ive heard a synth that
can better Asynths raw sound. (And since there are no onboard effects,
that is all you get).

Here, the synth falls a bit short of its potential. This year, what
moves me is sound quality and 'elegant simplicity'. Features, in
and of themselves, are beginning to annoy -- especially when it gets
to multiple redundant copies of modules and the like. But simplicity
does have its limits. Asynth only has the one LFO as a modulation
source. In this case, I wish for more: any of ring modulation,
hard sync, FM, pitch would be nice additions.

The included docs are fine. Really, there is not much to document.

The included presets are excellent. Especially, the first 32 or so.
In spite of the lean control set, there is a surprizing variety to
the sound pallet.

Antti provides a contact email; but to be honest, Ive had no need to
use it.

Excellent. It is donationware; so we determine this ourselves through our donation choice.

Rock solid on my hosts/CPUs
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