Access Music User Forum

It is not THAT different from other distortion-over-filter sounds. The thing that is striking about it, is that the pattern that it is playing is almost random - it could be assembled from different samples out of a longer tweaking session. Your approach should be trying to reimagine the sound before the distortion, for example when the pattern starts: "Ah-ah-ah-ah-ah-ooh-wah!". An "ah" sound means that the filter cutoff (and resonance) is in a "middle position", while an "ooh" sound means the cutoff is on a lower frequency. While the note itself that is played goes up an octave (I think). A nice way to do this can be to map a soft knob to a MIDI CC, and in the modulation matrix make this CC control oscillator pitch and filter cutoff in opposite ways.

It might take a while...

A good acid line is a combination of 3 elements.

1. A good acid sound.
2. A good cutoff tweak pattern.
3. Changing to gate or arp note length time and automate it.

You get a gate effect by controlling the volume. For example, a simple gate effect of a short burst on every beat, can be achieved by using a square wave shape LFO in mono and clock mode (LFO-s for all notes are together fully sync'ed to MIDI), rate set to 1/4, routed to control patch volume (or just oscillator volume if that is enough for you).
For more complex gating patterns, you can change the rate ratio, and even select one of the wavetable waveforms for the LFO. Change the contour position and the initial phase until you are satisfied.
But what if you want full control over the gating pattern, and don't want to use any of the ready made elements that come with the Virus? One option is the arpeggiator, in user pattern, and ">matrix" mode. In the arpeggio editing area, put a tall bar where you want the sound to be loud and a flat bar where you want silence. Then go to the modulation matrix, select the arpeggiator value as the source and whatever volume you want to gate as the destination. I don't like this option because the arpeggio always starts with the note you press, meaning that if you play at least some of your notes staccato and not on the first beat of the bar, the arpeggio pattern will shift accordingly. Here is a feature request from Access: Please add an option to sync the arpeggiator just like a mono LFO, so that the pattern always starts on the first beat of the bar, regardless of when I play the note.
The other way of having full control over the gating is a little more complicated since it involves side chaining. First you need to manually create an audio clip of the gating pattern you want, by using any sound, even plain noise. Then loop it and route it into the Virus input (and out of the main mix). On the patch you are creating, turn on the envelope follower in the effects section, and it will make sure the patch sounds off in sync with the input.

Regarding the sound from the song you linked to, I still don't have the free time to recreate it but @lonis, it is not the usual TB303 sound. It's a filter+resonance->distortion sound that is a little random and unpredictable in relation with the notes played and the filter cutoff frequency.