Any synth will do it - just set the oscillators down an octave or 2. Sub basses are usually better when they are kept simple - try sine waves with a saw and low cutoff to add a bit of character.

You really just want to use the sub to add some "oomph" to tracks - the character from basses comes in the mid range

Predator has a really nice sub bass preset. Called Sub: Lowy bass

i use it all the time

traingle & sine wave are most common but square can be used as well (the opposite odd harmonic from a triangle). i actually use trilogy for all my sub's as they are full and instantly usable.

I find Predator particularly useful for sub-bass. Two oscillators used, one sine, one saw run, through the LPF. Didn't require much EQ'ing, just pulled out freqs' below 40 then a bit of compression. Job done.

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Rob Papen's SubBoomBass has an excellent implementation of sub-bass. The synth was essentially modeled on his existing Predator synth, but was customized for bass sounds in terms of features, oscillator waveforms, etc.

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Since you asked for V-Station, pull up the preset "Bass 8," then lower the Amp Release, bring the Filter Resonance up to just about half, and bring the Filter Cutoff down nearly all they way(play with it until it suits your track).

Makes for a decent Sub-bass patch.

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the free VST Crystal does some of the best Sub Bass, but you'll have to EQ out some of the unwanted low end, since it does some monsterous lows.

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Absynth's "Massive Dark Bass" and Trilogy's "Deeeeeeeeep" or something are usually my first choices.