consider the word 'growl'. its an onomapoetic noun. consider how you move your mouth and your tounge in your mouth when you say the word. the clue for how to make this sound is the 'o' and the 'w' in succession, the 'g', 'r' and 'l' are fine tuning and harmonic details which you can get in later. so do it, say 'ow', make your voice real low and say it slow, like in the tunes.
a synth is a good place to start but not strictly necessary as long as you have a sampler. they are a good combination. synth1 is a nice synth and free and all
Start with a saw wave on a synth. Create layers with different frequencies. Use distortion, filters and compression if required.
Thnx for the comments i played around with the massive plugin from native instruments I think I got a nice bass out of that one could you check out the track and tell me what you think? http://www.myspace.com/nyctophobia1988 Trackname is "The Ruler Is Back" Thnx ^^
As said detune and distort, put a tight envelope on it as well. I find syncing the oscillators gives a more nasty sound Also slap a lowpass on it and attach an envelope to open up the cutoff so the growl jumps out of the sound so to speak
Rickenbackers have more growl than Fenders, and the scale is a little shorter. check this: play drums