yo
Reece is a generic name for that sound, some call it hoover, some call it reece, some even call it bass ! so don't get confused with its names. If you go on DnB forum, you'll find that people are always making challenges to get the best "Reece" sound. it is like talking about the Virus TI here
That sound can be found in the form of samples in many DnB oriented sample CDs, i don't know their names but I know it exists.
And of course, you can create it from scratch on a synth like the Virus or any analog/Va synth. I read somewhere that TeeBee creates its reece sounds on a Supernova II, some people use the JunoX VST (which later became Hydra).
To give you a flag, i'd say that on a scale of 1->10, the reece sound would be around 6/7 if you know well your synth. The sound itself is not that hard to get, but its modulations and further process (including correct compression) makes it sound nice and pupming.
As far as the automation goes, you can innovate! try what ever you want to modulate yours, but as far as i know, all reece sounds have their cutoff modulated by amodwheel or envelop, not sure tho!
There is a forum called "Dogz on Acid" which deals a lot with dnb and all its related stuff and sounds. You can check it out and be sure to learn a lot about dnb prod there!
hope this helps !!!
