I can't speak for what dubstep IS because it seems I'm always being told that "real" dubstep sounds different than what I would think. Whatever, I don't know, it seems to me to revolve around bass heavy music with a particular BPM and dark style to the beat, though there are artistic variations of course. Though I don't really listen to dubstep, I am a huge dub fan and I can tell you that there are some key elements in dubstep that were taken from roots dub, people like Augustus Pablo (one of my all time favs), King Tubby and Scientist etc. etc. Electronic music is one of my favorite fascinations with music these days and the differences can be extremely subtle or similar in certain cases but most genres do indeed rely on genre specific techniques, though some genres are defined by the absence of said techniques.
In dubstep, the elements that are taken from dub seem to me to be the foundation. One of these elements is the groove, which is similar in dubstep to dub, however in dubstep, it usually revolves around a double time BPM where dub is usually half of that. The reason, from my understanding, that dubstep uses double time is to accentuate the quick hi hat sequences and allow breathing room to rock a high LFO rate in the wobbles. Also, you have the snare hitting on the 3 in dubstep, because of this double time, where in dub it typically would hit on the 2 and 4, though there a few different classic drum patterns that are used in dub, IE: a one drop would be different than a rockers beat. I find that most dubstep I have heard, and I don't really listen to dubstep on my own time usually, is more sparse in track production. Even the more complex tunes are not anything near as complex as say a psytrance track or a psydub track.
Old school dub is also not as layered as any modern psy tracks and a lot of roots dub revolves around LIVE mixing where much of music today, if not the vast majority of it is mixed through software and automations. There is no clear cut "right" way to do it but they have distinctly different sounds. Live mixing preserves every little nuance, where automated mixing can be extremely precise and perfect. Different styles for different vibes I guess. Overall, what defines "dubstep" for me is bass heavy electronic music, focused at or nearly 140 BPM with a emphasis on the kick and snare being on at least 1 and 3. The wobble bass seems to me to be huge in this genre though I don't think it is necessary to make a track defined as "dubstep." I think any heavy low end takes care of that. As for "dub," I would consider anything that is a remix of reggae with spare vocals, lots of delay and possibly live mixing to be at least dub influenced. Dub is a super wide genre, it spans past reggae but it usually centered around reggae. For me, the defining elements of dub are lots of tape delay, lots of reverb and a spacey liquid vibe with little to no vocals. King Tubby said dub is "Like a volcano in yuh head!" and I could definitely see that.
Just my point of view but it's interesting topic to think about. What draws you to certain music and what compels you to define it certain way are definitely things worth thinking about when analyzing your view on the world around you.
edit: Wow I never addressed IDM. IDM stands for intelligent dance music and is a pretty wide open term. It has been used for all different kinds of electronic music, usually music that sounds more sophisticated. It is also often associated with the type of music that artists like Aphex Twin and Squarepusher make but that could border on breakcore as well. Though Aphex Twin has stated that he would prefer to call his music "brain dance." When I think of IDM, I think of sophisticated electronic music, something fresh and maybe pretty complex. It's a very general genre term and usually something labeled as IDM would be further categorized down. For example you could call Aphex Twin IDM then get more specific with each track, some are more breakcore, some are ambient, some are just fucking weird. Anyway, IDM is pretty openly used and like somebody said earlier in this thread, it seems to not be used as much anymore.
This post was edited by HERETICtheory on Mar 6 2012 01:16pm