Theory for dummy (me)

I've got lots of questions...I'll begin with this:

Notes in First riff = E, F#, G, A, A#

Notes in Fourth riff = E, F, G, G#

With the diminished scale in mind, is it okay for a song to begin with E dim and end up in B dim?...Should the song stay in the same key signature?...Do the notes within a certain scale determine the key of an enitre song???

AND/OR--If these progressions/notes were played slowly...say, the first note was held for four beats--could you do something like a bass fill in E minor during the duration of that one particular note????

Please help. I'm very confused......

You don't actually need any theory here. You should experiment with what you have been writing, and see if it sounds good. If it doesn't, you'll need to change stuff.

Now a diminished scale can be (in whole and half steps) WHWHWH etc.... (the whole half diminished)

or HWHWHW etc.... (the half whole diminished)

Now if your first riff is E F# G A A# Then I guess your going for the Whole half diminished

For the second riff you've got E F G G#, that's E half-whole diminished (keep in mind that every note in a diminished scale could be the root, although the form might change). If you are going for B diminished whole half, this is the correct scale.

Now it is perfectly legal to have both of these scales in your song for your riffs, although I would make some kind of transition line, maybe with chromatic notes.

Yes you could make the bass fill in E minor, but again I would make some sort of transition, say a guitar or bass letting out the b5 right at the end of the measure.

Thanks. That makes sense to me. I've been playing for years but never learned to read, learned my fretboard properly, etc. I guess my question is more general, about the application of theory in writing an entire song. Should songs be composed entirely in one key signature? This is probably a matter of style and opinion. I want to play a more melodic style of metal...With that in mind, should a song that begins in E min remain there throughout? Or should you just play what sounds good and have theory dictate what can be played over any given part? Any input would be appreciated...

Songs can change keys. Songs change keys all the time. A cool one to do is Em to Bm, or Em to G major since you're in Em already. Experiment, there's plenty you can do with metal, it doesn't have to be all in one key. Either way is fine, but key changes can be more interesting. Look at Franz Ferdinand. I know he's not metal, but his transitions and key changes are some of the best I've ever heard.

Also, you can use theory to dictate your songs. I think it's not a great idea because you can't possibly know everything about music theory. However, if it sounds good, there is a 100% chance that music theory covers it somewhere. So just play what sounds good, because technically you ARE using music theory.

No, songs don't have to stick to one tonal center (key signature). Play what sounds good but listen to see if each part progresses naturally to the next part. Changing keys without a plan or structure can make a song sound like several different songs shoved into one. A good tool is to keep an aspect of the previous key when you change keys. Such as a common rhythm or dynamic. This tactic links the two contrasting parts into one chain.

Yeah you could use a bass fill in the first riff over E. The fourth riff however will probably sound more like F minor. E can be used as a harmony for V in F minor, and then F the tonic. Classical views on modulation say that when a change of key is done, it should be done at a cadence or have a cadence immediately following to firmly change the tonal center of the music.

This seems right because the first riff right of the bat is in E minor, the last note A# (or as I'll put it Bb) is the 7th in a C7 chord. A C7 chord in E minor (bVI7) is a common harmony, but more advanced in it's understanding. Blues and some rock music uses it quite often. Back to where I was going. Since it's going to F minor in the fourth riff. Bb and E (first note in the fourth riff) both are in the the C7 chord. The next note that follows is F, the tonic note of the new key. Your cadence and a secure key change. However this depends on what you are actually playing, so use your own judgement.

There's also theories that don't stick with classical views of key signatures, such as chromatic harmony and atonal music. I say play what sounds good and you won't go wrong.

And then later on you can get into tritonal substitution, and have a grand ol' time with key changes in one song!