Originally posted by chris mood
[B]In popular music is very common to outline the 4 chord during a "bridge" section. Technically you are not modulating because you are still within the diatonic key,

Whether it modulates is depending on the song, so it could be either yes or no. On written music this modulation is not noted because key signature of a song is indicated by the last chord not each modulation that occurs. Music would be a mess, because some music can move through many and I mean many key signatures. Modulation causes contrast in music which is a must in a good masterful composition. Music, like a painting is not one color but many colors.

and at this point the 4 chord is clearly not functioning as an extension of the 1 or 5. To dismiss it seems frivolous, you would be denying everything the Blues stands for.

No chord within a chordal structure of a key is an extension of another chord. Not even the I chord and the others which revolve around that chord. Griphon does hold water when saying the IV chord can be functional as a suspension. Especially in a C.P. such as I - IV - V7 and the minor version i - iv6 - i(6th extension on iv chord is optional). Although limiting to that function is a musical opinion probably based on musical experience, because the IV can play as many roles as any other chord. Just like many other chords can serve as a suspension, bVII, iio, bII, viio, V7, and Io. Some work for some musical styles while others don’t.

As for a 1 to 4 progression I can name at least 2 dozen songs off the top of my head that utilize this function (Feeling Allright, Can't Always Get What You Want, etc..). I think the 4 chord definitely has its own unique aural character, In fact I think its one of the easiest and most distinguishable chords to hear within the diatonic system. Why you would want to invent some theory that disguises the relevance of the sub-dominate is beyond my comprehension.

The I-IV progression could stand alone as just a I chord continued, but the IV chord keeps the progression moving. The next chord after the IV chord could actually be anything and will relatively have the same effect if it was moving from the I chord. I think you would understand this griphon, because this is your primary use of the IV chord. Try this chord progression so you can hear the contrast in modulation that occurs from using the IV chord.


CM:I V ii IV
FM: I vi ii V I
e:-0----1----0----0----0----1----0----0--|
b:-0----0----1---------1-----------------|
g:------0---------2---------3----3----2--|
d:-----------0----3----0-----------------|
a:-3-----------------------------3-------|
e:--------------------------3---------1--|


This progression goes from C major to F major.

have fun chris.