dfan says

Well, that’s what I’m calling them, anyway, although it’s kind of fruitless to try to pin down the style of even one record here. This is the last group that Zappa called the Mothers (and the last group that he named after anything other than himself) and it shows; you get the feeling this is a real group of musicians creating music together and not just a bunch of session players. It’s a lot of fans’ favorite lineup and so far (I’ve actually listened through 1981) I agree.

With Over-Nite Sensation (1973), Zappa discarded the big-band jazz style of his previous two records and made pretty much straight-ahead rock music. The “pretty much” hides the fact that even in the most straightforward tunes here there is often some surprising stuff going on in the background or the breaks. When I first heard it I was a bit disappointed that it wasn’t more out there but it’s grown on me a lot (you will hear this sentence again in the future).

Apostrophe (‘) (1974) is a bit more interesting, with more of the prog tendencies that I named this period after. These two albums were his biggest sellers to date, and I like them fine; a few more wrinkles would be nice, but they are really well done.

The wrinkles come out in full force with Roxy & Elsewhere (1974), a double live album with lots of overdubs (a format Zappa used a lot). Even the regular rock tunes have a bunch of twists, and there are some really interesting instrumentals; side 2, which is mostly sophisticated instrumentals, is my favorite side of his since the second side of Absolutely Free. It manages to be superbly virtuosic while still being sweaty and down-to-earth, not bloodless at all. There are a few missteps (a swollen overweight remake of “Trouble Every Day” from Freak Out typifies everything I dislike about how music progressed from the 60s to the 70s) but there’s an amazing amount of good stuff here.

One Size Fits All (1975) just about rounds out this period. It’s lots of people’s favorite Zappa album, and I can understand that. There’s a great mix of rock, funk, and prog, capped off with two versions of a winkingly pompous anthem. I certainly wouldn’t mind if he had managed to make a few more albums in this vein.

Bongo Fury (1975) was made with Captain Beefheart and is pretty much the last gasp of this ensemble. I love Beefheart, and the first track, “Debra Kadabra”, really got my hopes up for some gonzo greatness, but in general it feels like Zappa and Beefheart compromised on some common ground rather than going all-out weird. In my opinion they both made better records on their own.

Some of the musicians in this group (Napoleon Murphy Brock, George Duke, Ruth Underwood, Bruce and Tom Fowler, Chester Thompson) made guest appearances later (and given Zappa’s penchant for using old material for new albums, more music from this period would show up), but his next album was made almost solo, and after that he picked up a new bunch of musicians and the overall style changed again…