Richard,
What I was reading back then, was some generic electronics instruction series that I couldn't recall who published it even if I wanted to. I think it was originally published in the mid to late 60s. I know it was in the early 70s when I was getting into this. If you recall, at that point in time speakers weren't nearly as powerful as they are today. Back then, if you had 25 watt Celestions, you had the cream of the crop! But that manual was referring in general terms for speaker enclosures for HiFi applications, and if I remember correctly, that was about building studio monitors.
I did build a cab with 4x12" Celestion 25 watt speakers out of plywood and lots of coats of paint and wax to seal it. It was a monster. I remember it made my dad laugh out loud sometimes watching my scrawny teenage ass trying to move that thing around. I think it weighed more than I did. If it didn't at first, it certainly did after I experimented with it later on.
The cab was roughly the same size as the Fender Dual Showman Reverb TFL5000 cab, but it was 3" deeper so I could have a 12 cubic foot enclosure. The speakers were not placed on top of each other or side by side, but rather they were staggered from top to bottom. The top was mounted on the left side of the cab, and the next one down was mounted on the right side, and I repeated that with the bottom half of the cab too. I did this to find out if the cab would sound better with all four speakers resonating in a large enclosure like that, but left my self the option of putting baffles in between each speaker, which I did after a few months. After that, I decided it could sound better if I added a reflex baffle, and opened a port for each speaker. So, I added a couple of 90 degree baffles in each cab, and opened a 6" hole on the opposite side of each speaker. If you haven't visualized it at this point, that cab I was hauling around was essentially four 1x12" cabs in a single big box. All that added wood by this time made this thing so heavy, it was ridiculous, I had to put casters on it. I did like the sound of this thing by this time, but it was not the easiest thing to take to a gig. Small clubs and going upstairs was out of the question, but large auditoriums and outdoor gigs it was great.
The amp I was using was a home built thing that wasn't a copy of a Fender of Marshall amp. In fact I don't know what kind of circuit it was. It came from a book titled Electronic Diagrams. and it was an 80 watt guitar amp design. The parts were all sourced from various electronics parts stores that were all over the place at the time, I remember the transformers were made by Philips, and the tubes were RCAs. All that stuff was dirt cheap back then.
The whole point of me doing that was to build a bigger, and better amp than the Vox 2x12 combo I had at the time. After about two years of experimenting with it, I came to realize that the Vox could still keep up with that amp and sounded a little bit better. So I ended up selling that rig, and started getting into Fender amps for something different. I never looked back after that.